Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 50 of 262 results
  • Collective dynamics of Bulk Metallic Glasses Studied by Molecular Dynamics Simulations  Open access

     Vallés Sales, Araceli
    Department of Applied Physics, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    El desenvolupament de nous materials té un gran impacte en totes les àrees de l¿enginyeria, i en particular a l'enginyeria aeronàutica. Els vidres metàl·lics son materials relativament nous, amb excel·lents propietats mecàniques; el seu estudi és imprescindible per la seva implantació tecnològica.Les propietats mecàniques macroscòpics d'un material estan determinades per la seva estructura atòmica. En particular, la fractura de materials fràgils s'inicia per la generació de modes de vibració. Als vidres metàl·lics, d'estructura amorfa, l'espectre vibracional té característiques específiques.En aquest treball s'estudien les propietats vibracionals dels vidres metàl·lics emprant simulacions de dinàmica Molecular. L'estudi es centra en sistemes binaris simulats emprant potencials atòmics de Lennard-Jones (LJ), Morse i Embedded Atom method (EAM), de tipus semiempíric. Com als vidres metàl¿lics basats en Pd, el quocient de les masses d'ambdues espècies en les simulacions és alt, essent 2 en potencials LJ i 1.67 en potencials Morse i EAM. Simulacions a gran escala permeten simular sistemes amb heterogeneities a escala nm, i la simulació a velocitats de refredament diferents permet obtenir configuracions en diferents estats de relaxació.La dinàmica de les vibracions atòmiques dels vidres metàl·lics és un tema de debat. L'origen de l'excés dels modes de vibració conegut com Boson Peak (BP) no és clar. Als sistemes analitzats s'observa que la dependència de la posició i la intensitat del BP amb la mida del sistema és feble. Al contrari, la intensitat de la BP augmenta amb la velocitat de refredament, mentre que la seva posició es desplaça a freqüències menors. Els resultats obtinguts emprant potencials de realista tipus EAM coincideixen amb les dades experimentals disponibles en vidres de composicions similars.El factor d'estructura dinàmica, S (q, ¿) es calculà també en sistemes grans per obtenir informació sobre el comportament de les excitacions acústiques en vectors d'ona baixos. També es va obtenir la relació de dispersió de fonons longitudinals i transversals.En tots els casos estudiats, l'amplada del pic, GL,T(q), augmenta amb la freqüència. S¿observa una regió lineal a baixos nombres d'ona i una flexió quan s'aproxima el límit de la pseudo-zona de Brillouin. Aquest comportament és el mateix que l'observat experimentalment emprant Inelàstic X-Ray scattering (IXS).La velocitat del so macroscòpica s'obté quan el nombre d'ona tendeix a zero. Els valors obtinguts amb potencials EAM i Morse estan d'acord amb els valors mesurats experimentalment en sistemes de composició similar.El límit Ioffe-Regel (IR) es defineix com la freqüència a la que la longitud de coherència del fonó és similar a la longitud d'ona de fonó. S'observa que la freqüència IR augmenta lleugerament als sistemes més relaxats. El límit IR longitudinal és troba en tots els casos a freqüències superiors a la freqüència del BP. Contràriament als resultats obtinguts en els sistemes LJ, el límit longitudinal IR en Cu20Pd80 y Cu50Pd50 és molt a prop de la posició del BP, mentre que el límit transversal IR és molt per sota d¿aquest valor; aquests resultats estan d'acord amb els obtinguts experimentalment per IXS. S'infereix que el potencial EAM augmenta la interacció entre modes longitudinals i l'excés de modes del BP.Finalment s'obtingué la fragilitat en els sistemes estudiats mitjançant el càlcul de la viscositat a temperatures diferents. És conegut experimentalment que la fragilitat augmenta amb la velocitat de refredament. Els sistemes LJ mostraren una fragilitat molt més alta que els Morse i EAM. No obstant això, fins i tot els sistemes simulats amb potencials realistes van mostrar valors de la fragilitat molt superiors als obtinguts experimentalment a causa de l¿extrema velocitat extrema de refredament de les simulacions.

    The development of new materials impacts on all branches of engineering and, in particular, in aerospace engineering. Metallic glasses (MG) are relatively newcomers to the world of materials science and have excellent mechanical properties; its study is mandatory to allow its technological implantation. The macroscopic mechanical properties of a material are linked to its atomic structure. In particular, the fracture behaviour of brittle materials is initiated by the generation of vibrational modes. In metallic glasses, with amorphous structure, the vibrational spectrum has specific features. In this work, the vibrational properties of metallic glasses are examined by Molecular Dynamics simulations. The study was focused in binary systems, which were simulated using different interatomic potentials: Lennard-Jones (LJ), Morse and the semiempirical Embedded atom (EAM). As in Pd-based metallic glasses, the ratio of masses of both species was high, namely 2 in Lennard-Jones potentials and 1.67 in Morse and EAM potentials. The large scale simulations allowed us to simulate systems with nm-scale heterogeneities frozen-in during the quenching process. Different relaxation states were obtained by changing the quenching rates of the simulated MGs. The collective vibrational atomic dynamics of metallic glasses is a longstanding subject of debate. The origin of the excess of vibrational modes known as Boson Peak (BP) is not clear. In the systems analysed the dependence of the BP position and intensity on the system size is found to be weak. On the contrary, the BP intensity increases with the quenching rate, while its position shifts slightly to smaller frequencies. The results obtained by using realistic, semiempirical EAM potentials compare well with the experimental data available in glasses of similar compositions. The dynamic structure factor, S(q, ¿) is also computed in large systems to get information on the behaviour of acoustic excitations at low wavenumbers. The dominant frequencies O L,T (q) are determined for each considered wavevector, in order to compute the relation of dispersion of longitudinal and transverse phonons. In all studied cases the width of the peak, GL,T(q), increases as the frequency increases. A linear region at low wavenumbers and a bending when approaching the limit of the first pseudo-Brillouin zone are found. This behaviour is the same than that observed experimentally by Inelastic X-Ray scattering. The macroscopic sound speed is obtained for wavenumbers tending to zero. The values obtained with EAM and Morse potentials are in qualitative agreement with those obtained experimentally in systems of similar composition. The Ioffer-Regel limit (IR), where the coherence length of the phonon is similar to the phonon wavelenght, was computed. It is found that the Ioffe-Regel frequency decreases slightly when applying faster quenching rates. The longitudinal Ioffe-Regel limit was found at frequencies higher than the Boson peak frequency for all the cases, although the diference in EAM systems is much reduced. Contrary to the typical results obtained in the LJ systems, using EAM potentials in both Cu20Pd80 and Cu50Pd50 the longitudinal IR limit is very close to the position of the BP while the transversal IR limit is found well below. This behaviour is coherent with that found by IXS measurements. It is inferred that the EAM potential increases the interaction between the longitudinal modes and the BP excess states. Finally the fragility of the studied systems was obtained by calculating the viscosity at different temperatures. Lennard-Jones systems showed a much larger fragility than EAM and Morse systems. However, even systems simulated with more realistic potentials showed fragility values much higher than those obtained experimentally. This is attributed to the extremely high quenching rates used in simulations, as it is known experimentally that fragility increases with the quenching rate.

