Effect of Annealing on Microstructure and Functional Properties of Ni-Mn-Ga-Cu Alloys Produced by Melt Spinning Technique

Abstract

In this work, we have performed experimental measurements and analysis of the annealing effect in the temperature range of 100°C-900°C on the magnetic field-induced bending phenomenon of Heusler alloys with the nominal composition of Ni50Mn30Ga18Cu2. The annealing process resulted in an increase of the average grain size. Annealing also affected the magnetic field-induced bending effect, increasing the maximum value of the obtained normalized deflection by about six-fold. However, this effect occurred in the case of ribbons annealed at higher temperatures, i.e. above 500°C. Annealing also led to a reduction in the magnetic field value required to activate the magnetic field-induced bending effect. The annealing process in the range from 500°C to 900°C affected both the amplitude and the maximum value of the normalized deflection. The presented results demonstrate that through heat-treatment the functional properties of the analyzed Ni-Mn-Ga-Cu ribbons, obtained by the melt spinning method, can be effectively optimized.