Phase transition in the Zr60Al15Ni25 bulk metallic glass subjected to rolling at room temperature

The microstructure evolution of the Zr60Al15Ni25 metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns and exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees ɛ. As ɛ is not large than 20%, the values of FWHM and ΔH are lower than that of the as-cast state. When ɛ reaches 30%, the values of FWHM and ΔH become larger than that of the as-cast state, while their values begin to decrease again as ɛ reaches about 85%. These results indicate that the reversible transitions between ordered and disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering and shear-induced disordering during rolling.