Continuous refinement of the microstructure during crystallization of supercooled Zr41Ti14Cu12Ni10Be23 melts

Abstract

Isothermal crystallization studies are performed on Zr41Ti14Cu12Ni10Be23 melts between the liquidus and the glass transition temperature. The resulting time–temperature-transformation diagram is in good agreement with the data obtained from containerlessly processed samples. The various solidification products are examined by electron microprobe. The investigations reveal the morphology and typical length scale of the microstructure as well as the primarily solidified phases after crystallizing at different degrees of undercooling. The typical length scale decreases continuously with increasing supercooling over five orders of magnitude. The number density of nuclei during primary crystallization is estimated from the microstructure. The results are discussed within several models, such as steady-state nucleation, spinodal decomposition, and a nonpolymorphic nucleation model.