Effects of segregation on grain-boundary cohesion: A density-functional cluster model of boron and sulfur in nickel

Abstract

Impurity-dopant effects on grain-boundary cohesion have been studied in a first-principles local spin-density atomic-cluster model of octahedral hole sites in nickel. Rigorous calculations of the total energy and gradient forces on the host atoms show that boron (an enhancer of cohesion) increases the maximum sustainable restoring force in the cluster, and sulfur (an embrittler) decreases the value of this force, consistent with observed segregation behaviors of these atoms.