Evolution Of Distribution And Density Of Shear Bands In Compression Deformation Of Cu₄₅Zr₄₆Al₇Ti₂Bulk Metallic Glass

Metallic glasses, also known as amorphous alloy, are prepared by rapidly quenching from the liquid alloy. Unlike traditional crystal materials, metallic glasses generally have high strength, high hardness, high elastic limit and high corrosion resistance and have become a new kind of materials with great prospect However, most of metallic glasses are brittle at room temperature, which restricts their wide applications. The plastic deformation of metallic glass is inhomogeneous at temperatures below the glass transition temperature and high stress and are highly localized in thin regions called shear bands. Once shear bands formed, they can easily extend to cracks which can lead to brittle fracture of materials. Branches and intersection behavior can effectively hinder the extension of primary shear bands under conpressive loading. So, metallic glasses generally display plasticity under compressive loading. Therefore, the analysis of the distribution of shear bands in metallic glasses under compressive lording can help us to understand the mechanism of inhomogeneous plastic deformation in metallic glass. Furthermore, shear bands in metallic glasses have lower atomic density and enhanced free volume relative to undeformed region. A high density of shear bands in metallic glass will affect the structure and properties. Therefore, attempt to produce a high density of shear bands in metallic glasses can also provide some ideas for the development of new materials.This paper based on compression deformation of the Cu45Zr46Al4Ti2bulk metallic glass. The evolution of distribution and density of shear bands with strain, strain rate and aspect rate has been studied. The condition of high-density shear bands has been optimized. Meanwhile, the structure change of the deformed metallic glass has been also analyzed.The results show that the density of shear bands increases with stain. The increase in the density of shear bands is more significant for strains larger than56%. The distribution of shear bands will be more localized with increasing aspect ratio, shear bands density increases at the same time. Shear bands are homogeneously distributed in small-sized or triangular-shaped samples. This metallic glass has maintained amorphous structure and did not crystallize during compression deformation.Shear bands with spacings less than100nm widely exist in the sample by compression deformation. But most fine-spaced shear bands exist only in local areas and teir proportion in overall number of shear bands can reach10.99%. The smallest average spacing of shear bands is667nm, far less than the data reported in most of literatures.