    El desenvolupament de nous materials té un gran impacte en totes les àrees de l'enginyeria, i en particular a l'enginyeria aeronàutica. Els vidres metàl·lics son materials relativament nous, amb excel·lents propietats mecàniques; el seu estudi és imprescindible per la seva implantació tecnològica. Les propietats mecàniques macroscòpics d'un material estan determinades per la seva estructura atòmica. En particular, la fractura de materials fràgils s'inicia per la generació de modes de vibració. Als vidres metàl·lics, d'estructura amorfa, l'espectre vibracional té característiques específiques. En aquest treball s'estudien les propietats vibracionals dels vidres metàl·lics emprant simulacions de dinàmica Molecular. L'estudi es centra en sistemes binaris simulats emprant potencials atòmics de Lennard-Jones (LJ), Morse i Embedded Atom method (EAM), de tipus semiempíric. Com als vidres metàl.lics basats en Pd, el quocient de les masses d'ambdues espècies en les simulacions és alt, essent 2 en potencials LJ i 1.67 en potencials Morse i EAM. Simulacions a gran escala permeten simular sistemes amb heterogeneities a escala nm, i la simulació a velocitats de refredament diferents permet obtenir configuracions en diferents estats de relaxació. La dinàmica de les vibracions atòmiques dels vidres metàl·lics és un tema de debat. L'origen de l'excés dels modes de vibració conegut com Boson Peak (BP) no és clar. Als sistemes analitzats s'observa que la dependència de la posició i la intensitat del BP amb la mida del sistema és feble. Al contrari, la intensitat de la BP augmenta amb la velocitat de refredament, mentre que la seva posició es desplaça a freqüències menors. Els resultats obtinguts emprant potencials de realista tipus EAM coincideixen amb les dades experimentals disponibles en vidres de composicions similars. El factor d'estructura dinàmica, S (q, ¿) es calculà també en sistemes grans per obtenir informació sobre el comportament de les excitacions acústiques en vectors d'ona baixos. També es va obtenir la relació de dispersió de fonons longitudinals i transversals. En tots els casos estudiats, l'amplada del pic, GL,T(q), augmenta amb la freqüència. S'observa una regió lineal a baixos nombres d'ona i una flexió quan s'aproxima el límit de la pseudo-zona de Brillouin. Aquest comportament és el mateix que l'observat experimentalment emprant Inelàstic X-Ray scattering (IXS). La velocitat del so macroscòpica s'obté quan el nombre d'ona tendeix a zero. Els valors obtinguts amb potencials EAM i Morse estan d'acord amb els valors mesurats experimentalment en sistemes de composició similar. El límit Ioffe-Regel (IR) es defineix com la freqüència a la que la longitud de coherència del fonó és similar a la longitud d'ona de fonó. S'observa que la freqüència IR augmenta lleugerament als sistemes més relaxats. El límit IR longitudinal és troba en tots els casos a freqüències superiors a la freqüència del BP. Contràriament als resultats obtinguts en els sistemes LJ, el límit longitudinal IR en Cu20Pd80 y Cu50Pd50 és molt a prop de la posició del BP, mentre que el límit transversal IR és molt per sota d'aquest valor; aquests resultats estan d'acord amb els obtinguts experimentalment per IXS. S'infereix que el potencial EAM augmenta la interacció entre modes longitudinals i l'excés de modes del BP. Finalment s'obtingué la fragilitat en els sistemes estudiats mitjançant el càlcul de la viscositat a temperatures diferents. És conegut experimentalment que la fragilitat augmenta amb la velocitat de refredament. Els sistemes LJ mostraren una fragilitat molt més alta que els Morse i EAM. No obstant això, fins i tot els sistemes simulats amb potencials realistes van mostrar valors de la fragilitat molt superiors als obtinguts experimentalment a causa de l'extrema velocitat extrema de refredament de les simulacions

    El desarrollo de nuevos materiales tiene impacto en todas las áreas de la ingeniería, y en particular en la ingeniería aeronáutica. Los vidrios metálicos son materiales relativamente nuevos, con excelentes propiedades mecánicas; su estudio es imprescindible para su implantación tecnológica. Las propiedades mecánicas macroscópicas de un material están determinadas por su estructura atómica. En particular, la fractura de materiales frágiles se inicia mediante la generación de modos de vibración. En los vidrios metálicos, con estructura amorfa, el espectro vibracional tiene características específicas. En este trabajo es estudian las propiedades vibracionales de los vidrios metálicos usando simulaciones de Dinámica Molecular. Se estudian sistemas binarios utilizando potenciales atómicos de Lennard-Jones (LJ), Morse y Embedded atom method (EAM), de tipo semiempírico. Al igual que en los vidrios metálicos a base de Pd, la relación de las masas de ambas especies en las simulaciones es alta, siendo 2 en potenciales LJ y 1,67 en potenciales Morse y EAM. Las simulaciones a gran escala permiten simular sistemas con heterogeneidades a escala nm, y la simulación a diferente velocidad de enfriamiento permite obtener configuraciones en diferentes estados de relajación. La dinámica de las vibraciones atómicas de los vidrios metálicos es un tema de debate. El origen del exceso de los modos de vibración conocidos como Boson Peak (BP) no es claro. En los sistemas analizados se observa que la dependencia de la posición y la intensitat del BP con el tamaño del sistema es débil. Por el contrario, la intensidad del BP aumenta con la velocidad de enfriamiento, mientras que su posición se desplaza a frecuencias menores. Los resultados obtenidos mediante el uso de potenciales realistas tipo EAM coinciden con los datos experimentales disponibles en vidres de composiciones similares. El factor de estructura dinámica, S (q, ω) se calculó también en sistemas grandes para obtener información sobre el comportamiento de las excitaciones acústicas en vectores de onda bajos. También se obtuvo la relación de dispersión de fonones longitudinales y transversales. En todos los casos estudiados, la anchura del pico, ΓL,T(q), aumenta con la frecuencia. Se observa una región lineal a bajos números de onda y una flexión cuando se aproxima al límite de la pseudo-zona de Brillouin. Este comportamiento es el mismo que el observado experimentalmente por Inelastic X-Ray scattering (IXS). La velocidad macroscópica del sonido se obtiene cuando el número de onda tiende a cero. Los valores obtenidos con potenciales EAM y Morse están en concordancia con los valores medidos experimentalmente en sistemas de composición similar. El límite Ioffer-Regel (IR) se define como la frecuencia a la que la longitud de coherencia del fonón es similar a la longitud de onda del fonón. Se observa que la frecuencia IR aumenta ligeramente en sistemas más relajados. El límite IR longitudinal se encuentra en todos los casos en frecuencias superiores a la frecuencia del BP. Contrariamente a los resultados obtenidos en los sistemas LJ, el límite longitudinal IR en Cu20Pd80 y Cu50Pd50 está muy cerca de la posición del BP, mientras que el límite transversal de IR se encuentra muy por debajo; estos resultados coinciden con los obtenidos experimentalmente mediante IXS. Se infiere que el potencial EAM aumenta la interacción entre los modos longitudinales y el exceso de estados de BP. Finalmente se obtuvo la fragilidad en los sistemas estudiados mediante el cálculo de la viscosidad a diferentes temperaturas. Es conocido experimentalmente que la fragilidad aumenta con la velocidad de enfriamiento. Los sistemas LJ mostraron una fragilidad mucho mayor que los sistemas EAM y Morse. Sin embargo, incluso los sistemas simulados con potenciales realistas mostraron valores de fragilidad muy superiores a los obtenidos experimentalmente debido a las extremas velocidades de enfriamiento de las simulaciones.

