Magnetic Forces Controlling Magnetic Shape Memory in Ni-Mn-Ga and Their Practical Measurement From the Mechanical Testing Experiments in Constant Magnetic Fields

摘要

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 MSMA's like Ni-Mn-Ga. In a particular case of 5M 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 1T. This effect is finally discussed from the point of the general thermodynamic background and some particular modeling concepts.