Martensitic Transformations : Microstructures and Uniaxial Stress, Magnetic Field and Hydrostatic Pressure Effects

Microstructures in martensites and effects of uniaxial stress, magnetic field and hydrostatic pressure on martensitic transformations, which were investigated by the author, are briefly summarized. Unsolved problems related to this investigation are pointed out and some ideas are proposed to solve the problems. Interactions between lattices and electrons should be clarified in order to establish the cause of martensitic transformation. In particular, the exact electronic band structure at Brillouin zone boundaries should be delineated, and whether martensitic nuclei are indeed grown from precursory strained regions in matrix phases should be clarified. How the precursory strained region is related to the lattice invariant strain considered in the phenomenological crystallographic theory for martensitic transformations and actually observed by TEM should also be clarified. Some other future research subjects, such as the effects of uniaxial stress, magnetic field and hydrostatic pressure on martensitic transformations, and various related functions, such as shape memory effect and superelasticity, are further pointed out.