Effect of Cr Segregation on Mechanical Behavior and Deformation Mechanism of Ni─Co─Cr Alloy

Abstract

Ni─Co alloys have attracted extensive attention from materials researchers in recent years because of their excellent properties. The effect of solute segregation on the properties of the alloy is studied by molecular dynamics simulation. The results show that the yield strength increases from 2.8 to 3.5 GPa when the solute atom Cr is introduced into the grain boundary. Under the action of stress, the disorder of segregation grain boundary is enhanced, which hinders the growth of grain, produces less layer fault structure, and the peak number of HCP (Hexagonal Close Packed) atom decreases from 50 000 to 37 000. The introduction of solute atoms provides a strong support for the grain boundary and has a similar skeleton structure, which improves the deformation resistance of the lattice. In addition, the improved grain boundary stability leads to the difficulty of nucleation of the dislocation, because the obstruction of the grain boundary makes it difficult to activate the dislocation source in the adjacent grain, and the maximum reduction of the perfect dislocation is 74%. In general, the microscopic mechanism of solute segregation strengthening is discussed from dislocation, phase structure, and energy, which provides guidance for plastic deformation of solid-solution alloys.