Devitrification process in rapidly solidified Al-Ni-Cu-Nd metallic glass

Abstract

In the present study, rapidly solidified ribbons of Al87Ni7Cu3 Nd3 metallic glass was prepared by using melt spinning. Devitrification process of the totally amorphous ribbons was investigated by high temperature X-ray diffraction analysis, combining with differential scanning calorimetry, under continuous and isothermal heating regime. The X-ray diffraction intensity and full width at the half maximum (FWHM) were analyzed to investigate the increase of crystallized amount and growth of α-Al crystal particles. The results show that under continuous heating regime, the metallic glass devitrifies via two main stages: primary crystallization, resulting in two-phase mixture of α-Al plus residual amorphous phase, and secondary crystallization, corresponding to rapid precipitation of some inter-metallic phases in the form of dispersion or eutectic mixture. Under isothermal heating regime, only Al crystal precipitates from the Al-rich amorphous matrix at low temperature, and when heating at 280 °C only Al crystal precipitates within a short time, and then Al8Cu4Nd forms, followed by Al3Ni, in the residual amorphous phase. When heating at higher temperature or for longer time, Al11Nd3 forms, the amorphous phase disappears, and the ribbons develop into polycrystalline morphologies with multiply phase mixture of α-Al, Al8Cu4Nd, Al3Ni, and Al11Nd3.