The incommensurate modulations of stoichiometric Ni2MnGa

We use X-ray diffraction to confirm that the 5M phase of the stoichiometric Hensler alloy Ni2MnGa has an incommensurate modulation with wavevector q = [0.428 0.428 0]. We find the crystal to be macroscopically twinned with a structure well described by the theory of martensitic phase transitions, though theoretical calculations of the X-ray diffraction rule out the existence of an adaptive phase. The premartensite phase is found to be slightly incommensurate with q =[0.341 0.341 0]. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.