THE LIMITATION OF MATANSITIC INVARIANT HABIT PLANE AND MARTENSITE MORPHOLOGY

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THE LIMITATION OF MATANSITIC INVARIANT HABIT PLANE AND MARTENSITE MORPHOLOGY

The strain tensor and displacement vector associated with lattice deformation were introduced to discuss the effect of self-accommodation and plastic accommodation in martensitic transformation,and the models for {557}_f and {3,10,15}_f martensite fomation were proposed, along with the experimental verification. It is considered that the invariant habit plane may result from the self-accommodation between different martensitic variants causing the internal twin structure. However, as the strength of parent phase is low enough for the plastic accommodation to occur the dislocation substructure in martensite be produced, in which case the invariant habit plane is difficult to form so the{225}_f and {557}_f habit planes are difficult to explain by the phenomenological crystallographic theory. So,there are some limitations for the martensitic invariant habit plane.In the present work the authors also suggest that the martensite morphology depends on the competition between self-accommodation and plastic accommodation including factors not only of strength but also of structure of the parent phase However, when the density of crystal defects is high dislocations rather than twinned martensite will form in spite of the higher strength of the parent phase.