arXiv subjects

Rene Alvarez-Donado

Publications and source records attributed to Rene Alvarez-Donado.

3 recordsLinked to original sources

arXiv2026

Transmutation-accelerated sampling method for multi-component ZrCu(Al) metallic glasses

We investigate multi-component metallic glass systems using a hybrid Molecular Dynamics (MD) and Variance-Constrained Semi-Grand Canonical approach. This method enables us to generate samples with properties consistent with experimental observations, at deeply supercooled states that are typically inaccessible with conventional MD simulations. Using a realistic interatomic potential, we investigate the dynamics, kinetic stability, and rheology of a ZrCu(Al) metallic glass, together with the widely studied ZrCu system, in the low-temperature glassy regime. Our results demonstrate how the hybrid method enhances relaxation and provides a generic framework for modeling realistic complex metallic glasses.

cond-mat.dis-nn↗

arXiv2025

Composition effect in the thermo-mechanical behavior of glasses, and its modelization

We employed molecular dynamics simulations to explore comparatively the thermo-mechanical behavior of two glass materials-an oxide silica glass (SiO2) and a binary Cu-Zr-based metallic alloy (Cu50Zr50)-during shear and elongation deformation cycles. By calculating the energy balance and tracking the temperature evolution of both glasses under deformation cycles, we are able to propose, for each of them, a constitutive law which accurately reproduces the self-heating process due to plastic deformation. These relatively simple constitutive laws involve strain rate sensitivity and a non-linear temperature dependence of the thermal dilatancy coefficients, as well as strain gradient plasticity. To identify the right parameters, both glasses are equilibrated at very low temperature (10 K) and two independent deformation rates were applied to each sample for each type of deformation. Thermal attenuation is greatly amplified in silica compared to the metallic glass. Moreover, using precise atomic description of the instantaneous deformation, combined with exact coarse-graining procedure, we show, in silica, that self-heating is mainly supported by inhomogeneous strain gradient plasticity with nanometric characteristic lengthscales.

cond-mat.mtrl-sci↗

arXiv2023

Quasi-localized modes in crystalline high entropy alloys

High Entropy Alloys (HEAs) are designed by mixing multiple metallic species in nearly the same amount to obtain crystalline or amorphous materials with exceptional mechanical properties. Here we use molecular dynamics simulations to investigate the role of positional and compositional disorder in determining the low-frequency vibrational properties of CrMnFeCoNi HEAs. Our results show that the expected dependence of the density of states on the frequency as $D(ω)\simω^4$ is recovered for amorphous HEAs and is also observed for partially crystallized alloys with deviations that depend on the degree of crystallization. We find that the quasi-localized vibrations are still visible in crystalline HEAs, albeit suppressed compared to the corresponding amorphous alloys. Our work offers a unified perspective to describe HEA mechanical properties in terms of their vibrational density of states.

cond-mat.dis-nn↗