Space group and crystal structure of the R-phase in binary NiTi shape memory alloys
Acta Materialia 54(12): 3171-3175
The crystal structure parameters of the R-phase in a binary Ni50Ti49.2., shape memory alloy were redetermined using it device minimizing texture effects on neutron diffraction intensities. A sphere of 9 mm diameter Cut from a alloy which shows the R-phase state at room temperature was suspended oil an air cushion and kept in chaotic rotation motion while neutron diffractograms were obtained. Several models with different space group symmetries were tested in Rietveld refinements using the GSAS software. Our results clearly favour P (3) over bar symmetry, confirming the results of recent electron diffraction and X-ray diffraction Studies. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.