Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-“double”-to-“triple”-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.