Magnetic properties of substituted R/sub 2/(Fe,Al, Co)/sub 14/B compounds

The effects of the substitution of Fe by Al in R/sub 2/ (Fe/sub 1-x/Al/sub x/)/sub 14/B compounds (R = Y, rare earths) on their magnetic properties have been investigated. The compounds crystallize in the tetragonal structure, P4/sub 2//mnm, provided x < 0.1. The saturation magnetization and Curie temperatures decrease slightly with increasing Al content, x. However, the anisotropy constant, K/sub iota/, and the anisotropy field H/sub A/, exhibit a maximum at x = 0.06. The substitution of Fe with Al atoms is also effective in enhancing the coercivity of magnets based on the Nd-Fe-B compounds. As the Y atom carries no magnetic moment, the increased anisotropy field must result from preferential ordering of the non-magnetic Al atoms among the six non-equivalent crystallographic sites of the iron sublattice.