The Influence of High-Pressure Torsion on the Free Volume and Shear-Band Formation during the Indentation of Vit105 Metallic Glass

Abstract

The research on structural features, microhardness distribution, and deformation features of Vit105 bulk metallic glass (BMG) before and after high-pressure torsion (HPT), as well as after relaxing annealing, has been carried out. HPT n = 1 leads to an increase in free volume ΔV, and relaxing annealing leads to a decrease in ΔV and non-uniformity relative to the initial state of BMG. In the initial BMG and in the BMG after relaxing annealing, microhardness is uniformly distributed over the surface, while in the material subjected to HPT, the microhardness distribution is more heterogeneous. The bonded-interface indentation of the BMG has been conducted in different states. The formation of numerous concentric bands around the indenter is observed. The pattern of band distribution is more homogenous in Vit105 BMG alloy before HPT. In relaxed samples, the bands often have fractures and irregularities, as well as cracks that can be seen under the indents. After HPT, the formation of several intensity bands can be observed, as well as a number of low-intensity ones between the main intensity bands. The average distance between the bands in the initial BMG and BMG after HPT is close to identical, while the distance between the bands is smaller in the relaxed state, which reflects the lower plasticity of the material after annealing.