Ferromagnetism of manganese-aluminium alloyed with 0–3% carbon from direct induction melting and subsequent annealing

Abstract

The transformation from ε to τ phase is investigated in manganese-aluminium (Mn55Al45) alloyed by the induction melting. By annealing Mn55Al45 at 450–550°C for 2 h, the ferromagnetic τ-MnAl is enhanced at the expense of ε phase. The largest coercivity of 1139 Oe and remanent magnetization of 3.71 emu/g are obtained after annealing at 550°C. The additions of 1 and 2% carbon affect the phase and magnetic properties of Mn55Al45 but the 2 h annealing at 550°C still leads to the largest coercivity. Interestingly, substantial coercivity and magnetizations are directly obtained in (Mn55Al45)98C2 and (Mn55Al45)97C3 by the induction melting without further heat treatments.