Crystallization Kinetics of Ti-Zr-Ni-Cu Metallic Glasses

It was found that the Ti 45-x Zr x Ni 45-z Cu z (0 ≤ x ≤ 10, 0 ≤ z ≤ 10) metallic glasses crystallize polymorphously and the crystal phase forms a solid solution of Zr and Cu in the TiNi phase. Differential scanning calorimetry (DSC) was used to study the crystallization kinetics of Ti-Zr-Ni-Cu metallic glasses near glass transition temperature. The fraction transformed y, as a function of time are of sigmoidal type at each temperature. For 0.10 ≤ y ≤ 0.85 the plots satisfy the Johnson-Mehl-Avrami equation and approximate to straight lines with exponent n varying from 3.1 to 3.9 as the annealing temperature increases. The activation energy for the crystallization of Ti 45 Zr 5 Ni 45 Cu 5 metallic glass estimated from the temperature corresponding to 50% transformation is close to 380 kJ/mol.