Phase formation and mechanical properties of Cu-Zr-Ti bulk metallic glass composites

Abstract

The effect of the type of the crystalline phase and its volume fraction on the mechanical property of Cu₅₀Zr_50-xTi_x alloys (x = 0-10) bulk metallic glass composites has been investigated in this study. Up to 6 at% of Ti, B19’ phase particles distributed in the glassy matrix, while at 8 and 10% of Ti, B2 phase particles are retained in the glass matrix due to suppression of the eutectoid transformation of B2 phase and by avoidance of martensitic transformation of B2 into B19’. The volume fraction of crystalline phase is strongly dependent on the cooling rate. The larger volume fraction of the crystalline phases results in the lower yield stress, the higher plastic strain, and the more pronounced work hardening behavior. At the crystalline volume fraction below ~30%, the variation of the yield strength can be described by the rule of mixture model (ROM), while at the crystalline volume fraction higher than ~50% by the load-bearing model (LBM). At the crystal fractions between 30 and 50%, there is a yield strength drop and a transition from the ROM to the LBM. This transition is due to the formation of the crystalline structural framework at higher crystal fraction.