Permanent Mn-Al-C alloy magnets and method for making same.

摘要

A billet made of a polycrystalline Mn-AI-C alloy magnet which is obtained by plastically deforming a Mn-AI-C alloy for magnet such as by extrusion at a temperature of 530 to 830°C is used for compressive working. When the billet is hollow, it is entirely or locally compressed along the axis of the hollow billet. On the other hand, when the billet is solid, an outer circumferential portion of the billet is compressed. By the compression, the anisotropic structure of the portion where compressed is changed into an anisotropic structure having a direction of easy magnetization in radial directions. The magnet obtained by the method is also disclosed. The magnet has a radially anisotropic structure or novel structures having two different types of anisotropies therein.