The crystallization kinetics and microstructural dynamics associated with devitrifying a meltspun Cu 50 Zr 50 metallic glass were investigated using isothermal treatments, in situ high-energy synchrotron X-ray diffraction, conventional and high-resolution transmission electron microscopy, and differential scanning calorimetry. The analysis of isothermal transformations allows us to more clearly unravel the complex interplay between nucleation and growth of competing stable and metastable phases. The isothermal devitrification response was found to involve the Cu 10 Zr 7 , CuZr 2 , and CuZr phases, consistent with previously reported constant heating rate experiments, but here we have resolved the phase evolution and structural characteristics of the transformation, including the very early stages of crystallization. At 671 K (398°C), the isothermal transformation starts with the formation of the Cu 10 Zr 7 phase, which grows in a generally equiaxed morphology. At a size of approximately 100 nm, the growth of the Cu 10 Zr 7 particles is interrupted by the precipitation of a thin layer of the CuZr 2 phase, upon which the metastable CuZr (B2) grows epitaxially. Crystallization kinetics are quantified here though in situ measurements (HEXRD, DSC) and ex situ microstructural analysis (TEM, HRTEM). Finally, the influences of chemical partitioning, diffusion, and crystallographic orientation on this sequence are examined.

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