The effect of solute atoms on the bulk and grain boundary cohesion in Ni: Implications for hydrogen embrittlement

Solute atoms dissolved in the Ni matrix can segregate to grain boundaries and have a pronounced effect on the performance of Ni-base alloys. Some elements, like, hydrogen lead to deterioration of interatomic bonding in the alloys resulting in a phenomenon known as hydrogen embrittlement. In this paper, we investigate the effect of 83 impurity atoms on the bulk and grain boundary decohesion resistance of Ni by calculating changes in the partial cohesive energy and in the grain boundary work of separation from density functional theory. The calculated results are used as training sets for two machine learning models. Both models are based on the use of the partial cohesive energies as one of the key features and posses very good predictive capability. The calculated data are analyzed in detail to identify the effect of all computed solutes on the grain boundary cohesive properties in Ni general and their effect on the overall resistance of Ni to hydrogen enhanced decohesion in particular.