Effect of powder particle size, extrusion temperature and mean strain rate on anisotropy of MnAlC alloy was investigated. The anisotropy proceeding mechanism of MnAlC alloy was considered by anisotropy investigation with specimens during exrusion.
MnAlC powder was made by Ar gas atomizing process, classified fixed particle sizes and was compacted by extrusion at extrusion temperature: 853-993K and mean strain rate: 0.005-0.05/s.
Anisotropy of MnAlC formed was found to improve at lower temperature, finer particle size and lower strain rate. It was considered to be related to the homogeneity of τ phase and the crystal grain size. It was found that anisotropy of MnAlC magnet was increased as deformation right after the start of extrusion and saturated at the part on the way of extrusion.
This phenomenon can be explained by the two deformation areas, one is that dynamic recrystallization proceeds as keeping the former crystal orientation according to the strain induced grain boundary migration mechanism, the other is that dynamic recrystallization proceeds with no relation to the former crystal orientation according to the nucleation and growth mechanism.