PREPARATION OF MANGANESE-ALUMINUM-CARBON ALLOY MAGNET

摘要

PURPOSE:To obtain a magnet having high magnetic characteristics in the diametric direction with small compressive stress by a method wherein a hollow steel piece of magnet of polycrystalline Mn-Al-C system that has been made anisotropic is provided with compressive stress by extruding the piece in parallel with the axis using dies of preselected shape at the preselected temperature. CONSTITUTION:A known alloy of Mn-Al-C system for preparing a magnet is extrusion-processed at 530-830 deg.C to obtain a uniaxial or facial anisotropic magnet. A hollow steel body 1 of the magnet is compressed in the diametric direction with dies 2, 3 and punches 4, 5 at 530-830 deg.C. A space 6 for containing the steel body before processing is hollow and its opening area is narrower than that of a space 7 after extrusion processing. In the case of the uniaxial anisotropic magnet, the compressive stress is set at 0.05 or more at the logarithmic value. With this construction, any anisotropic magnet displays high magnetic characteristics in the diametric direction.