Unveiling deformation twin nucleation and growth mechanisms in BCC transition metals and alloys

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

8 Scopus Citations
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Detail(s)

Original languageEnglish
Pages (from-to)90-99
Journal / PublicationMaterials Today
Volume65
Online published17 Apr 2023
Publication statusPublished - May 2023

Abstract

Twinning provides critical stress-relieving and flaw tolerance in body-centred cubic (BCC) transition metals (TMs) when dislocation plasticity is suppressed. Twin nucleation and growth mechanisms have been studied for over half a century without a consensus. Here, we use a reduced-constraint slip method to unveil the path to twin nucleation, growth and associated energy barriers in the entire BCC TM family. Twinning is surprisingly but essentially controlled by a normalized energy difference η between the hexagonal close-packed (HCP) and BCC structures in elemental TMs, and can be effectively tuned and quantitatively predicted by first-principles calculations in TM alloys. Fracture mechanics theory with η-based barriers enables predictions of critical solute concentrations to activate twinning and reverse ductile-to-brittle transitions in BCC TMs, as demonstrated in WRe alloys. The computational approach provides a unified and quantitative method to predict twinning and a practical tool for rapid screening of alloy compositions ensuring ductile behaviour. © 2023 Elsevier Ltd.

Research Area(s)

  • BCC transition metals, Deformation twinning, Density-functional theory calculations, Ductile to brittle transition, Nucleation and growth