自動車に関連する粉体および粉末冶金技術 メカニカルアロイング法により作製したＭｎ‐Ａｌ‐Ｃ合金粉末の磁気特性

Abstract

Mn, Al, and C powder mixtures were mechanically alloyed using a conventional ball mill and a high-energy ball mill in an argon atmosphere. Although the mechanically alloyed powders prepared by the conventional ball mill retained the original powders, the powders prepared by the high-energy ball mill did not retain the original powders and consisted of α-Mn solid solution. However, no intermetallic compounds such as the magnetic τ phase and high temperatures e phase were formed during the mechanical alloying. The magnetic τ phase was obtained by subsequent annealing of the mechanical alloyed powders as was the case for the gas atomized powders. It was found that annealing of the powder mixture, without mechanical alloying, resulted in the formation of the small amount of the magnetic τ phase. However, the mechanical alloying significantly increased the amount of the magnetic τ phase in the annealed powders. This was due to the thorough mixing of Mn, Al, and C powders by the mechanical alloying. The magnetic properties of the annealed powders were deeply dependant on the annealing temperature. The optimally annealed mechanical alloyed powders showed a large saturation magnetization with a high coercivity comparable to those gas atomized counterparts.