MAGNETIC AND STRUCTURAL-PROPERTIES OF HIGH REMANENCE ND-8(FECO)(88)B-4 PREPARED BY MECHANICAL MILLING

The effect of Co substitution for Fe on the structure and magnetic pro perties of mechanically milled Nd8Fe88B4 has been investigated. As-mil led Nd-8(Fe1-xCox)(88)B-4 (x=0-0.6) alloys exhibited a two-phase mixtu re consisting of an amorphous phase and a bcc FeCo phase. Optimal anne aling of the as-milled samples led to the formation of a nanocrystalli ne mixture of Nd-2(FeCo)(14)B and a bcc FeCo phase. The optimally anne aled samples exhibited single-phase magnetic behavior and remanence en hancement. Replacement of up to 20% of Fe by Co increased both remanen ce and coercivity. Over substitution of Co and heat treatment at tempe ratures exceeding 600 degrees C caused the deterioration of both reman ence and coercivity. (C) 1997 American Institute of Physics. [S0021-89 79(97)00921-3].