Divergent Evolution of Slip Banding in Alloys

TL;DR

This paper uncovers two distinct types of slip bands in alloys, revealing different mechanisms of deformation localization at microscopic and atomic scales, advancing fundamental understanding of material deformation.

Contribution

It introduces the existence of confined and extended slip bands in alloys, with distinct formation mechanisms, challenging classical models of dislocation behavior.

Findings

Confined slip bands arise from repetitive dislocation emissions at Frank-Read sources.

Extended slip bands result from slip-induced dislocation source deactivation and new source generation.

The study provides atomic-scale insights into collective dislocation motion and deformation instability.

Abstract

Metallic materials under high stress often exhibit deformation localization, manifesting as slip banding. Over seven decades ago, Frank and Read introduced the well-known model of dislocation multiplication at a source, explaining slip band formation. Here, we reveal two distinct types of slip bands (confined and extended) in alloys through multi-scale testing and modeling from microscopic to atomic scales. The confined slip band, characterized by a thin glide zone, arises from the conventional process of repetitive full dislocation emissions at Frank-Read source. Contrary to the classical model, the extended band stems from slip-induced deactivation of dislocation sources, followed by consequent generation of new sources on adjacent planes, leading to rapid band thickening. Our findings provide critical insights into atomic-scale collective dislocation motion and microscopic deformation instability in advanced structural materials, marking a pivotal advancement in our fundamental understanding of deformation dynamics.