Khalil-Allafi, Jafar; Schmahl, Wolfgang W.; Többens, D. M.
Space group and crystal structure of the R-phase in binary NiTi shape memory alloys.
In: Acta Materialia, Vol. 54, No. 12: pp. 3171-3175
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The crystal structure parameters of the R-phase in a binary Ni50Ti49.2.,shape memory alloy were redetermined using it device minimizing textureeffects on neutron diffraction intensities. A sphere of 9 mm diameterCut from a alloy which shows the R-phase state at room temperature wassuspended oil an air cushion and kept in chaotic rotation motion whileneutron diffractograms were obtained. Several models with differentspace group symmetries were tested in Rietveld refinements using theGSAS software. Our results clearly favour P (3) over bar symmetry,confirming the results of recent electron diffraction and X-raydiffraction Studies.