THEORETICAL AND EXPERIMENTAL STUDY OF THE STRUCTURE OF MONOCLINIC MARTENSITE IN NITI COMPOUNDS

V.E. Naish, T.V. Novoselova, I.V. Sagaradze

Institute for Metal Physics, Ural Division of RAS, Ekaterinburg, RUSSIA

Keywords: crystal structure, thermal vibrations, space group, lattice parameters, orientation relationship

The developed scheme for the theoretical analysis of structures of martensitic phases in crystals is applied here to the description of monoclinic phase in NiTi alloy . Such analysis enables the complete information about the structure of martensitic phase to be obtained, so as the new cell orientation relative the initial lattice, the lengths of the cell edges, the space symmetry group of the phase and the coordinates of all atoms of the cell.

We believe that one more structure of monoclinic phase can be realized in NiTi under different conditions (depending on the concentration of the basic components Ni and Ti or the concentration and type of dopants and so on). So the new structure of monoclinic phase with space group Cm is proposed here, which we have compared with experimental data along with traditional B19' model and the model of M-phase suggested early [1].

The Rietveld refinement of correspondent neutron diffraction data was made for all three models (two ours and one well known B19' model). These and other details will be presented in the full-length paper.

1. V.E.Naish, T.V.Novoselova, I.V.Sagaradze: The physics of metals and metallography, 80, N.5 (1995), 485-498.