  • Molecular dynamics computation of the dynamical structure factor of a Lennard-Jones glass: Propagation of acoustic modes at the nm-scale

     Vallés Sales, Araceli; Derlet, Peter; Crespo Artiaga, Daniel; Pineda Soler, Eloy
    Journal of alloys and compounds
    Vol. 586, p. S250-S253
    DOI: 10.1016/j.jallcom.2012.11.174
    Date of publication: 2014-02-15
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Influence of Cr- and Mo-short-range order in mechanical and corrosion behaviors of amorphous steels: an EXAFS study

     Crespo Artiaga, Daniel; Pineda Soler, Eloy; Madinehei, Seyed Milad; Bruna Escuer, Pere
    Competitive project

     Share

  • Transicions de fase, polimorfisme i dinàmica de la metastabilitat

     Crespo Artiaga, Daniel; Pradell Cara, Trinitat; Buti Papiol, Salvador; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Pineda Soler, Eloy; Bruna Escuer, Pere; Salvado Cabre, Nativitat; Ruiz Martin, Maria Dolores; Macovez, Roberto; Rojas Gregorio, Jose Ignacio; Lloveras Muntane, Pol Marcel; Beltran Sanchidrian, Victòria; Ye, Jin; Liu, Chaoren; Madinehei, Seyed Milad; Mitsari, Efstratia; Molina Giralt, Gloria; Romanini, Michela; Rovira Esteva, Muriel; Tripathi, Pragya; Vispa, Alessandro; Vallés Sales, Araceli; Zachariah, Manesh; Zhai, Fuqiang; Tamarit Mur, Jose Luis
    Competitive project

     Share

  • Relaxation of rapidly quenched metallic glasses: Effect of the relaxation state on the slow low temperature dynamics

     Pineda Soler, Eloy; Bruna Escuer, Pere; Ruta, Beatrice; Gonzalez Silveira, Marta; Crespo Artiaga, Daniel
    Acta materialia
    Vol. 61, num. 8, p. 3002-3011
    DOI: 10.1016/j.actamat.2013.01.060
    Date of publication: 2013-05
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The relaxation spectrum of rapidly quenched Mg65Cu25Y10 metallic glass ribbons is studied by mechanical spectroscopy at temperatures below and around the glass transition. The comparison between hyper-quenched and relaxed samples is used to examine the origin of the low temperature ¿excess wing¿ of internal friction commonly observed in mechanical spectroscopy of metallic glasses. The results show that the excess wing can be attributed to access of the system to the broad a-relaxation process while evidence of secondary relaxations is not found. This suggests that in this glassy system the activation energies of structural relaxation and low temperature deformation are directly related to the activation energy of the main relaxation process of the glassy state.

  • Color and dichroism of silver-stained glasses

     Molina Giralt, Gloria; Murcia, Sonia; Molera Marimon, Judit; Roldan, Clodoaldo; Crespo Artiaga, Daniel; Pradell Cara, Trinitat
    Journal of nanoparticle research
    Vol. 15, num. 9, p. 1-13
    DOI: 10.1007/s11051-013-1932-7
    Date of publication: 2013-08
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Yellow decorations in glasses have been produced since the beginning of the fourteenth century by incorporating metallic silver nanoparticles into the glass (from a few to some tens of nanometers). The optical response of the glass-particles composite is determined by the surface plasmon resonance absorption and scattering of the nanometric metallic particles. Generally, the same color is perceived in reflection and in transmission although dichroic effects are occasionally observed. As silver-stained glasses were designed to be observed in transmission, tuning the transmissioncolor from yellow to red was of technological interest. The relationship between the color observed both in transmission and reflection and the composition and nanostructure of regular (yellow) and dichroic (yellow and red) silver stains from the Renaissance (late fifteenth and sixteenth century, respectively) is related do the presence of a layer (of about 10¿20 lm thick) of metallic silver nanoparticles (from few to 100 nm in size). The correlation between the colors observed and the silver stain nanostructure is studied with particular emphasis on the origin of the dichroic behavior. The optical response is computed and compared to the experimental data. Differences in the synthesis parameters responsible for the colors and for the dichroic behavior of the silver stain glasses are proposed. This is essential for the replication of the glass pieces which are required as replacements in the restoration/conservation of the windows but is also of broader interest.

  • Element-Resolved Corrosion Analysis of Stainless-Type Glass-Forming Steels

     Duarte, Maria Jazmin; Klemm, Julia; Klemm, S.O.; Mayrhofer, K. J. J.; Stratmann, M.; Borodin, S.; Romero, A.H.; Madinehei, Seyed Milad; Crespo Artiaga, Daniel; Serrano, J.; Gerstl, S. S. A.; Choi, Pyuck-Pa; Raabe, Dierk; Renner, Frank U.
    Science
    Vol. 341, num. 6144, p. 372-376
    DOI: 10.1126/science.1230081
    Date of publication: 2013-07-26
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Ultrathin passive films effectively prevent the chemical attack of stainless steel grades in corrosive environments; their stability depends on the interplay between structure and chemistry of the constituents iron, chromium, and molybdenum (Fe-Cr-Mo). Carbon (C), and eventually boron (B), are also important constituents of steels, although in small quantities. In particular, nanoscale inhomogeneities along the surface can have an impact on material failure but are still poorly understood. Addressing a stainless-type glass-forming Fe50Cr15Mo14C15B6 alloy and using a combination of complementary high-resolution analytical techniques, we relate near-atomistic insights into increasingly inhomogeneous nanostructures with time- and element-resolved dissolution behavior. The progressive elemental partitioning on the nanoscale determines the degree of passivation. A detrimental transition from Cr-controlled passivity to Mo-controlled breakdown is dissected atom by atom, demonstrating the importance of nanoscale knowledge for understanding corrosion.

