Solute effects on interfacial dislocation emission in nanomaterials: nucleation site competition and neutralization

TL;DR

This paper investigates how solute additions influence interfacial dislocation emission in nanomaterials, revealing complex effects due to segregation site competition and clustering that can optimize or weaken material strength.

Contribution

It demonstrates the complex interplay of solute segregation and clustering at interfaces, affecting dislocation emission and material strength in nano-crystalline metals.

Findings

Solute segregation rates vary at different interfaces.

Cluster formation near grain boundaries introduces new dislocation sources.

Material strength peaks at an optimal solute concentration.

Abstract

Interfacial nucleation is the dominant process of dislocation generation during the plastic deformation of nano-crystalline materials. Solute additions intended to stabilize nano-crystalline metals against grain growth, may segregate to the grain boundaries and triple junctions where they can affect the process of the dislocation emission. In this Letter we demonstrate that the effect of solute addition in a nano-crystalline material containing competing solute segregation sites and dislocation sources can be very complex due to different rates of segregation at different interfaces. Moreover, at large concentrations, when the solutes form clusters near the grain boundaries or triple junctions, the interfaces between these clusters and the matrix can introduce new dislocation emission sources, which can be activated under lower applied stress. Thus, the strength maximum can occur at a certain solute concentration: adding solutes beyond this optimal solute concentration can reduce the strength of the material.