Constraint-dependent twin variant distribution in Ni2MnGa single crystal, polycrystals and thin film: An EBSD study

The capability of showing large magnetically induced strains (MFIS) up to similar to 10% has attracted considerable research interest to magnetic shape memory (MSM) alloys. The prototype MSM alloy is the ternary Ni2MnGa. In this work, a comprehensive study of the local unit cell orientation distribution on single crystalline, polycrystalline and epitaxial thin film of martensitic Ni2MnGa is conducted by electron backscattering diffraction (EBSD). By EBSD, the constraint-dependent twin variant distribution, the corresponding stresses and the three-dimensional orientation of twin planes will be investigated. In polycrystals, the differentiation between twin and grain boundaries as well as proof of twin boundary motion is shown. From the knowledge of the local unit cell orientation at surfaces, it is possible to explain the magnetic domain configuration imaged by magnetic force microscopy. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.