Method for the preparation of alloys of the rare earth metals of the SE.sub. Fe.sub.17-x TM.sub.x N.sub.y type

US5482572A · kind A · utility

Assignee

• Th. Goldschmidt. AG · DE

Inventors

• Horst Eggert · Berlin, DE
• Michael Steinhorst · Essen, DE

Key dates

• Filing date: Oct 21, 1993
• Grant date: Jan 9, 1996
• Expiry date: Oct 21, 2013

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B22F2201/02
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A method for the preparation of alloys of the SE.sub.2 Fe.sub.17-x TM.sub.xN.sub.y type where SE stands for a rare earth metal, including Y or a mixture of these metals, while TM stands for Co, Ni, Cu, Zr, Ga, Hf, Ta, Nb, Ti, Si, A1, V, Mo, Cr, Zn or Sn or a mixture of these metals, x=0 to 10, y=>0 to 5 is described. The preparation involves calciothermal reduction of a finely divided, homogeneous mixture of the alloying components, subsequent diffusion of the components, followed by nitriding and separating the calcium oxide and excess calcium formed. The method is characterized by: PA0 a) Preparation of an alloy of the SE.sub.2 Fe.sub.17-x TM.sub.x by PA1 a1) Adjusting the exothermic reaction of the calciothermal reduction by the oxide content of the reaction mixture, so that T.sub.M >TR .gtoreq.0.9 T.sub.M where T.sub.M is the melting temperature of the intermetallic phase, and T.sub.R is the reaction temperature, PA1 a2) Using a reaction mixture having components, excepting calcium, of an average particle size of .ltoreq.75 .mu.m, PA1 a3) tempering the reaction product at the end at a temperature at least 0.7 times the melting temperature T.sub.M of the desired alloy, but less …