홍민종 , 조재섭 , 김도향 , 김용석 Min Jong Hong , Jae Seob Cho , Do Hyang Kim , Yong Seog Kim
Abstract
Diffusion kinetics for growth of NiTi at Ni/Ti interface has been investigated. The temperature dependence of the intrinsic diffusion coefficient of Ni, Ti in NiTi intermetallic compound was obtained by D_(Ni)(NiTi) (㎠/sec) = 9.8401×10^(-6)·exp(-95950/RT) and D_(Ti)(NiTi)(㎠/sec) = 1.9111×10^(-5)·exp(-101730/RT). The activation energies of the intrinsic diffusion coefficients of Ni, Ti are 9.5950(±0.84)×10⁴(J/㏖) and 10.173(±3.02)×10⁴(J/㏖) respectively. The parabolic growth constant(k_p^(NiTi)(㎠/sec)) of NiTi calculated by using the equations given by Shatynski. Hirth and Rapp was 1.0797×10^(-5)·exp(-109980/RT) for the temperature range between 800 and 950℃. The activation energy of the growth rate constant is 1.0998(±0.17)×10^5(J/㏖). Present study suggests that the calculation of growth rate constants by the method of Shatynski, Hirth and Rapp can be applied successfully when the interface layer growth follows the parabolic law.