Thickness dependence of the crystallization process of wedge-shaped Zr70Cu27.5Rh2.5 metallic glass prepared by ion milling

Crystallization happens when metallic glass is annealed at elevated temperature. It has been believed that the crystallization process is primarily determined by the metallic glass composition with no report and expectation that it may depend on the physical dimension. In the present work, in situ annealing experiment was performed on a Zr₇₀Cu_27.5Rh_2.5 metallic glass under transmission electron microscopy observation. The specimen is prepared by ion milling and is wedge-shaped with its edge thin enough to be transparent for 200 keV electrons. At annealing condition well beyond that required for full crystallization for the regular ribbons, crystallization was not observed in areas with thickness of approximately 250 nm while crystalline grains in the thin and thick neighboring areas were observed.