Magnetic-field-induced decomposition in Cu2MnAl Heusler alloys

Abstract A magnetic field enhanced the decomposition of a Cu2MnAl Heusler alloy. An aging treatment at 573 K under 10 T promoted decomposition of a L21 phase and hard magnetic properties were exhibited. The crystallite size of the L21 phase decreased on annealing over 12 h and approached 22 nm at zero field. However, the crystallite size of the L21 phase of the 5 T-annealed sample was almost half that of the 0-T-annealed sample and decreased rapidly, indicating enhanced grain refinement by in-field annealing. Decomposition of the L21 phase was more pronounced in the 10-T-aged sample. The hysteresis loop for 10-T-aged sample had a large coercive force of 232 mT and a magnetization of 13 Am2/kg. These properties were markedly different from those of the 0-T-annealed sample. An increase of nucleation owing to a decrease of critical radius caused grain refinement associated with decomposition and magnetic hardening of Cu2MnAl.