Phase field crystal modeling of early stage precipitation and clustering

TL;DR

This paper employs a phase field crystal model to study early-stage precipitation and clustering in dilute alloys, revealing how quenched-in defects influence cluster formation and growth.

Contribution

It introduces a phase field crystal approach to analyze the impact of dislocations on nucleation and growth of clusters, extending understanding beyond molecular dynamics timescales.

Findings

Dislocations lower the energy barrier for nucleation.

Stress relaxation promotes cluster growth.

Highly strained regions facilitate first-order transitions.

Abstract

A phase field crystal model is used to investigate the mechanisms of formation and growth of early clusters in quenched/aged dilute binary alloys, a phenomenon typically outside the scope of molecular dynamics time scales. We show that formation of early sub-critical clusters is triggered by the stress relaxation effect of quenched-in defects, such as dislocations, on the energy barrier and the critical size for nucleation. In particular, through analysis of system energetics, we demonstrate that the growth of sub-critical clusters into overcritical sizes occurs due to the fact that highly strained areas in the lattice locally reduce or even eliminate the free energy barrier for a first-order transition.