Synthesis and Magnetic Properties of τ-MnAlC Powders.

In order to improve the hard magnetic properties of MnAl alloy, it is critical to fabricate fine τ phase MnAl powders. In addition, a rapid cooling process and an addition of stabilization elements are required to fabricate a homogeneous phase because a τ phase is a metastable structure. In this study, τ-Mn54Al(46-x)C(x) (x = 0, 1, 2) powders were prepared by melt-spinning and subsequent annealing and milling processes. As a result, a main phase was revealed as a high temperature e phase in melt spun MnAI ribbons. And a subsequent annealing in the temperature range of 450-650 degrees C resulted in the formation of a τ phase. A maximum saturation magnetization (M(s)) value of 96.56 emu/g was obtained when the melt-spun τ-Mn54Al44C2 ribbons were annealed at 500 degrees C for 10 min. However, a milling process increased the coercivity up to 3804 Oe but simultaneously reduced M(s) down to 60.34 emu/g.