Influence of Defects to Zr65Cu18Ni7Al10 Bulk Metallic Glass Properties Under Dynamic Compression

The Zr65Cu18Ni7Al10 bulk metallic glass with smaller diameter exhibits higher fracture strength under dynamic compression, which is ascribed to concentration of flow defect. The density of shear bands in the sample surface will increase with decreasing of the diameter, whereas, average distance and width of tear ridges in the fracture surface will increase with larger diameter. In addition, the volume of shear transformation zone can be estimated, which presents a ductile-to-brittle transition with the change of diameter. The physical graph of shear transformation zone can be obtained from the experimental analysis.

Molecular Dynamics Study of the Nanoindentation Behavior of Cu64Zr36/Cu Amorphous/Crystalline Nanolaminate Composites

Amorphous/crystalline nanolaminate composites have aroused extensive research interest because of their high strength and good plasticity. In this paper, the nanoindentation behavior of Cu64Zr36/Cu amorphous/crystalline nanolaminates (ACNLs) is investigated by molecular dynamics (MD) simulation while giving special attention to the plastic processes occurring at the interface. The load–displacement curves of ACNLs reveal small fluctuations associated with shear transformation zone (STZ) activation in the amorphous layer, whereas larger fluctuations associated with dislocations emission occur in the crystalline layer. During loading, local STZ activation occurs and the number of STZs increases as the indentation depth in the amorphous layer increases. These STZs are mostly located around the indenter, which correlates to the high stresses concentrated around the indenter. When the indenter penetrates the crystalline layer, dislocations emit from the interface of amorphous/crystalline, and their number increases with increasing indentation depth. During unloading, the overall number of STZs and dislocations decreases, while other new STZs and dislocations become activated. These results are discussed in terms of stress distribution, residual stresses, indentation rate and indenter radius.