Segregation of Solutes at Dislocations: A New Alloy Design Parameter for Advanced Superalloys

Abstract

The interactions of solutes with crystal defects at near-atomic-level were investigated in five single-crystal nickel-based superalloys deformed at temperatures between 850 and 1160 °C and various deformation conditions. These interactions, and consequently the composition of a particular solute that segregates at a crystal defect, are controlled by the type of the crystal defect, the deformation conditions, i.e., temperature and stress, and the overall alloy composition. Atomistic phase-field simulations also reveal the effect of dislocation velocity on the amount of solutes that can segregate on dislocations. The observed plasticity-assisted redistribution of interacting solutes phenomena results in microstructural and chemical alterations, which are associated with recrystallization, rafting, and the formation of topologically close-packed phases. Deciphering these interactions by enabling quantitative three-dimensional imaging of solutes at crystal defects with high sensitivity and spatial resolution will allow to develop a solute–defect database that can be used as a key-design parameter for advanced superalloys.