MAGNETIC-PROPERTIES AND MICROSTRUCTURAL CHARACTERIZATION OF SINTERED PR16FE76-X-YCOXALYB8 (0-LESS-THAN-X-LESS-THAN-20, 0-LESS-THAN-Y-LESS-THAN-8) MAGNETS

A number of Pr16Fe76-x-yCoxAlyB8 (0 < x < 20; 0 < y < 8) magnets are p repared by conventional powder metallurgy processes. Magnetic measurem ents indicate that the magnet coercivity (H-1(c)) increases as y incre ases up to about 3 and decreases as x and y increase up to 20 and > 3, respectively. The remanence (B-r) decreases with increasing of x and y concentrations. When x and y are added at the same time, H-1(c) and B-r are mainly determined by the x and y concentrations. The microstru cture and the chemical composition of the phase structure are also det ermined for the cast and sintered alloys. The good magnetic properties are attributed to grain size and improved magnetic isolation of the i ndividual grains, which is promoted by addition of Al up to 3 at %. In particular, this is apparent in magnets with Co additions (Co additio ns cause grain growth during the sintering process).