HPDC Forming and Mechanical Properties of Stainless-Steel Skeleton Reinforced Zr-Based Bulk Metallic Glass Composites

304 stainless steel skeletons were introduced into Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) bulk metallic glasses (BMGs) by high pressure die casting (HPDC) technique under high pressure and with large filling rate to create BMG/stainless steel composites. Furthermore, the effects of stainless-steel volume fraction on the microstructure and mechanical properties were studied. The results show that the stainless steel skeleton in the HPDCed composites is uniformly distributed in the metallic glassy matrix and displays metallurgical interface with the Vit1 BMG. The mechanical properties test indicates that the plasticity of the brittle Vit1 BMG is significantly improved with the introduction of stainless steel skeleton. As the mesh number of stainless steel increases ( corresponding to the increase of the volume fraction of crystalline phase), the plasticity of composites displays an increasing trend. However, when the mesh number exceeds 200, there are some deteriorations in mechanical properties due to the unfilled porosity defects in the composites. When the volume fraction of crystalline phase is about 53.7%, the fracture strain of composites reaches the maximum value of about 10%, which is much higher than that of Zr-based BMG composites toughened by traditional stainless steel fibers. The analysis of the toughening mechanism shows that the brittle-ductility transition of the HPDCed Vit1 BMGs mainly results from high efficiency suppression of shear band propagation by metal skeleton, which promotes the proliferation and initiation of shear bands and reduces the localization of macroscopic plastic deformation, as well as the reduced stress concentration due to decrease of mesh number. This study provides new insights for the design and preparation of BMGs composites with excellent mechanical properties, and has important engineering value for application of BMGs.