Abstract
Magnetic properties of Mn-AI-C alloy magnets produced from gas-atomized alloy powders were improved by using the finer particles because the cell size and the segregation of finer particles were very small. So, by using more rapidly solidified powders, the excellent characteristics of Mn-Al-C magnet was expected. In this work, the effect of the rapidly quenched ribbon on the characteristics of Mn-Al-C alloy was investigated, and discussed from the point of rapid solidification. The specimen were prepared by the rapid solidification apparatus with the single roll in the Ar gas atmosphere. Phase analysis of as-quenched and after heat treatment was done by X-ray diffraction analysis. Magnetic properties were estimated on the magnet made from the powder-extrusion process. Tile magnetic properties of Mn-Al-C alloy were improved by using of more rapidly solidified ribbons. Br, iHc, (BH)max and anisotropy of ferromagnetic T-phase were improved to higher level by using thiner thickness ribbons. At extrusion ratio 4, (BH)max value of 57.lkJ/m3 was obtained by the magnet prepared from rapidly solidified ribbons of 12gm average thickness, which was much higher than that by cast process or by gas atomization process. The improvement of magnetic properties of the extruded magnet from rapidly solidified ribbons was found to be caused by the finer microstructure and very small amount of non-magnetic phases such as γ2-phase and β-phase.
