Effect of hot deformation on texture and magnetic properties of Sm–Co and Pr–Co alloys

Nanocrystalline PrCo5, SmCo5 and Sm2(Co,Fe,Mn)17 alloys were subjected to a high-degree plastic deformation at 950 °C with the height reduction ranging from 70% to 95%. With increasing degree of deformation, the PrCo5 and SmCo5 magnets showed improvement of the deformation-induced [0 0 1] texture. The PrCo5 alloys, known to develop a superior texture at the lower degrees of deformation, showed only modest improvement and their magnetic performance was undermined by a low coercivity. The SmCo5 alloys had their texture markedly enhanced and, after height reduction by 94.5%, they exhibited a remanence of 8.6 kG, maximum energy product of 18 MGOe and an intrinsic coercivity of 22.8 kOe. No induced texture was found in the alloys based on the Sm2Co17 structure. The microstructures of the hot-deformed alloys were studied with a transmission electron microscopy, and possible mechanisms of the texture development in the RCo5 alloys (R=Pr, Sm) are briefly discussed.

► The effects high-degree deformation were compared for three rare earth–cobalt alloys. ► SmCo5 alloys benefit most from deformation exceeding 90%. ► High-degree deformation slightly improves texture of PrCo5 but damages the coercivity. ► Even the high-degree deformation does not induce texture in alloys based on Sm2Co17.