    Ultrathin passive films effectively prevent the chemical attack of stainless steel grades in corrosive environments; their stability depends on the interplay between structure and chemistry of the constituents iron, chromium, and molybdenum (Fe-Cr-Mo). Carbon (C), and eventually boron (B), are also important constituents of steels, although in small quantities. In particular, nanoscale inhomogeneities along the surface can have an impact on material failure but are still poorly understood. Addressing a stainless-type glass-forming Fe50Cr15Mo14C15B6 alloy and using a combination of complementary high-resolution analytical techniques, we relate near-atomistic insights into increasingly inhomogeneous nanostructures with time- and element-resolved dissolution behavior. The progressive elemental partitioning on the nanoscale determines the degree of passivation. A detrimental transition from Cr-controlled passivity to Mo-controlled breakdown is dissected atom by atom, demonstrating the importance of nanoscale knowledge for understanding corrosion

  • Relaxation processes in metallic glasses studied by mechanical spectroscopy

     Crespo Artiaga, Daniel; Liu, Chaoren; Bruna Escuer, Pere; Pineda Soler, Eloy
    International Discussion Meeting on Relaxation in Complex Systems
    p. 218-
    Presentation's date: 2013-07-24
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Mechanical spectroscopy plays in metallic glasses (MG) a role similar to dielectric spectroscopy in dielectric glasses. Here we analyse the low frequency relaxation properties of two MG by mechanical spectroscopy. Mg65Cu25Y10 MG ribbons are analysed by mechanical spectroscopy at temperatures below and around the glass transition. Hyper-quenched and relaxed samples show different temperature dependencies of the internal friction, shown in different excess wings in their mechanical spectra. The analysis of these low temperature excess wings is performed in terms of the a-relaxation behaviour in and out of equilibrium, while evidence of secondary relaxation is not found [1]. This suggests that, in this glassy system, the activation energies of structural relaxation and low temperature deformation are directly related to the activation energy of the main relaxation process of the glassy state. Zr46Al8Cu46 is also analysed. Characteristic relaxation times measured from direct mechanical relaxation experiments below the glass transition are compared to relaxation times determined by mechanical spectroscopy in the glass region, showing excellent agreement. The effect of different relaxation protocols on the characteristic relaxation times is unveiled. [1] E. Pineda, P. Bruna, B. Ruta, M. Gonzalez-Silveira, D. Crespo, Relaxation of rapidly quenched metallic glasses: Effect of the relaxation state on the slow, low temperature dynamics, Acta Materialia, in press (2013).

  • Kinetics of crystallization and multiphase microstructural evolution of glass-forming steels

     Duarte, Maria Jazmin; Choi, Pyuck-Pa; Kostka, Aleksander; Crespo Artiaga, Daniel; Bruna Escuer, Pere; Raabe, Dierk; Renner, Frank U.
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    Presentation's date: 2013-07-01
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Vidres metàl·lics, Cristalització

  • Microstructural characterization and corrosion resistance of Fe-based bulk metallic glasses with Cr addition

     Madinehei, Seyed Milad; Bruna Escuer, Pere; Pineda Soler, Eloy; Crespo Artiaga, Daniel
    International Discussion Meeting on Relaxation in Complex Systems
    p. 212-
    Presentation's date: 2013-07-21
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Amorphous steels can be obtained in a wide range of compositions, being the presence of Cr and Mo a key ingredient to produce Fe-based bulk metallic glasses without rare earth additions, thus lowering the economical costs of production. Therefore, it is crucial to have a detailed description of the Cr and Mo effects on the structure. Moreover, local changes in the structure can substantially modify some macroscopic properties of the alloy such as the corrosion resistance. In this work we present a detailed microstructural study of FeMoCrCB amorphous steel with several relative amounts of Fe/Cr. Transmission electron microscopy and electron diffraction pattern teachniques have been used to completely characterize the crystallization process of these alloys. The use of atom-probe tomography allowed us to follow the local changes in the amorphous matrix during the crystallization process and to relate them with the results obtained from corrosion resistance tests performed by means of electrochemical measurements. The different corrosion resistance of the as-quenched samples and the partially crystallized ones is discused in terms of the structural and chemical changes in the amorphous matrix, thus allowing us to determine the optimal amount of Cr needed to improve the macroscopic properties of this family of Fe-based bulk metallic glasses.

  • Molecular dynamics simulation of metallic glasses: Effect of the relaxation state on the Boson Peak

     Vallés Sales, Araceli; Pineda Soler, Eloy; Derlet, Peter; Crespo Artiaga, Daniel
    International Discussion Meeting on Relaxation in Complex Systems
    p. 224-
    Presentation's date: 2013-07-21
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Glasses, in general, and metallic glasses (MG), in particular, show an excess of vibrational modes above the Debye level, in what is commonly termed as Boson Peak (BP). Structural and elastic heterogeneities at the nm scale is an intrinsic feature of glasses. These heterogeneities determine the physical properties in the nm-scale region, this is the transition region between the atomic level, defined by the particular atomic bonding and packing of the substance, and the macroscopic elastic continuum. The BP and the anomalies in the acoustic modes with nm-scale wavelengths are two of the main measurable physical aftermaths of this mesoscale region. The study of the features of the BP in metallic glasses is particularly interesting due to the simplicity of the interatomic potentials. Thus molecular dynamics (MD) simulations of MG are particularly affordable. We performed large scale MD simulations in binary MG by using both Lennard-Jones and more realistic embedded atom method (EAM) potentials. Different quenching rates allowed us to access different relaxation states in our simulated MG. The relation of dispersion and the vibrational density of states are computed, and the features of the BP are analysed. Here we will discuss the differences between the BP in LJ and EAM MGs, as well as the effect of the relaxation state. A discussion on the effect of the fragility of the glass will be also presented. [1] A. Vallés, P. Derlet, D. Crespo & E. Pineda, J. Alloys & Comp., in press (2013), available online DOI: 10.1016/j.jallcom.2012.11.174.

