Comparison of Recrystallization Kinetics and Grain Growth in Shape Memory Alloys

Grain growth behaviors of Cu-14Al-4Ni, Cu-12Al-0,5Be e Ni-42Ti have been systematically investigated for various temperatures. The study of kinetics of recrystallization is important for enabling the control of hardened state as a function of treatment time. Quantitative evaluations of the grain growth kinetics over a wide range of temperatures from before the beginning to after the end of the DSC´s curves have been performed. The results show that the alloy less susceptible to aging for temperatures below the recrystallization peak is the Ni-42Ti, because presented the highest activation energy, followed by the Cu-14Al-4Ni. The equations describing the recrystallization kinetics follow the empirical law Johnson-Mehl-Avrami. The recrystallization kinetics accompanied by hardness variation was an important tool, acting as advisor for selection of treatment times as a function of temperature. Cu-12Al-0,5Be probably is heterogeneous, because presented the best and the worst correlation factor, and not presented a double recrystallization kinetics.