Shear band formation and mechanical properties of Zr 38Ti 17Cu 10.5Co 12Be 22.5 bulk metallic glass/porous tungsten phase composite by hydrostatic extrusion

Abstract

Zr 38Ti 17Cu 10.5Co 12Be 22.5 bulk metallic glass/porous tungsten phase composites were prepared via a method by combining infiltrating the molten alloy into the reinforcement with hydrostatic extrusion. The deformation and failure behavior of the as-extruded composite were investigated at room temperature under quasistatic compression. Compared to the as-cast composite, the as-extruded composite presented greater flow stress and lower fracture strain. Different from the fracture mode of multiple macro shear bands for the as-cast composite, fractrographic analysis revealed that the specimen for the as-extruded composite fractured by a mixture of shearing and axial splitting. It is suggested that the increase in flow stress for the as-extruded composite is attributed to the extrusion process which introduced hardened condition in the tungsten phase. The fracture strain of the as-extruded composite decreased by comparison with the as-cast composite is proposed to result from the joint effects of the employed extrusion process sacrificed part of the plasticity, relatively high flow stress exceeded the fracture stress of the pure metallic glass, and the elongated grain structure resulted in splitting mode for the as-extruded composite.