Improving the plasticity of bulk metallic glasses via pre-compression below the yield stress

The poor plasticity of bulk metallic glasses (BMGs) has severely limited their potential structural applications. In this paper, we reported that uniaxial pre-compression below the yield stress can be used to significantly improve the plasticity of BMGs. An as-cast Cu36Zr48Al8Ag8 BMG was pre-compressed under various pressures (400, 800 and 1600 MPa) and durations (30, 60 and 120 min). The pre-compression processes led to structural change that increases the free volume and produces nanocrystals in the BMG matrix, which subsequently improved the plasticity of the BMG. Detailed data analysis showed that increasing the applied pressure speeds up the structural relaxation process and nanocrystallization occurs only at high enough pressure. This investigation indicated that appropriate selection of the pressure and duration of a pre-compression process is critical for the improved plasticity of BMGs.