Twin boundary nucleation and motion in Ni-Mn-Ga magnetic shape memory material with a low twinning stress

The twin boundary motion in the Ni-Mn-Ga single crystal 10M martensite magnetic shape memory material was studied by mechanical twinning stress and magnetic measurements at ambient temperature. The compressive stress required to trigger the movement of the twin boundaries was higher in the sample with the single variant state than in that with the multivariant state. Magnetometer measurements confirmed that the energy needed to move the twin boundaries in a high-quality single crystal 10M Ni-Mn-Ga is lower than that for the nucleation of a twin boundary. (C) 2009 Acta Matcrialia Inc. Published by Elsevier Ltd. All rights reserved.