Stable Magnetic-Field-Induced Strain Above 1% in Polycrystalline Ni–Mn–Ga

Polycrystalline Ni-Mn-Ga samples were directionally solidified and trained in order to lower the twinning stress. Polyurethane was used to fill the cracks. Magnetic-field-induced strain (MFIS) was measured in a rotating magnetic field over more than 10(6) cycles. The operating temperature was varied between 0 and 45 degrees C. With increasing temperature, the MFIS increased from 0.6% to 1.2%. After cooling to room temperature, an enhanced MFIS of 1.0% was retained and maintained over another 10(6) cycles. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.