Effect of medium-range ordered nanoclusters on compression deformation of Mg65Cu25Y10 metallic glasses

Abstract

Establishing the relationship between microstructures and mechanical properties of metallic glasses (MGs) is of great significance for guiding its application. Therefore, four groups of Mg65Cu25Y10 MGs with the same size were obtained by rapid solidification at four pressures by molecular dynamics (MD) simulation in this paper, and uniaxial compression were performed. The results show that the volumes of shear transformation zones (STZ) of four models increase sequentially. The average atomic potential energy increases, and the plasticity increases. The smaller the non-affine displacement (NAD), the higher Top-10 Topologically close-packed (TCP) and defective TCP clusters, which are the main structural units of MGs. Medium-range ordered (MRO) nanoclusters composed of their interconnections, are broken into small-sized nanoclusters during compression. Regions with large-sized MRO nanoclusters tend to be "stiffer", making these regions difficult for large-scale structural rearrangement and plastic flow. The deformation resistance of these regions is thus improved. Chain-like nanoclusters are easier broken during compression, and MRO nanoclusters linked with larger bond numbers can withstand greater strain for enhancing their plasticity. These findings have excellent theoretical guidance for promoting plasticity in MGs.