Molecular Dynamics Computer Simulation of Crystal Growth and Melting in Al50Ni50

TL;DR

This study uses molecular dynamics simulations to analyze the melting and crystallization of Al50Ni50, providing insights into interface velocities, melting temperature, and growth kinetics, highlighting limitations of classical models.

Contribution

It offers a detailed molecular dynamics analysis of Al50Ni50 crystal growth and melting, including a new estimate of the kinetic growth coefficient and critique of classical models.

Findings

Melting temperature accurately estimated from interface velocity.

Kinetic growth coefficient found to be 0.0025 m/s/K.

Classical Wilson-Frenkel model does not quantitatively describe growth kinetics.

Abstract

The melting and crystallization of Al50Ni50} are studied by means of molecular dynamics computer simulations, using a potential of the embedded atom type to model the interactions between the particles. Systems in a slab geometry are simulated where the B2 phase of AlNi in the middle of an elongated simulation box is separated by two planar interfaces from the liquid phase, thereby considering the (100) crystal orientation. By determining the temperature dependence of the interface velocity, an accurate estimate of the melting temperature is provided. The value k=0.0025 m/s/K for the kinetic growth coefficient is found. This value is about two orders of magnitude smaller than that found in recent simulation studies of one-component metals. The classical Wilson-Frenkel model is not able to describe the crystal growth kinetics on a quantitative level. We argue that this is due to the neglect of diffusion processes in the liquid-crystal interface.