  • Structural relaxation, aging and mechanical flow in Cu46Zr46Al8 metallic glass

     Liu, Chaoren; Pineda Soler, Eloy; Crespo Artiaga, Daniel
    International Discussion Meeting on Relaxation in Complex Systems
    p. 10-
    Presentation's date: 2013-07-21
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The structural relaxation times t of Cu46Zr46Al8 glass were measured above and below glass transition by mechanical relaxation. DMA multi-frequency tests and static stress-relaxation tests allowed us to characterize the structural relaxation time behaviour in a wide range of temperatures. Similarly to recent results in the MgCuY system [1], the experimental results can be well interpreted by Vogel-Fucher-Tammann and Arrhenius models in liquid and glassy states respectively. The interpretation of DMA measurements within this relaxation scheme shows no evidence of secondary relaxation in the frequency window explored. The analysis is performed for different glassy states, in a different degree of relaxation, achieving a good description of structural relaxation and aging in this system. The activation energy of structural relaxation in the glassy state is found to be correlated with the activation energy of mechanical flow. The consequences of such correlation for the everlasting search of ductile metallic glasses are also discussed. [1] E. Pineda, P. Bruna, B. Ruta, M. Gonzalez-Silveira, D. Crespo, Relaxation of rapidly quenched metallic glasses: Effect of the relaxation state on the slow, low temperature dynamics, Acta Materialia, in press (2013).

  • Inelastic X-ray scattering in metallic glasses

     Bruna Escuer, Pere; Serrano, Jorge; Pineda Soler, Eloy; Duarte, Maria Jazmin; Zhao, Kun; Wang, Wei Hua; Crespo Artiaga, Daniel
    Intermetallics
    Vol. 30, num. SI, p. 148-153
    Date of publication: 2012-11
    Journal article

     Share Reference managers Reference managers Open in new window

  • Microstructural Characterization & Viscoelastic Properties of AlZnMg & AlCuMg Alloys  Open access

     Rojas Gregorio, Jose Ignacio
    Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The comprehension of the viscoelastic behaviour of metals is of high interest as these materials are subjected to dynamic loads in most of their structural applications, and also because it enables a deeper understanding of several technologically essential properties, like mechanical damping and yielding. Thus, research on this field is needed not only because it may lead to new potential applications of metals, but also because predictability of the fatigue response may be greatly enhanced. Indeed, fatigue is the consequence of microstructural effects induced in a material under dynamic loading, while the viscoelastic behaviour is also intimately linked to the microstructure. Accordingly, the characterization of the viscoelastic response of a material offers an alternative method for analysing its microstructure and ultimately its fatigue behaviour. This research is aimed at the identification, characterization and modelling of the effects of temperature, excitation frequency and microstructure/phase transformations (when present) on the viscoelastic behaviour of aluminium alloys AA 7075-T6 and AA 2024-T3, and of pure aluminium in the H24 temper. The identification of the mechanical relaxation processes taking place and the relation between the viscoelastic response of AA 7075-T6 and AA 2024-T3 and the fatigue behaviour will be attempted for all these materials. Finally, we intend to investigate possible influences of the dynamic loading frequency on fatigue, and especially the existence of a threshold frequency marking the transition from a static-like response of the material to the advent of fatigue problems. AA 7075-T6 and AA 2024-T3 were selected for this study because these alloys are key representatives of their important families and are highly suitable to a number of industrial applications in the aerospace sector and transport industry. Pure aluminium was selected because of the inherent interest of this metal, for comparison purposes and for discussing the phenomena observed for the alloys. To accomplish the objectives, the viscoelastic response of the materials was measured experimentally with a Dynamic- Mechanical Analyser (DMA). The results were combined with Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC). An analytical model was proposed which fits the storage modulus up to 300 ºC. The model takes into account the effect of temperature, the excitation frequency and the concentration of some precipitates for the alloys. This allows us to test models proposed for the reaction rates of the associated microstructural transformations, to determine their kinetic parameters and to characterize their influence on the viscoelastic behaviour, showing that the DMA is a good tool for studying the material microstructure, phase transformation kinetics and the influence of transformations on the viscoelastic properties of materials. The Time-Temperature Superposition (TTS) principle has been successfully applied to the DMA data, providing master curves for the storage and loss moduli. Also, it is proposed that the decrease of yield and fatigue strength with temperature observed in some aluminium alloys may be due to the internal friction increase with temperature. Finally, the existence of a threshold frequency is suggested, below which materials subjected to dynamic loading exhibit a static-like, elastic response, such that creep mechanisms dominate and deterioration due to fatigue may be neglected. A procedure to estimate this transition frequency is proposed.

    La comprensión del comportamiento visco-elástico de los metales es de gran interés ya que estos están sometidos a cargas dinámicas en la mayoría de sus aplicaciones estructurales, y también porque posibilita un conocimiento más profundo de varias propiedades esenciales tecnológicamente, como el amortiguamiento mecánico y el límite elástico. Así, la investigación en este campo es necesaria no sólo porque puede conducir hacia nuevas aplicaciones potenciales de los metales, sino también porque la capacidad de predecir el comportamiento en fatiga de los mismos puede verse ampliamente mejorada. De hecho, la fatiga de los metales es consecuencia de efectos microestructurales inducidos en el material bajo cargas dinámicas, y el comportamiento visco-elástico está también íntimamente relacionado con la microestructura. Así, la caracterización de la respuesta visco-elástica de un material ofrece un método alternativo para analizar su microestructura y, en último término, su respuesta en fatiga. Este trabajo tiene por objetivos la identificación, caracterización y modelización de los efectos de la temperatura, la frecuencia de excitación y la microestructura/transformaciones de fase en el comportamiento visco-elástico de las aleaciones de aluminio AA 7075-T6 y AA 2024-T3, y de aluminio puro en estado H24. Se aborda también la identificación de los procesos de relajación mecánicos que tienen lugar en estos materiales y la identificación de la relación entre el comportamiento visco-elástico de AA 7075-T6 y 2024-T3 y su respuesta en fatiga. Finalmente, se intentará investigar posibles influencias de la frecuencia de la carga dinámica en la fatiga, y en especial la existencia de una frecuencia umbral que marque la transición desde una respuesta cuasi-estática del material hacia la aparición de problemas de fatiga. AA 7075-T6 y AA 2024-T3 fueron seleccionadas porque son representantes clave de sus importantes familias de aleaciones, y son altamente adecuadas para un gran número de aplicaciones en los sectores aeroespacial y del transporte. El aluminio puro fue seleccionado para este estudio por su interés inherente, y para realizar comparaciones y discutir algunos de los fenómenos observados en las aleaciones. Para cumplir los objetivos, el comportamiento visco-elástico de los materiales fue medido experimentalmente con un Dynamic-Mechanical Analyser (DMA). Los resultados se combinaron con microscopía electrónica y calorimetría. Se propuso un modelo analítico que ajusta la componente real del módulo elástico dinámico (el storage modulus) hasta 300 ºC. El modelo toma en consideración los efectos de la temperatura, la frecuencia de la carga dinámica y la concentración de ciertos precipitados para el caso de las aleaciones. Esto permitió testear modelos propuestos para las velocidades de reacción de las transformaciones microestructurales asociadas, determinar sus parámetros cinéticos y caracterizar su influencia en el comportamiento visco-elástico, demostrando que el DMA es una buena herramienta para estudiar la microestructura del material, la cinética de las transformaciones de fase y la influencia de las transformaciones en las propiedades visco-elásticas de los materiales. El principio de superposición de tiempo y temperatura ha sido aplicado con éxito, proporcionando curvas maestras para las componentes del módulo elástico dinámico. Asimismo, se sugiere que el descenso en el límite elástico y la resistencia a fatiga con la temperatura observado en algunas aleaciones de aluminio puede ser debido al incremento de la fricción interna con la temperatura. Finalmente, se propone la existencia de una frecuencia umbral, por debajo de la cual los materiales sometidos a cargas dinámicas exhiben una respuesta cuasi-estática y elástica, de tal modo que mecanismos de termofluencia son dominantes y el deterioro del material debido a fatiga puede ser despreciado. Se propone un procedimiento para estimar esta frecuencia de transición.

