Embracing the chaos: Alloying adds stochasticity to twin embryo growth

TL;DR

This paper investigates how solute atoms influence twin embryo growth in Mg-Al alloys, revealing a stochastic incubation stage affected by Al composition and a subsequent deterministic growth stage, with implications for alloy microstructure control.

Contribution

It introduces a detailed atomistic understanding of twin variant selection, highlighting the role of solute-induced stochasticity and pinning effects in Mg-Al alloys.

Findings

Higher Al promotes stochastic twin embryo incubation.

Disconnection pinning leads to multiple twin variants.

Stochastic and deterministic stages govern twin growth.

Abstract

High-throughput atomistic simulations reveal the unique effect of solute atoms on twin variant selection in Mg-Al alloys. Twin embryos first undergo a stochastic incubation stage when embryos choose which twin variant to adopt, and then a deterministic growth stage when embryos expand without changing the selected twin variant. An increase in Al composition promotes the stochastic incubation behavior on the atomic level due to nucleation and pinning of interfacial disconnections. At compositions above a critical value, disconnection pinning results in multiple twin variant selection.