Precipitation hardened magnets

Sm-Co anisotropic powders have been developed to prepare magnets meeting high operating temperature requirements [135]. These powders are produced by pulverization of bulk ingots which have been submitted to the precipitation hardening heat treatment. 

The R-Co magnetic alloy is now usually a precipitation-hardened 2—17 type. In some cases, SmCo5 or (Sm, MM)C< powders are used, alone or in combination with 2-17 alloy powder. 

Dah] Dahl, O., Pfaffenberger, J., Magnetic Properties of Laminated Ion-Nickel Alloys after Precipitation Hardening (in German), Metall-Wirtschaft., 13, 527-532 (1934) (Experimental, Magn. Prop., Electr. Prop., Meehan. Prop., 15)... 

Common examples of magnetically hard materials are high carbon steels, precipitation hardened alloys e.g., Alnico), and sintered or bonded fine-particle alloys e.g., ferrites, rare earth alloys). The earliest examples of rare earth magnets are SmCos and Sm2Coi7, with recent developments focused on the incorporation of Fe rather than other costly transition metals. Whereas iron-rare earth alloys such as R2Fei7 have... 

Fig. 17. Example of the precipitation microstructures found in 1-5 type RE-Co magnets bulk-hardened with copper SmCo35Cu10Feo5 homogenized at 1100°C/3 h and quenched. Left SEM image after aging at 575°C/4 h. Right Light micrograph after additional aging at 525°C/4 h. The precipitates are...

Fig. 18. Example of the precipitation microstructure found in bulk-hardened 2-17 magnets of the high-Wc type Sm(Co0 67Fe0 23Cufl fl8Zrc,02)R.M fully heat treated to MHC = 23 kOe. Left section containing the c-axis note the rhomboid cells of the twinned 2-17 matrix, the 1-5 boundary phase surrounding the cells, and the thin bands of z-phase in the base plane, crossing many cells and walls. Right basal...

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