  • Stability in air of silver and silver oxide nanoparticle shells deposited over silica spheres without using coupling agents

     Flores, Juan Carlos; Crespo Artiaga, Daniel; Torres, Victor; Carmona, J; Rainforth, W.M.; Zhou, Z.; Calderon Moreno, J.M.
    Journal of nanoscience and nanotechnology
    Vol. 12, num. 10, p. 8158-8164
    DOI: 10.1166/jnn.2012.4516
    Date of publication: 2012-10
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Modeling of the effect of temperature, frequency, and phase transformations on the viscoelastic properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys  Open access

     Rojas Gregorio, Jose Ignacio; Crespo Artiaga, Daniel
    Metallurgical and materials transactions A-Physical metallurgy and material
    Vol. 43, p. 4633-4646
    DOI: 10.1007/s11661-012-1281-7
    Date of publication: 2012-12-01
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The viscoelastic response of commercial aluminum alloys 7075-T6 and 2024-T3 as a function of temperature is presented. Experimental data are obtained with a dynamic-mechanical analyzer (DMA) at different loading frequencies and compared with the available transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) data. The effect of successive microstructural transformations (particle precipitation and redissolution) is revealed. An ana- lytical model is developed, which fits the mechanical response up to 573 K (300 C). The model takes into account the concentration of Guinier-Preston Zones (GPZ) and metastable precipi- tates ( g ¢ in AA 7075-T6 and h ¢ /S ¢ in AA 2024-T3), allowing us to determine the kinetic parameters of these transformations. The activation energies were previously obtained by sev- eral authors from DSC measurements and other techniques, showing considerable dispersion. The presented data, obtained with a completely different technique, allow us to reduce the uncertainty on these data and show the potential of DMA measurements in the study of microstructural transformations.

  • Molecular dynamics computation of the dynamical structure factor of metallic glasses

     Derlet, Peter; Vallés Sales, Araceli; Crespo Artiaga, Daniel; Pineda Soler, Eloy
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    p. 73
    Presentation's date: 2012-06-19
    Presentation of work at congresses

    Read the abstract Read the abstract  Share Reference managers Reference managers Open in new window

    The collective vibrational atomic dynamics of metallic glasses is a longstanding subject of debate. The origin of the excess of vibrational modes known as the Boson Peak is not clear, though it appears to be connected to the so-called quasi-localized eigen-modes of the vibrational spectrum. However, it has not yet shown if this is a universal phenomenon affecting all classes of glasses. Computation of the dynamical structure factor by molecular dynamics (MD) may allow us to analyse the factors influencing the features of the Boson Peak. Here we report a procedure to compute the vibrational density of states (VDOS), which was used to analyse the vibrational spectrum of Lennard-Jones glasses. We compute the velocity self-correlation function, and from that the VDOS by Fourier transform. In a similar way, via the current-current correlation function, we also obtain the dynamic structure factor. In order to reach the momentum values accessible experimentally, MD simulations must be performed in large enough boxes. Furthermore, the atomic dynamics must be recorded for times long enough so as to gain access to the experimental energy spectrum regime, thus implying a large computational effort. Results of this simulation will be compared to those obtained via exact diagonalization methods (Derlet et al, Eur. J. Phys. B (in press), 2012) as well as to experimental data from Inelastic Scattering.

  • Role of Cr in the local structure and corrosion properties of amorphous steels

     Pineda Soler, Eloy; Madinehei, Seyed Milad; Bruna Escuer, Pere; Crespo Artiaga, Daniel
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    p. 287
    Presentation's date: 2012-06-20
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Determination of wind speed and associated loads over the sports facility collapsed during the severe windstorm of 24 January 2009 in Sant Boi de Llobregat (Barcelona)  Open access

     Mazon Bueso, Jordi; Crespo Artiaga, Daniel; Pino Gonzalez, David
    Tethys: Journal of Mediterranean Meteorology and Climatology
    DOI: 10.3369/tethys.2011.8.07
    Date of publication: 2011-06-23
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The severe windstorm of 24 January 2009, caused by an explosive cyclogenesis, affected coastal and precoastal areas of the northeast of the Iberian Peninsula, where damages were numerous and significant, both in urban areas and in forests. One of the most important effects was the collapse of a sports facility in Sant Boi de Llobregat (10 km southwest of Barcelona), killing four children. The objective of this study is to estimate the wind speed over the sports facility and calculate the suction of the wind on the roof of the building, and the consequent collapse of the walls. To get a first approximation, a simulation of the episode around the time of maximum wind gust was inspected using the mesoscale model MM5. In the second part, the damage around the collapsed facility was analyzed, with which we note the fact that a truck was dragged and knocked over by the wind. This analysis allows for the conclusion that, in conjunction with the maximum wind gust, there was a sudden and very local shift in the wind, which caused the gust to hit the building head on. Based on this observation, the wind speed on surface and at 7 m (roof of the building) was estimated, and the suction of the wind was calculated

  • Effect of temperature and frequency of dynamic loading in the viscoelastic properties of aluminium alloy 7075-T6

     Rojas Gregorio, Jose Ignacio; Aguiar, Albert; Crespo Artiaga, Daniel
    Physica status solidi C. Current topics in solid state physics
    Vol. 8, num. 11-12, p. 3111-3114
    DOI: 10.1002/pssc.201000732
    Date of publication: 2011-06-24
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Polyamorphic transitions in Ce-based metallic glasses by synchrotron radiation

