Nucleation Kinetics in Al-Sm Metallic Glasses

TL;DR

This study uses molecular dynamics simulations to analyze how samarium affects the nucleation process in aluminum-based metallic glasses, revealing that Sm suppresses nucleation by increasing attachment barriers.

Contribution

It provides new insights into the nucleation kinetics in Al-Sm metallic glasses, specifically quantifying how Sm concentration influences delay times and critical cooling rates.

Findings

Delay time increases exponentially with Sm concentration

Critical cooling rate decreases exponentially with Sm concentration

Sm suppresses Al nucleation by increasing attachment barriers

Abstract

The isothermal nucleation kinetics in Al-Sm metallic glasses with low Sm concentrations (xSm) was studied using molecular dynamics simulations in order to calculate time-temperature-transformation curves. The average delay time of Al nanocrystal nucleation was found to increase exponentially with xSm, whereas the estimated critical cooling rate necessary to avoid crystallization decreases exponentially with xSm. Sm solutes were found to suppress Al nucleation by increasing the attachment barrier and therefore by reducing the attachment frequency. The analysis shows that the attachment of Al to the evolving nucleus has the same characteristics as Al diffusion within the amorphous matrix and they both take place heterogeneously via collective movement of a group of Al atoms.