STUDY OF PR-FE-B-CU PERMANENT-MAGNETS PRODUCED BY UPSET FORGING OF CAST INGOT

An attempt was made to produce anisotropic Pr-Fe-B-Cu-type permanent magnets from the cast ingot materials using an upset forging process. The effects of the casting condition of the ingot on the magnetic properties of the upset forged magnets were investigated. Most of the free iron which existed in the cast ingot material was removed by upset forging at high temperatures (approximately 900-degrees-C), and this was achieved by a solid-liquid peritectic reaction between the free iron and the praseodymium-rich grain boundary phase thought to be aided by cracks in the Pr2Fe14B matrix grains caused by the upset forging. The magnetic alignment of the upset forged magnets can be explained by grain boundary gliding of the plate-like ferromagnetic matrix grains. A Pr-Fe-B-Cu magnet ((i)H(c) approximately 12.0 kOe, B(r) approximately 10.5 kG) with good demagnetization character was produced by the upset forging of the ingot material at 900-degrees-C.