Crystallization of amorphous Zr60Al15Ni25 alloy

The phase formation and crystallization kinetics during the thermal treatment of amorphous Zr60Al15Ni25 alloy were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). By lowering the isothermal annealing temperatures, it is revealed that the crystallization of the amorphous Zr60Al15Ni25 alloy consists of a primary transformation followed by a polymorphic transformation, corresponding to the precipitations of hexagonal Zr6Al2Ni and the Zr5AlNi4 with a U3Si2-typed superstructure. The primary phase being Zr6Al2Ni rather than Zr5AlNi4 in the crystallization is because the latter has a complex structure and its formation requires the diffusion of Al and Zr atoms on a large scale.