Stress-induced martensitic transformations in CuZrAl bulk metallic glass forming alloys

In this paper, 5 mm diameter Cu46.5Zr48.5Al5 bulk metallic glass forming alloys were prepared by water cooled Cu-mould cast. Microstructural observation shows that the alloys consist of amorphous phase and crystalline phase containing CuZr martensite. The deformation behaviors of the crystalline region and amorphous phase in the alloys were studied by means of nanoindentation tests under progressive multicycle mode. The results reveal that the unloading and the subsequent reloading h–p curves for the amorphous phase can retrace each other. While for the crystalline region, an obvious hysteresis loop was found between the unloading and reloading h–p curves in the typically elastic regime, indicating the occurrence of ‘stress-induced phase transformation’. This unique deformation behavior of the material was also confirmed by using uniaxial compression tests.