Magnetic properties of Mn-Al system alloys produced by mechanical alloying

Mechanical alloying of Mn-Al and Mn-Al-C powder mixtures resulted in the formation of alpha-Mn solid solution. Heat treatment of these mechanically alloyed powders resulted in the formation of the metastable tau phase. The mechanically alloyed powders annealed at relatively low temperatures (500-700 degreesC) showed small saturation magnetization of less than 1 emu/g in both Mn-Al and Mn-Al-C powders. On the other hand, the Mn-Al powders showed saturation magnetization of 8 emu/g and their Mn-Al-C counterparts exhibited large saturation magnetization of more than 20 emu/g when annealed at relatively high temperature (800-1100 degreesC). Although the annealed Mn-Al powders showed small coercivity, the Mn-Al-C powders exhibited large coercivity, up to 3.3 kOe, after selected heat treatment. (C) 2003 American Institute of Physics.