Zr-Rich Phases in Sm(CoFeCuZr)z Magnets

Sm(CoFeCuZr)z commercial magnets are manufactured by powder metallurgy techniques. Microstructural investigations of Sm(CoFeCuZr)z magnets have shown that, increasing the Zr content, some impurity phases may appear. An alloy with composition (at%): 60.5% Co – 15.5% Fe – 11.5% Zr - 8.5% Sm - 4% Cu, homogenized at 1050oC, was investigated. Three main phases were identified: rhombohedral 1:3 (ZrSm)1(CoFeCu)3, hexagonal 1:7 (SmZr)1(CoFeCu)7 and cubic 6:23 (Zr)6(CoFe)23. Knowledge of possible phases present in 2:17-type magnets allows a better understanding of the nanocrystalline microstructure responsible for high coercivity of these magnets.