The kinetics of the thermal devitrification of the TiNi-TiCu amorphous alloy

Investigation of the devitrification process of the amorphous alloy of the composition 50 Ti, 45 Cu and 5 at% Ni was performed by differential scanning calorimetry (DSC). It was shown that devitrification occurs in two steps. The first step corresponds to the process of thermal relaxation of the amorphous state without crystallization at 674.5 K ( β = 20 K/min.). The second step presents real crystallization at 741.7 K ( β = 20 K/min.) during which polycrystallites of intermetallic phases TiCu and TiNi are formed. The kinetic and thermal parameters of both steps of devitrification were determined. The activation energy is E 1 = 446.93 kJ/mol for the first, and E 2 = 288.74 kj/mol for the second step; the frequency factor for the first step is Z 1 = 1.66 × 10 −35 min. −1 and Z 2 = 2.72 × 10 −20 min. −1 for the second one. The enthalpy of the first step is ΔH 1 = −17 J/ g of the second ΔH 2 = −469 J/ g. The dependence of the crystallization rate constant on temperature was also shown.