Effect of atomic order/disorder on Cr segregation in Ni-Fe alloys

Recent irradiation experiments on concentrated random solid solution alloys (CSAs) show that some CSAs can undergo disorder-to-order transition, i.e., the atoms that are initially randomly distributed on a face centered cubic crystal lattice undergo ordering (e.g., L1(0) or L1(2)) due to irradiation. In this work, we elucidate that the atomic structure could affect the segregation properties of grain boundaries. While working on Ni and Ni-Fe alloys, from static atomistic simulations on 138 grain boundaries, we show that despite identical alloy composition, Cr segregation is higher in the disordered structures compared to ordered structures in both Ni0.50Fe0.50 and Ni0.75Fe0.25 systems. We also show that grain boundary (GB) energy could act as a descriptor for impurity segregation. We illustrate that there is a direct correlation between Cr segregation and grain boundary energy, i.e., segregation increases with the increase in the GB energy. Such correlation is observed in pure Ni and in the Ni-Fe alloys studied in this work. Published by AIP Publishing.