Abstract: It is an object of the present invention to provide a process of producing calcined materials for ferrite magnet, whereby foreign phase produced in calcined powders is eliminated and the ferrite magnet having a superior magnetic properties is obtained easily. Since mill scales roughly milled into a mean particle size of 20 .mu.m or less is subjected to primary oxidation treatment to change its oxidation percentage 95% or higher, and oxidized completely by secondary oxidation treatment in an inclined rotary kiln up to 700.degree. C. in an atmosphere containing O.sub.2 content of 8% to 10% at a charging side of raw material, foreign phase is not produced in the calcined powders during ferrite formation at high temperatures, and the ferrite magnet having a superior magnetic properties can be obtained.

Abstract: A powder for producing permanent magnets, comprising a blend of powders [A] and [B] or [C] wherein:alloy powder [A] has an R.sub.2 Fe.sub.14 B phase and contains, in atomic percent, from 11 to 13% of at least one rare element, R, inclusive of Y, from 4 to 12% of B, and the balance Fe; or optionally, said powder has an R.sub.2 (Fe,Co).sub.14 B phase, an R.sub.2 (Fe,Ni).sub.14 B phase or an R.sub.2 (Fe,Co,Ni).sub.14 B phase, containing at least one selected from the group consisting of 10% or less of Co and 3% or less of Ni as a partially substitute for Fe;powder [B] is an intermetallic compound having an intermetallic compound phase of R with Fe or Co inclusive of an R.sub.

Abstract: To obtain an anticorrosive Fe-B-R type permanent magnet; in particular, to reduce deterioration rate of the initial magnetic properties below 10% after the magnet has been kept at 80.degree. C. in 90% relative humidity for 500 hours, the surface of the sintered permanent magnet is coated with metallic coating film layers of at least one noble metal layer and at least one base metal layer disposed on the noble metal layer. Diffusion heat treatment further improves the adhesiveness of the coating film layers.

Abstract: A corrosion-resistant R-Fe-B type sintered permanent magnet exhibiting deterioration of not more than 5 % from the initial magnetic properties after being tested for 500 hours under the conditions of a temperature of 80.degree. C. and a relative humidity of 90 % is produced by:causing at least one colloidal noble metal selected from the group consisting of Pd, Ag, Pt and Au to be adsorbed in a colloidal state or forming a thin layer thereof through vapor deposition on the surface of the sintered body; applying at least one base metal selected from the group consisting of Ni, Cu, Sn and Co containing P and/or B by electroless plating; and further applying at least one base metal selected from the same group.The noble metal layer is 1-10 nm thick. The electroless plating layer is no more than 10 .mu.m and the electrolytic plating layer 5-60 .mu.m thick.

Abstract: To obtain an anticorrosive Fe-B-R type permanent magnet; in particular, to reduce deterioration rate of the initial magnetic properties below 10% after the magnet has been kept at 80.degree. C. in 90% relative humidity for 500 hours, the surface of the sintered permanent magnet is coated with metallic coating film layers of at least one noble metal layer and at least one base metal layer disposed on the noble metal layer. Diffusion heat treatment further improves the adhesiveness of the coating film layers.