Elucidating the nature of crystallization kinetics in Zr46Cu46Al8 metallic glass through simultaneous WAXS/SAXS measurements

Simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) measurements were performed to investigate the low-temperature crystallization kinetics of Zr46Cu46Al8 bulk metallic glass during isothermal annealing. Quantitative analysis of the WAXS intensity data indicated that the crystallization process was dominated by steady-state homogeneous nucleation and three-dimensional diffusion-controlled growth. This observation was corroborated by quantitative analysis of the SAXS data showing a saturation of the growth of nanoscale crystallites. Comparison of simultaneously measured WAXS and SAXS data showed evidence of composition fluctuation prior to crystallization, suggesting that the crystallization was facilitated by nanoscale phase separation which established regions of favorable compositions catalyzing crystallization. The temperature dependence of crystallization mechanisms and the resulting microstructures in metallic glass are discussed.