Structural Study of the R-Phase in Ti-Ni Alloy by the Rietveld Method

The crystal structure of the R-phase in Ti-Ni alloy is determined by the X-ray powder diffraction method. The Pawley method (whole powder pattern decomposition method) and the Rietveld method were used for the analysis. The results of the analysis indicate the space group of the R-phase is P3 rather than P31m. The atomic positions obtained are compared with those of Au-Cd. The transformation mechanism is also discussed in comparison with that for Au-Cd alloy