A high-coercivity alloy composition for permanent magnets is described, containing re 34-37, cu 2-7, mg 0.05-.40, and CO 55.6- 63.9 Wt pct, other than sm, where re is misch metal or a rare-earth element. Alloys containing both cu and mg had substantially higher coercivity. For example, an alloy containing misch metal 36, cu 6.0, Mg 0.21 Wt pct and the remainer CO had intrinsic coercivity 27.6 Koe, normal coercivity 6.05 Koe, remanence 6.26 Kg, and energy product 9.5 Mg-oe, respectively, versus values of 0.7 Koe, 0.67 Koe, 6.24 Kg, and 2.0 Mg-oe respectively, for an alloy containing 4.0 Wt pct cu and no mg.
U.S. Pat. 4,174,966; Nov. 20, 1979; Chem. Abstr. 91:101,192Y