Structure of the glass-forming metallic liquids by ab-initio and classical molecular dynamics, a case study: quenching the Cu60Ti20Zr20 alloy

TL;DR

This study compares ab-initio and classical molecular dynamics simulations to understand the amorphization process of Cu60Ti20Zr20 metallic alloy, highlighting the importance of liquid structure parametrization for accurate predictions.

Contribution

It introduces a new parametrization approach based on liquid structure for semi-empirical potentials, improving the transferability and accuracy of amorphous structure predictions.

Findings

Liquid structure prediction aligns well with experiments when parametrized on liquid data.

The final amorphous structure closely matches ab-initio results and X-ray diffraction data.

Parametrization on liquid structure enhances the transferability of potentials across different states.

Abstract

We consider the question of the amorphization of metallic alloys by melt quenching, as predicted by molecular dynamics simulations with semi-empirical potentials. The parametrization of the potentials is discussed on the example of the ternary Cu-Ti-Zr transition metals alloy, using as reference the ab-initio simulation. The pair structure in the amorphous state is computed from a potential of the Stillinger Weber form. The transferability of the parameters during the quench is investigated using two parametrizations: from solid state data, as usual, and from a new parametrization on the liquid structure. When the adjustment is made on the pair structure of the liquid, a satisfactory transferability is found between the pure components and their alloys. The liquid structure predicted in this way agrees well with experiment, in contrast with the one obtained using the adjustment on the solid. The final structure, after quenches down to the amorphous state, determined with the new set of parameters is shown to be very close to the ab-initio one, the latter being in excellent agreement with recent X-rays diffraction experiments. The corresponding critical temperature of the glass transition is estimated from the behavior of the heat capacity. Discussion of the consistency between the structures predicted using semi-empirical potentials and ab-initio simulation, and comparison of different experimental data underlines the question of the dependence of the final structure on the thermodynamic path followed to reach the amorphous state.