Interstitial segregation has the potential to mitigate liquid metal embrittlement in iron

TL;DR

This study explores how boron segregation can counteract zinc-induced embrittlement in iron grain boundaries, revealing mechanisms that could help prevent catastrophic material failure.

Contribution

It uncovers how interstitial boron mitigates zinc-induced embrittlement in iron grain boundaries through ab-initio simulations, offering new insights for material design.

Findings

Boron hinders zinc segregation at grain boundaries.

Boron compensates for zinc-induced loss in cohesion.

Interstitial solutes can modify grain boundary properties.

Abstract

The embrittlement of metallic alloys by liquid metals leads to catastrophic material failure and severely impacts their structural integrity. The weakening of grain boundaries by the ingress of liquid metal and preceding segregation in the solid are thought to promote early fracture. However, the potential of balancing between the segregation of cohesion-enhancing interstitial solutes and embrittling elements inducing grain boundary decohesion is not understood. Here, we unveil the mechanisms of how boron segregation mitigates the detrimental effects of the prime embrittler, zinc, in a $\Sigma 5\,[0\,0\,1]$ tilt grain boundary in $\alpha-$Fe ($4~at.\%$ Al). Zinc forms nanoscale segregation patterns inducing structurally and compositionally complex grain boundary states. Ab-initio simulations reveal that boron hinders zinc segregation and compensates for the zinc induced loss in grain boundary cohesion. Our work sheds new light on how interstitial solutes intimately modify grain boundaries, thereby opening pathways to use them as dopants for preventing disastrous material failure.