The sulfur embrittlement in Ni-Al-Re model single crystal alloys: Sulfur-induced precipitation of Rhenium-rich δ phase

Abstract

The impurity sulfur embrittlement of Ni-based single alloys has long been wrapped in mystery. In this work, we report for the first time the sulfur-induced precipitation of brittle rhenium-rich δ phase in a model Ni-based single alloy. The results showed that the addition of sulfur gave rise to the precipitation of rhenium-rich δ phase with hexagonal close-packed (HCP) crystal structure in the dendritic cores. Besides, the enrichment of sulfur and nickel elements were detected in the δ phase. The behavior of sulfur-induced precipitation of δ phase was rationalized by the first-principles calculations, which indicates that there is a strong bonding interaction between sulfur and rhenium atoms. This work provides a novel perspective on the understanding of the sulfur embrittlement in Ni-based single alloys.