Molecular dynamics simulation of gradient alloying distribution on the nano-mechanical properties of Nb-Zr alloys

Abstract In this work, a nano-indentation process of homogeneous Nb-Zr alloy and gradient Nb-Zr alloy was simulated using molecular dynamics simulation. The effects of indentation radius, Zr content and system temperature on the mechanical properties and micro-deformation were investigated. The influence of indentation size on nano-indentation experiments was mainly affected by the curvature of the indented part. Comparing the homogeneous and gradient alloys, it was revealed that the gradient alloy had a smoother mechanical performance. The results showed that the effect of Zr content on the hardness of Nb-Zr homogeneous alloy was not linear. The hardness rose, followed by a decline with increasing Zr content, and the turning point came at 1.5 wt%. Under high temperatures, the Nb-Zr homogeneous alloy and gradient alloy layer retained extremely high hardness, exhibiting excellent mechanical properties. Due to the entanglement of multiple dislocations in gradient Nb-Zr alloy at high temperatures, the hardness still increased with increasing temperature at high temperatures. It was worth noting that gradient alloys could disperse stress faster and reach a stable state during the loading process. The hardness of the Nb-Zr homogeneous alloy layer first increased and then decreased as the Zr content changed from 1.0 wt% to 2.0 wt%, as verified by the experiments. This study provided the reference for the preparation of high-temperature applications alloy by constructing Nb-Zr gradient alloy.