The effect of temperature on the crystallization of Zr₅₅Cu ₃₀Al₁₀Ni₅ bulk metallic glass in the glass transition region

In this paper, the effect of temperature on the isothermal crystallization of Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass in the glass transition region was investigated by differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. It was found that the crystallization behaviour of Zr₅₅Cu₃₀Al ₁₀Ni₅ bulk metallic glass strongly depends on the annealing temperature. The crystallization follows a diffusion-controlled growth mechanism with the formation of a dendritic-like structure in the high temperature region from 743 to 753 K. However, it follows two different mechanisms, i.e. diffusion-controlled and interface-controlled, with the formation of both dendritic-like and spherical structures, respectively, in the low temperature region from 723 to 739 K. Furthermore, the activation energy for crystallization from supercooled liquid is also temperature-dependant. The apparent activation energy is about 212 kJ/mol in the high temperature region, but 314 kJ/mol in the low temperature region. The different crystallization behaviour is believed to be due to the different structures that the metallic glass possesses at different temperatures.