Fabrication of permanent magnets without loss in magnetic properties

Abstract

A method is provided for forming high coercivity permanent magnets from a rare earth-iron-boron metal, wherein the permanent magnets exhibit high intrinsic coercivity comparable to that of the rare earth-iron-boron metal alloy when formed by machining and appropriately heat treating the metal alloy in air at a temperature greater than the Curie temperature of the material, prior to or after the machining operation. As a result, high coercivity permanent magnets can be selectively sized and shaped to satisfy specific design requirements, without requiring that a punch and die be specially designed and manufactured to produce the permanent magnets. The heat treatment method is able to promote machinability of the metal alloy without substantially causing a loss in magnetic properties. Alternatively, the heat treatment method can be employed to substantially restore the magnetic properties of a permanent magnet which were previously reduced by conventional annealing practices.