High-chromium ferritic steels -: Microscopic reasons for brittleness and hardness studied by Mossbauer effect

Relevance of the Mossbauer Spectroscopy (MS) in the investigation of microscopic reasons for brittleness and hardness of high-chromium ferritic steels is demonstrated and discussed. It is shown that MS is a suitable tool to study (i) the formation of the sigma phase and (ii) the phase decomposition into Fe- and Cr-rich phases, the two phenomena responsible for degradation of the steel properties. The uniqueness of MS in the investigation of the latter phenomenon is underlined and its ability of making distinction between nucleation and growth, on one hand, and spinodal process, on the other, is emphasized.