Synthesis and Magnetic Properties of tau-MnAlC Powders

Abstract

In order to improve the hard magnetic properties of MnAl alloy, it is critical to fabricate fine tau phase MnAl powders. In addition, a rapid cooling process and an addition of stabilization elements are required to fabricate a homogeneous phase because a tau phase is a metastable structure. In this study, tau-Mn54Al46-xCx (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 a phase in melt spun MnAl ribbons. And a subsequent annealing in the temperature range of 450-650 degrees C resulted in the formation of a tau phase. A maximum saturation magnetization (M-s) value of 96.56 emu/g was obtained when the melt-spun tau-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.