Metamagnetic behavior in L10-MnAl synthesized by the post annealing of electrodeposited MnAl powder

The effect of annealing temperature on MnAl alloy powder synthesized by electrodeposition method was investigated. Single L10-MnAl (τ-phase) with nearly stoichiometric composition was obtained by electrodeposition method. In annealed at 400°C sample coercivity of 12.3 kOe was observed. And by annealing at 450–550°C, metamagnetic behavior was observed. In these samples, the main phase was τ-phase although weak peaks of low-temperature Al-rich γ2 phase appeared. The order parameter S of the τ-phase exhibited a peak value with variation of the annealing temperature. The peak value was 0.90 at an annealing temperature of 500°C, where the metamagnetic behavior was most clearly observed. This indicates that the nearly perfectly ordered τ-phase shows metamagnetism and the Mn atoms occupying the Al sites play an important role in the metamagnetism of the τ-phase.