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 made of alloy of polycrystalline Mn-Al-C system that has been made anisotropic is compressed in the axial direction at the preselected temperature in such a manner as to make free at least part of its internal and external peripheries. 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 compression-processed at the temperature range of 530-830 deg.C in such a state that at least part of the internal and external peripheries thereof is set free. In the case of the uniaxial anisotropic magnet, compressive stress must be 0.05 or more at the logarithmic value. With this construction, the magnets of both the anisotropic types display high magnetic characteristics in the diametric direction and the part locally compression- processed has higher magnetic characteristics in the diametric direction, so that flaws such as uneven transformation or a permanent band can be avoided.