Magnetic field-induced stress in the Ni–Mn–Ga magnetic shape memory alloy

Abstract

Magnetic Shape Memory ͑MSM͒ materials generate stress in a magnetic field, which can change the shape of the material. Up to now, little work has been carried out in modeling and measuring the magnetic field-induced ͑MFI͒ stress in MSM materials. In the present study, direct MFI stress measurements in a Ni-Mn-Ga MSM material, giving full 6% MFI strain, were performed at different field strengths. The MFI stress was also calculated from the magnetic anisotropy of the material, based on the magnetization curves along the easy and the hard magnetization directions. Both measurement methods are described in detail. The measurement results demonstrated good agreement with the calculated ones. The dependence of the MFI stress on the MFI strain and the magnetic field strength was also revealed. Potential errors during MFI stress measurements in MSM materials are discussed, and avoided by properly selecting the measurement conditions during the study.

Fracture mechanism of a Ni–Mn–Ga ferromagnetic shape memory alloy single crystal

“…They can create a magnetoelastic strain of up to 10% in some nonstoichiometric Ni-Mn-Ga alloys [1][2][3][4]. This is 50 times larger than the best-performing and fastresponding actuator materials, like piezoceramics or magnetostrictives (e.g.…”

Thermally induced fracture of single crystal Ni–Mn–Ga ferromagnetic shape memory alloy

“…Such a giant magnetic field-induced strain (MFIS) is related to the motion of twin boundaries [4,5] driven by magnetic field-induced stress (magnetostress) carried by twin dislocations [6][7][8][9]. To obtain this large strain, both high magnetocrystalline anisotropic energy and low detwinning stress (1-3 MPa) are necessary.…”

Model on Electromagnetic-mechanical Conversion of Magnetically Controlled Shape Memory Alloy

“…Reference [7] gives the measurement method of the magnetization curve, which is shown as in Fig.1. The expression of the easy and hard magnetization curve can be got from Fig.1 respectively:…”