Composition dependence of crystal growth and its time evolution in supercooled liquid of Zr-Al-Cu glassy metals

Crystal nucleation and its time evolution during isothermal annealing in supercooled liquid of glassy metals Zr65Al10Cu25 ribbon, Zr50Al10Cu40 ribbon, and Zr50Al10Cu40 bulk are examined using a technique of differential thermal analysis. Time dependence of the fraction of crystallization in supercooled liquid at several temperatures is analyzed by the Johnson-Mehl-Avrami (JMA) formula. The Avrami exponents are 3.0 ± 0.2 for Zr65Al10Cu25 ribbon, and 3.9 ± 0.4 for Zr50Al10Cu40 ribbon and Zr50Al10Cu40 bulk. Relation between grown crystals in the supercooled liquid and the Avrami exponent can be explained reasonably. Plots of the fraction of crystallized volume versus a scaled time normalized by the half time of full crystallization almost collapse on a single curve. This suggests that the crystal growth obeys a universal process. The temperature dependence of the half time is discussed using the Williams-Landel-Ferry function.