     Duarte Correa, Maria Jazmin; Bruna Escuer, Pere; Pineda Soler, Eloy; Crespo Artiaga, Daniel; Garbarino, Gaston; Verbeni, Roberto; Zhao, Kun; Wang, Wei Hua; Romero, Aldo H; Serrano Gutierrez, Jorge
    Physical review B: condensed matter and materials physics
    Vol. 84, num. 22, p. 224116
    DOI: 10.1103/PhysRevB.84.224116
    Date of publication: 2011-12-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Communication: Are metallic glasses different from other glasses? A closer look at their high frequency dynamics

     Bruna Escuer, Pere; Baldi, Giacomo; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Suck, J.B.; Crespo Artiaga, Daniel; Monaco, Giulio
    Journal of chemical physics
    Vol. 135, num. 10, p. 1-4
    DOI: 10.1063/1.3640002
    Date of publication: 2011-09-14
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Acoustic properties of metallic glasses in the mesoscopic regime by inelastic X-ray scattering

     Bruna Escuer, Pere; Baldi, Giacomo; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Crespo Artiaga, Daniel; Monaco, Giulio
    Journal of alloys and compounds
    Vol. 509, p. S95-S98
    DOI: 10.1016/j.jallcom.2010.09.065
    Date of publication: 2011-06
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Role of Mo in the local configuration and structure stabilization of amorphous steels, a Synchrotron X-ray diffraction and Mossbauer study

     Pineda Soler, Eloy; Bruna Escuer, Pere; Serrano, Jordi; Torrens Serra, Joan; Crespo Artiaga, Daniel
    Journal of alloys and compounds
    Vol. 509S, p. S56-S59
    DOI: 10.1016/j.jallcom.2011.02.019
    Date of publication: 2011-07
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Amorphous steels are promising materials with potential structural applications. The glass-forming ability (GFA) and mechanical properties of metallic glasses are intimately related to the local structure. In Fe-based alloys, Cr andMocontentseemto play a key role in stabilizing the amorphous atomic-level structure. Here we present a study on the effects of changing Mo content in Fe72−xC7Si3.3B5.5P8.7Cr2.3Al2Mox amorphous steels.Westudy the local structure of these alloys by Synchrotron X-ray diffraction and Mössbauer spectroscopy. The results show how the amorphous phase evolves from a ferromagnetic Fe-rich structure to a structure with predominance of paramagnetic environments with the increase of Mo content. The changes in the distribution of magnetic environments cannot be attributed only to the Fe–Mo substitution but to a change of local configuration in the amorphous phase.

  • Producción de vidrios metálicos masivos. Estudio de la estructura local y estabilidad para la mejora de propiedades mecánicas 2

     Pineda Soler, Eloy; Bruna Escuer, Pere; Rojas Gregorio, Jose Ignacio; Jove Casulleras, Roger; Vallés Sales, Araceli; Renner, Frank U.; Madinehei, Seyed Milad; Crespo Artiaga, Daniel
    Competitive project

     Share

  • Access to the full text
    Tensegrity ring for a sports arena formfinding and testing  Open access

     Peña Villamil, Diana Maritza; Llorens Duran, Josep Ignasi de; Sastre Sastre, Ramon; Crespo Artiaga, Daniel; Tristancho Martinez, Joshua
    International Conference on Textile Composites and Inflatable Structures
    p. 1-8
    Presentation's date: 2011
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The current prototype¿s key contribution to the field of light-weight structures is that it is the first time that a pure tensegrity ring has been used in place of a compression ring. This design features a cladding structure for a sports arena, which consist of a ring-shaped outer section and a central roof structure. The ring-shaped outer section of the stadium consists of a tensegrity structure, which uses textile membranes in a place of conventional tension cables to bear the tensile forces occurring between the pressure elements. The supporting framework and spatial enclosure therefore become one an extension to the tension integrity principle. The central area of the roof is covered over by a Geiger dome, which in turn is a specific version of the tensegrity principle.

    The current prototype’s key contribution to the field of light-weight structures is that it is the first time that a pure tensegrity ring has been used in place of a compression ring. This design features a cladding structure for a sports arena, which consist of a ring-shaped outer section and a central roof structure. The ring-shaped outer section of the stadium consists of a tensegrity structure, which uses textile membranes in a place of conventional tension cables to bear the tensile forces occurring between the pressure elements. The supporting framework and spatial enclosure therefore become one an extension to the tension integrity principle. The central area of the roof is covered over by a Geiger dome, which in turn is a specific version of the tensegrity principle.

  • Inelastic X-ray Scattering in metallic glasses

     Bruna Escuer, Pere; Serrano Gutierrez, Jorge; Pineda Soler, Eloy; Duarte Correa, Maria Jazmin; Zhao, Kun; Wang, Wei Hua; Crespo Artiaga, Daniel
    International Conference on Bulk Metallic Glasses
    p. 129
    Presentation's date: 2011-05-16
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Fragility measurement of Pd-based metallic glass by dynamic mechanical analysis

     Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Bruna Escuer, Pere; Crespo Artiaga, Daniel
    Journal of alloys and compounds
    Vol. 504S, p. 215-218
    DOI: 10.1016/j.jallcom.2010.02.065
    Date of publication: 2010-08
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The measurement of fragility of glass-forming liquids involves either the determination of viscosity at different temperatures above the glass transition or the measurement of the dynamic glass–liquid transition by calorimetry or dilatometry at different heating rates. Significant data dispersion is observed when comparing fragility parameters obtained by different techniques. Dynamic mechanical analysis (DMA) is widely used for characterizing glass transition in polymer science while it is still seldom used in metallic glasses. In this work we determine the relaxation time ( ) vs temperature of a Pd77.5Si16.5Cu6 glass by means ofDMAmeasurements. The measured range of relaxation times cover the whole region from glass transition ( > 100 s) to times of the order of 10−2 s. The fragility parameter obtained for this alloy is found significantly higher than the values obtained from previous viscosity and calorimetric techniques. The application range, limitations and correctness of the technique are discussed.

  • High frequency dynamics of BMG determined by synchrotron radiation: A microscopic picture

     Serrano Gutierrez, Jorge; Pineda Soler, Eloy; Bruna Escuer, Pere; Labrado, Anna; Le Tacon, Mathieu; Krisch, M.; Monaco, Giulio; Crespo Artiaga, Daniel
    Journal of alloys and compounds
    Vol. 495, num. 2, p. 319-322
    DOI: 10.1016/j.jallcom.2009.10.250
    Date of publication: 2010-04-16
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Influence of Cr- and Mo-short-range order in ductility and mechanical properties of amorphous steels: an EXAFS study.

