Analysis of phase transformation kinetics by intrinsic stress evolutions during the isothermal aging of amorphous Ni(P) and Sn/Ni(P) films

Abstract

The kinetics for the crystallization of amorphous Ni(P) films and the formation of intermetallic compounds in Sn/Ni(P) films during isothermal aging treatment were studied with in situ intrinsic stress measurements. The intrinsic stress changes from crystallization were about 200 and 150 MPa for Ni(14P) and Ni(11.7P) films, respectively, and according to Johnson-Mehl-Avrami analysis, the Avrami exponents were about 3.6 +/- 0.46 and 4.2 +/- 0.39, and the activation energies were 242 and 240 kJ/mol, respectively, for the crystallization of Ni(14P) and Ni(11.7P) films. The stress due to the formation of intermetallic compounds such as Ni3Sn4 and MY in Sn/Ni(11.7P) films was about 320 MPa. Application of in situ stress measurements to the empirical growth model during isothermal phase transformation of Sn/Ni(P) showed that the intermetallic compounds growth was interface reaction-controlled (n = 0.91 +/- 0.08) in the early stage and then became diffusion-controlled (n 0.38 +/- 0.01), and the activation energy was about 35.9 kJ/mol.