CRYSTALLOGRAPHIC ANALYSIS OF THE LATH MARTENSITE TRANSFORMATION IN Fe-Ni-Mn ALLOY

Habit plane rotation of lath martensite transformation in Fe-Ni-Mn alloy was predicted by means of Displacement Vector Theory. Its surface relief effect was observed and a math model for the quantitative analysis of habit plane rotation of lath martensite transformation was established by means of atomic force microscopy (AFM). The experiment showed that the largest rotation of habit plane of lath martensite transformation predicted by means of Displacement Vector Theory is 13.50°, and it′s incompatible with the concept of invariant plane strain (IPS); surface relief of lath martensite revealed no character of IPS, i.e. it exhibited irregular "N"-shaped "surface relief packet", and "surface relief packet" was composed of layers of several small surface reliefs, the AFM quantitative analysis of habit plane rotation of lath martensite transformation was 11.11°, which was in agreement with the prediction of Displacement Vector Theory (13.50°) and it firmly confirmed the habit plane rotation of lath martensite transformation and the correctness of Displacement Vector Theory.