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.