Theoretical Analysis of Possible Martensitic Phases in Titanium Nickelide

Abstract
The concept of co-operative thermal vibrations in crystals is applied here for an independent analysis of a system of martensitic phase transitions in titanium nickelide (NiTi). In addition to the orthorhombic B19 phase, which is well known for NiTi, a trigonal and a monoclinic phase - have been produced and are analyzed in detail. The calculated and experimental neutron diffraction patterns obtained for monoclinic and trigonal phases show a good agreement. The obtained structure of the monoclinic phase is absolutely different from the B19' structure described in the literature. Finally, more emphasis is placed on some complicated problems associated with a detailed identification of the trigonal phase structure.