Moessbauer effect study on the mechanism of the phase decomposition in iron-chromium alloys

The concentration and temperature dependences of the incubation time, the analysis of the transformation rate based on the Johnson-Mehl equation, and the time evolution of the Moessbauer spectrum suggest that the nucleation and growth process plays a dominant role in the phase decomposition of Fe-Cr alloys around 748 K in the concentration range from 21 to 36.3 % Cr. The spinodal decomposition becomes predominant in the concentration range from 42 to about 60 % Cr. The decomposition mode shows a gradual transition from the nucleation and growth to the spinodal decomposition with increasing Cr content. (author)