INVESTIGATION OF PHASE-COMPOSITION AND REMANENCE ENHANCEMENT IN RAPIDLY QUENCHED ND-9(FE, CO)(85)B-6 ALLOYS

Melt-spun and annealed Nd-9(Fe1-xCox)(85)B-6 alloys with x=0-0.4 have been studied by means of X-ray diffraction, transmission electron micr oscopy, thermomagnetic analysis and magnetic measurements. Both quench ing of the alloys and crystallization of the amorphous phase are accom panied by the formation of a metastable phase of TbCu7 type. When 0 le ss than or equal to x less than or equal to 0.3, short-time annealing at about 680 degrees C results in coexistence of nanocrystalline excha nge coupled Nd-2(Fe,Co)(14)B and b.c.c. Fe-Co phases. Because of the s tabilizing effect of Co on the 1:7 phase, the annealing that is optima l with respect to the sizes of the alpha grains is found to be insuffi cient for complete disappearance of the 1:7 phase in Co substituted al loys.