Strengthening Materials by Engineering Coherent Internal Boundaries at the Nanoscale

TLDR

Traditional strengthening relies on creating internal defects that impede dislocation motion but typically reduces ductility. The study proposes a method to enhance strength and ductility by engineering coherent, nanoscale twin boundaries with high stability and sub‑100‑nm features, and discusses broader applications. The authors develop a methodology that identifies and engineers coherent, thermally and mechanically stable twin boundaries smaller than 100 nm to improve strength and ductility.

Abstract

Strengthening materials traditionally involves the controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Such strategies invariably compromise ductility, the ability of the material to deform, stretch, or change shape permanently without breaking. Here, we outline an approach to optimize strength and ductility by identifying three essential structural characteristics for boundaries: coherency with surrounding matrix, thermal and mechanical stability, and smallest feature size finer than 100 nanometers. We assess current understanding of strengthening and propose a methodology for engineering coherent, nanoscale internal boundaries, specifically those involving nanoscale twin boundaries. Additionally, we discuss perspectives on strengthening and preserving ductility, along with potential applications for improving failure tolerance, electrical conductivity, and resistance to electromigration.