First-principles Study of Hydrogen-induced Embrittlement in Fe Grain Boundary with Cr Segregation

Abstract

First-principles tensile tests were performed to investigate the effect of Cr segregation on the hydrogen-induced embrittlement in Fe grain boundaries. The Fe grain boundary with H and Cr segregation exhibited the higher maximum stress and strain to failure than those of the Fe grain boundary with only H segregation. Cr segregation suppressed the extension of the Fe-Fe bond weakened by H segregation. In the Fe grain boundary with H and Cr segregation, the decrease in the charge density in the bond with straining was suppressed because of charge transfer from the Cr atom to its neighboring Fe atoms. This charge accumulation in the grain boundary region is responsible for the reinforcement of bonds in the Fe grain boundary with H segregation, contributing to the suppression the hydrogen-induced embrittlement of Fe grain boundaries.