Nanostructured (Sm,Pr)(Co,Zr) magnets with the TbCu 7-type structure have been synthesized by mechanically milling (Sm 1-xPr x) 12.5Co 85.5Zr 2 alloys (0≤x≤0.8) followed by appropriate annealing. Magnetic properties, structure, and microstructure have been investigated. It is found that single-phase (Sm,Pr)(Co,Zr) 7 magnets with the TbCu 7 structure and with nanoscale grain size (14-19 nm) form in the whole composition range. Intrinsic coercivity H ci decreases from 20.7 to 5.6 kOe with increasing Pr content from 0 to 0.8, while energy products (BH) max shows an optimum value of 12.6 MGOe (H ci of 17.9 kOe) at x=0.2 due to increase in remanent magnetization. Remanence ratio is observed in the range of 0.64-0.69, with an optimum value of ∼0.69 at x=0.3. The high coercivity is ascribed to the formation of nanocrystalline (Sm,Pr)(Co,Zr) 7 phase of the TbCu 7-type structure with large anisotropy, and the remanence enhancement may result from the exchange-coupling interactions between nanosized (Sm,Pr)(Co,Zr) 7 grains. The magnetic properties can be understood in term of the anisotropy of the magnetically hard phase and the interactions between the nanosized grains.
ASJC Scopus subject areas
- Physics and Astronomy(all)