The synthesis and properties of Zr-based metallic glasses and glass-matrix composites

Abstract

In this article, the formation of metallic glass composites in the system Zr/Ti-Al-Cu-Ni by partial devitrification or by blending with second-phase particles through solid-state processing is discussed with respect to the effect of second phases on the thermal stability of the glassy matrix and on mechanical properties. The composites exhibit no significant reduction of the supercooled liquid region as compared to the particle-free metallic glass. The viscosity of the supercooled liquid increases with an increasing volume fraction of particles. The mechanical behavior was characterized by microhardness measurements and constant compression rate tests. At room temperature, there is a significant increase in yield strength with an increasing volume fraction of crystalline phases. At temperatures around the glass transition, the influence of these nanoscaled particles is of minor importance. Rather, the homogeneous flow of the composites is determined by Newtonian viscous flow of the amorphous matrix. This opens a promising route for easy shaping of complex parts of bulk metallic glasses at temperatures that are above T_g.