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  • DISSENY, IMPLEMENTACIÓ I AVALUACIÓ DE PROPOSTES DE FEEDFORWARD SOSTENIBLE

     Pelayo Melero, Ignacio Manuel; Cano, Elena; Valero Baya, Jordi; Fabregat Fillet, Jaime; Ornat Longarón, César; Achaerandio Puente, Maria Isabel; Buenestado Caballero, Pablo; Pineda Soler, Eloy
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  • 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
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  • 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

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    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.

  • 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

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    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.

  • 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

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    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).

  • 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

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    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

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    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).

  • Universal physical aging in metallic glasses at the atomic length scale

     Ruta, Beatrice; Baldi, Giacomo; Bruna Escuer, Pere; Chushkin, Y.; Pineda Soler, Eloy
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    Presentation's date: 2013-07-02
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  • 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

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    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.

  • 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

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  • Atomic-scale relaxation dynamics and aging in a metallic glass probed by X-ray photon correlation spectroscopy

     Ruta, Beatrice; Chushkin, Y.; Monaco, Giulio; Cipelletti, L.; Pineda Soler, Eloy; Bruna Escuer, Pere; Giordano, V.; Gonzalez Silveira, Marta
    Physical review letters
    Vol. 109, num. 16
    DOI: 10.1103/PhysRevLett.109.165701
    Date of publication: 2012-10-17
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  • 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
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    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.

  • Relaxation dynamics and aging in metallic glasses: a direct view at the atomic scale

     Ruta, Beatrice; Chushkin, Y.; Bruna Escuer, Pere; Pineda Soler, Eloy; Monaco, Giulio
    International Symposium on Metastable, Amorphous and Nanostructured Materials
    p. 62
    Presentation's date: 2012-06-18
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  • 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

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  • Relaxation dynamics and aging in structural glasses

     Ruta, Beatrice; Chushkin, Y.; Monaco, Giulio; Cipelletti, L.; Giordano, V.; Pineda Soler, Eloy; Bruna Escuer, Pere
    International Symposium on Slow Dynamics in Complex Systems
    p. 181-188
    DOI: 10.1063/1.4794566
    Presentation's date: 2012-12
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  • 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

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  • 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

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    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.

  • 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

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  • 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
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  • Study of the acoustic modes in a strong metallic glass by means of Inelastic X-ray Scattering

     Pineda Soler, Eloy; Bruna Escuer, Pere; Derlet, Peter; Baldi, Giacomo
    Competitive project

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  • 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

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  • Study of devitrification process in Fe-base bulk metallic glasses

     Pineda Soler, Eloy; Bruna Escuer, Pere
    Competitive project

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  • 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

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  • 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

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    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
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  • 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

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

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

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  • 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

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

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

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  • 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

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  • 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

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  • 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

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  • 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

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  • 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

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  • TRANSICIONS DE FASES, POLIMORFISME I DINÀMICA DE LA METAESTABILITAT

     Duarte Correa, Maria Jazmin; Rojas Gregorio, Jose Ignacio; Crespo Artiaga, Daniel; Torra Ferre, Vicenç; Pineda Soler, Eloy; Buti Papiol, Salvador; Salvado Cabre, Nativitat; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Ruiz Martin, Maria Dolores; Rovira Esteva, Muriel; Levit Valenzuela, Rafael; Veglio, Nestor Raul; Romanini, Michela; Macovez, Roberto; Flores Garcia, Juan Carlos; Torres Heredia, Victor Elias; Martinez Garcia, Julio Cesar; Serrano Gutierrez, Jorge; Molera Marimon, Judit; Tamarit Mur, Jose Luis
    Competitive project

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  • Dynamical signatures of pressure induced polyamorphism in Ce55Al45 metallic glass

     Pineda Soler, Eloy; Pradell Cara, Trinitat; Serrano Gutierrez, Jorge
    Competitive project

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  • 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

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  • 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

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  • 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

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  • Temporal evolution of the domain structure in a Poisson-Voronoi nucleation and growth transformation: Results for one and three dimensions

     Pineda Soler, Eloy; Crespo, D
    Physical review E: statistical, nonlinear, and soft matter physics
    Vol. 78, num. 2
    Date of publication: 2008-09
    Journal article

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

     Bruna Escuer, Pere; Crespo Artiaga, Daniel; 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
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  • Short-range order of Cr and Mo in amorphous steels by EXAFS

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

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  • Structural characterization of Fe-based BMGs by Mössbauer spectroscopy

     Pineda Soler, Eloy; Facchini, L; Bruna Escuer, Pere; Serrano, J.; Crespo Artiaga, Daniel
    The 13th International Conference on Rapidly Quenched & Metastable Materials
    Presentation of work at congresses

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

     Pineda Soler, Eloy; Serrano Gutierrez, Jorge; Bruna Escuer, Pere; Crespo Artiaga, Daniel; Pradell Cara, Trinitat
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  • Vibrational density of states of Pd-based metallic glasses

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

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  • Temperature dependence study of high-frequency dynamics of fragile metallic glasses by inelastic x-ray scattering

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

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  • Determination of the most suitable container for the study of the liquid atomic structure of Mg based metallic glasses

     Serrano Gutierrez, Jorge; Bruna Escuer, Pere; Pradell Cara, Trinitat; Pineda Soler, Eloy; Crespo Artiaga, Daniel; Labrador, A.; Martínez Casado, Francisco Javier
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  • Mechanical Properties of Bulk Metallic Glasses by Inelastic X-ray Scattering

     Serrano Gutierrez, Jorge; Pineda Soler, Eloy; Bruna Escuer, Pere; Crespo Artiaga, Daniel
    13th International Conference on Rapidly Quenched & Metastable Materials RQ13
    p. 1
    Presentation of work at congresses

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  • Mechanical properties of BMG determined by Synchrotron Radiation: a microscopic picture

     Serrano, J.; Pineda Soler, Eloy; Bruna Escuer, Pere; Labrador, A; Tacon, M Le; Krisch, M; Monaco, Giulio; Crespo Artiaga, Daniel
    ISMANAM 2008 International Symposium on Metastable and Nano Materials
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  • Mechanical properties of BMG determined by Inelastic X-Ray Scattering

     Serrano, J.; Pineda Soler, Eloy; Bruna Escuer, Pere; Labrador, A; Tacon, M Le; Zhao, K; Krisch, M; Monaco, Giulio; Crespo Artiaga, Daniel
    NOCLAMS 2008 New opportunities and challenges for liquid and amorphous materials science
    Presentation of work at congresses

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