Shear localization of nanoscale W in metallic glass composites

Abstract

High-density tungsten/metallic glass composites were fabricated by warm extrusion of two different powders. The first powder was a physical blend of −45 μm tungsten and Hf-based metallic glass powders and produced a relatively coarse distribution of tungsten particles within a continuous metallic glass matrix. The second powder was synthesized by mechanical milling the −45 μm tungsten and Hf-based metallic glass powders into composite particles composed of 20–500-nm layers of tungsten and metallic glass. The amorphous structure of the starting glass powders did not change during milling. Some macroscopic plasticity during compression testing was observed due to the formation of multiple shear bands at the interface between the coarse tungsten particles and the metallic glass matrix in the composite produced from blended powders. In contrast, shear localization without a decrease in strength occurred uniformly throughout the nano-grained tungsten and metallic glass phases in the sample obtained from extruded composite powders.