Different modeling concepts of magnetic shape memory and their comparison with some experimental results obtained in Ni-Mn-Ga

Starting from the realistic experimental picture of twin and magnetic domain microstructure we represent a consistent model of magnetic shape memory taking into account all the most important energy contributions. We also perform a detailed analysis of some other models and discuss their quantitative applicability to some experimental results obtained for Ni-Mn-Ga. Performing mechanical testing experiments in all the different martensitic phases of Ni-Mn-Ga under the constant magnetic field applied perpendicular to the load direction we show that such a magnetic field can dramatically modify standard zero field strain stress relationships of magnetic shape memory alloys (MSMAs) like Ni-Mn-Ga. In a particular case of 5 and 7M martensites we observe a so-called pseudo-elastic or rubber-like behavior during the standard compression-decompression cycling under the field at about 1 T. This effect is finally discussed from the point of our modeling concept. (C) 2004 Elsevier B.V. All rights reserved.