Nanocrystallization of Zr61Al7.5Cu17.5Ni10Si4 metallic glass

The primary nanocrystallization behavior and microstructural evolution of the Zr61Al7.5Cu17.5Ni10Si4 alloy during annealing were investigated by isothermal differential scanning calorimetry, X-ray diffractometry and transmission electron microscopy. During continuous heating of the 4Si and the base (contains no Si) amorphous alloys at a heating rate of 10 K/min, the saturation point of nucleation for the 4Si amorphous alloy occurs at a crystallization fraction of 78%, which is significantly higher than 65% for the base alloy, implying that these metalloid atoms would extend the nucleation stage and refine crystalline particles. The sequence of crystallization phase from the amorphous matrix for the isothermally annealed 4Si amorphous alloy at 703 K is observed to be Zr2Cu and Zr2Ni at the early stage, Zr3Al at an intermediate stage, and Zr2Si at the final stage. Moreover, enrichment of Si atoms at the interface between Zr2Cu crystal and the amorphous matrix is detected. This may result in increasing the thermal stability of the remaining amorphous phase and retardation of the crystal growth of Zr2Cu particles.