Temperature-dependent evolution of strength of nanocrystalline Ni(Mo) alloys at the Mo solubility limit

Abstract

This study aims to understand the thermal stability and annealing hardening behavior of nanocrystalline Ni(Mo) alloys at the Mo solubility limit. The microstructural and microhardness evolution of these alloys is investigated at different annealing temperatures. A rather stagnant grain growth, along with the gradual crystallization of amorphous nanostructures, in the Ni(Mo) alloys has been observed at high temperatures. The Ni(Mo) alloys with Mo content above the solubility limit exhibit an abnormal secondary hardening behavior at high temperatures, accompanied by nanosized MoNi precipitates. It demonstrates that the residual amorphous nanostructures play an important role in the thermal stability of nanocrystalline alloys. It also implies that the addition of the solute up to a solubility limit in the nanocrystalline alloys can help achieve superior strength at high temperatures.