Strategy for pinpointing the formation of B2 CuZr in metastable CuZr-based shape memory alloys

In the present work we systematically investigated the formation of high-temperature B2 CuZr intermetallics in 36 metastable CuZr-based alloys. The results demonstrate that a B2 CuZr solid-phase transformation exists at high temperature. Based on continuous heating transformation diagrams the CuZr-based alloys can be classified into three different types, related to the precipitation and stability of the B2 phase. A new prediction strategy for the formation of different sized CuZr-based shape memory bulk metallic glass composites (BMGC) is proposed by considering the competition between vitrification, the precipitation of metastable B2 CuZr and room-temperature equilibrium phases. These insights are condensed into a new parameter, K = Tf/TL, where Tf and TL are the final temperature of the B2 CuZr phase transformation during heating and the liquidus temperature of the alloy, respectively, which is suggested to predict and select a compositional region of different sized BMGC. This new approach could be of great significance for the development of metastable CuZr-based shape memory alloys with enhanced deformability.