Coercivity kinetics upon step annealing of sintered Sm(Co_0.88-xFe_xCu_0.09Zr_0.03)₇ magnets

A.G.Popov^1,2，O.A.Golovnia^1,2，A.V.Protasov^1,2，V.S.Gaviko^1,2，D.A.Kolodkin¹

1. M.N.Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences2. Institute of Natural Sciences and Mathematics, Ural Federal University

摘 要：Behavior of the coercivity of the high-temperature Sm(Co_0.88-xFe_xCu_0.09Zr_0.03)₇ magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo₅ phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm₂ Co₁₇ and SmCo₅ phases.Diffusive enrichment of the SmCo₅ phase in Cu close to the interface with Sm₂ Co₁₇ leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.

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