     Bruna Escuer, Pere; Serrano Gutierrez, Jorge; Pineda Soler, Eloy; Crespo Artiaga, Daniel; Pradell Cara, Trinitat
    Competitive project

     Share

  • Glass forming ability and thermal stability of BMG's based on common metals

     Crespo Artiaga, Daniel; Bruna Escuer, Pere; Labrador, A.; Pineda Soler, Eloy
    Competitive project

     Share

  • Glass forming ability of BMG's based on common metals

     Crespo Artiaga, Daniel; Bruna Escuer, Pere; Pineda Soler, Eloy; Labrador, A.
    Competitive project

     Share

  • Elastic constants determination of metallic glasses with marginal glass-forming ability

     Pineda Soler, Eloy; Bruna Escuer, Pere; Crespo Artiaga, Daniel
    Competitive project

     Share

  • Effect of temperature and frequency of dynamic loading in viscoelastic properties of aluminium alloys AA 2024-T3 and 7075-T6

     Rojas Gregorio, Jose Ignacio; Crespo Artiaga, Daniel; Aguiar, Antonio
    International Workshop on Non-Crystalline Solids
    Presentation's date: 2010-04-21
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Electrical resistivity study of a rare earth-based metallic glass under pressure

     Garbarino, Gaston; Bruna Escuer, Pere; Pineda Soler, Eloy; Duarte Correa, Maria Jazmin; Serrano Gutierrez, Jorge; Crespo Artiaga, Daniel; Nunez-Regueiro, M.
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    p. 26
    Presentation's date: 2010-07-05
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Role of Cr and Mo in the local configuration and structure stabilization of amorphous steels

     Bruna Escuer, Pere; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Crespo Artiaga, Daniel
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    p. 100
    Presentation's date: 2010-07-07
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Mo microalloying of amorphous steels: stability of the atomic structure and effects ob glass transition and crystallization processes of Fe71.2-x(C-Si-B-P-Cr-Al)-Mox alloys

     Bruna Escuer, Pere; Vallés, Araceli; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Crespo Artiaga, Daniel
    International Workshop on Non-Crystalline Solids
    p. 65
    Presentation's date: 2010-04-21
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Study of acoustic excitations in metallic glasses

     Bruna Escuer, Pere; Baldi, Giacomo; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Duarte Correa, Maria Jazmin; Crespo Artiaga, Daniel; Monaco, Giulio
    International Workshop on Non-Crystalline Solids
    p. 51-52
    Presentation's date: 2010-04-21
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Inelastic X-ray scattering in metallic glasses

     Bruna Escuer, Pere; Baldi, Giacomo; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Duarte Correa, Maria Jazmin; Crespo Artiaga, Daniel; Monaco, Giulio
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    p. 111
    Presentation's date: 2010-07-08
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Formfinding and structures analysis of a tensegrity dome

     Peña, Diana; Llorens Duran, Josep Ignasi de; Sastre Sastre, Ramon; Crespo Artiaga, Daniel; Tristancho Martinez, Joshua
    Sysmposium of the International Association for Shell and Spatial Structures
    p. 1-9
    Presentation's date: 2010-11-10
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Anàlisi de l¿episodi de vent sever del 24 de gener del 2009 a Sant Boi del Llobregat  Open access

     Mazon Bueso, Jordi; Crespo Artiaga, Daniel; Pino Gonzalez, David
    Jornades de Meteorologia i Climatologia de la Mediterrània Occidental
    p. 1-2
    Presentation's date: 2010-03-11
    Presentation of work at congresses

    Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

  • Cobalt nanocrystallites encapsulated in boron nitride shells

     Calderon Moreno, Jose Maria; Pradell Cara, Trinitat; Crespo Artiaga, Daniel; Popa, M; Narita, I; Oku, T
    Materials science and engineering B. Solid state materials for advanced tech
    Vol. 162, num. 2, p. 106-110
    Date of publication: 2009-05
    Journal article

     Share Reference managers Reference managers Open in new window

  • Deposition of Silver Nanoshell and Reactivity of Silver Nanoparticles with Surface Silanols of Submicrospherical Silica

     Flores, Jc; Torres, V; Popa, M; Crespo Artiaga, Daniel; Calderon Moreno, Jose Maria
    Journal of nanoscience and nanotechnology
    Vol. 9, num. 5, p. 3177-3180
    Date of publication: 2009-05
    Journal article

     Share Reference managers Reference managers Open in new window

  • Structural study of conventional and bulk metallic glasses during annealing

     Pineda Soler, Eloy; Hidalgo, I; Bruna Escuer, Pere; Pradell Cara, Trinitat; Labrador, A.; Crespo Artiaga, Daniel
    Journal of alloys and compounds
    Vol. 483, p. 578-581
    DOI: 10.1016/j.jallcom.2008.07.194
    Date of publication: 2009-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Phase-field modelling of microstructural evolution in primary crystallization

     Bruna Escuer, Pere; Pineda Soler, Eloy; Crespo Artiaga, Daniel; Rojas Gregorio, Jose Ignacio
    Journal of alloys and compounds
    Vol. 483, num. 1-2, p. 645-649
    DOI: 10.1016/j.jallcom.2008.07.215
    Date of publication: 2009-08-26
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • BiFeO3 films on steel substrate by the citrate method

     Popa, M; Preda, S; Fruth, V; Sedlackova, K; Balazsi, C; Crespo Artiaga, Daniel
    Thin solid films
    Vol. 517, num. 8, p. 2581-2585
    Date of publication: 2009-02
    Journal article

     Share Reference managers Reference managers Open in new window

  • Preliminary evaluation of small angle elastic scattering and amorphous character of Ce55Al45 metallic glass-forming alloy

     Crespo Artiaga, Daniel; Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Bruna Escuer, Pere
    Competitive project

     Share

  • Producción de vidrios metálicos masivos. Estudio de la estructura local y estabilidad para la mejora de propiedades mecánicas

     Crespo Artiaga, Daniel; Bruna Escuer, Pere; Rojas Gregorio, Jose Ignacio; Pineda Soler, Eloy; Pradell Cara, Trinitat; Serrano Gutierrez, Jorge; Labrador, A.; Garrido Galera, Victor; Torres Heredia, Victor Elias; Flores Garcia, Juan Carlos
    Competitive project

     Share

  • Microstructure description from the differential Avrami formulation

     Crespo Artiaga, Daniel; Bruna Escuer, Pere; Pineda Soler, Eloy; Pradell Cara, Trinitat
    Reviews on advanced materials science
    Vol. 18, p. 459-463
    Date of publication: 2008-05
    Journal article

     Share Reference managers Reference managers Open in new window

  • Single phase MnFe2O4 powders obtained by the polymerized complex method

     Popa, M; Bruna Escuer, Pere; Crespo Artiaga, Daniel; Moreno, Jose Maria
    Journal of the American Ceramic Society
    Vol. 91, num. 8, p. 2488-2494
    Date of publication: 2008-08
    Journal article

     Share Reference managers Reference managers Open in new window