Effect of Intragranular Solute Atom Segregation on the Mechanical Properties of the Ni–Co Alloy

Abstract

In the present contribution, a certain amount of Co atoms was added to the grains (GI) of nano-polycrystalline Ni by a molecular dynamics method to study the effect of solute atom content on the mechanical properties of the alloy. It was found that the tensile strength and yield strength of the alloy increased with the increase of Co atomic content. With the increase of Co content, the grain boundary atomic potential energy decreased and the grain boundary became more stable. As the strain increased, the Co atoms in the grain migrated to the grain boundary, the lattice distortion at the grain boundary increased, and the dislocation nucleation at the grain boundary increased, forming a stable dislocation network and hindering the grain boundary migration. The 1/6⟨112⟩ Shockley incomplete dislocation formed at the grain boundary became the stacking fault source, which was also the source of transformation from the internal stacking fault to the external stacking fault, finally transforming into deformation twins. As the strain increased, the content of Shockley incomplete dislocations in the crystal increased, interacting with other dislocations to dominate the deformation process.