Training of the Ni-Mn-Fe-Ga ferromagnetic shape-memory alloys by cycling in a high magnetic field

TL;DR

This study investigates how cycling in high magnetic fields influences the deformation and training of Ni-Mn-Fe-Ga ferromagnetic shape-memory alloys, revealing incremental deformation improvements with repeated cycles.

Contribution

It introduces a training procedure using magnetic field cycling to enhance the two-way shape-memory effect in Ni-Mn-Fe-Ga alloys, demonstrating measurable deformation increases.

Findings

Deformation increased with each cycle during martensitic transition.

Magnetic field influences deformation at constant temperature.

Incremental deformation observed up to 0.48% after three cycles.

Abstract

The temperature and magnetic field dependencies of Ni-Mn-Ga polycrystals deformation are investigated. Ingots were prepared by arc-melting in argon atmosphere and further annealing. A training procedure (cycling across the martensitic transition point) for the two-way shape-memory effect was performed with Ni$_{2.16}$Fe$_{0.04}$Mn$_{0.80}$Ga samples. Changes in sample deformations were noticed with changing the magnetic field at a constant temperature. The first cycle deformation increment as compared with the initial value (in the austenitic state at zero field) in the course of the martensitic transition was 0.29%, and 0.41% and 0.48% for the second and third cycles, respectively.