The R-Fe-B (R, rare earth) sintered magnets prepared with different ratio of alloys of MM-Fe-B (MM, misch-metal) and Nd-Fe-B by dual alloy method were investigated. As expected, the high ratio of MM-Fe-B alloy degrades the hard magnetic properties heavily with intrinsic coercivity lower than 5 kOe. When the atomic ratio MM/R ≤ 21.5% the magnetic properties can reach a practical level of Br ≥ 12.1 kGs, Hcj ≥ 10.7 kOe, and (BH)max ≥ 34.0 MGOe. And the effect of Hcj enhancement by the grain boundary diffusion process is obvious when MM/R ≤ 21.5%. It is revealed that the decrement of intrinsic magnetic properties of R2Fe14B matrix phase is not the main reason of the degradation of the magnets with high MM ratio. The change of deteriorated microstructure together with phase component plays fundamental roles in low Hcj. In high MM ratio magnets, (a) after annealing, Ce atoms inside main phase are inclined to be segregated in the outer layer of the main phase grains; (b) there is no thin layer of Ce-rich phase as an analogue of Nd-rich phase to separate main phase grains; (c) excessive Ce tends to form CeFe2 grains.

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Bonded La(Fe, Si)13 magnetic refrigeration materials have been prepared, and the microstructure, mechanical properties, and magnetocaloric effect (MCE) of bonded LaFe11.7Si1.3C0.2Hx have been investigated systematically. Bonded materials show porous architecture, and the mechanical properties increase with the increase of epoxy resin content, which could fill more pores and boundaries and thus enhance the binding force between different particles. Bonded LaFe11.7Si1.3C0.2H1.8 with 3 wt. % epoxy resin exhibits a compressive strength of 162 MPa, 35% higher than that of bulk compound. The mass magnetic entropy change (ΔSM) remains nearly unchanged while the volumetric ΔSM reduces due to the decrease of density in bonded materials. For a low magnetic field change of 2 T, the maximum ΔSM value of bonded LaFe11.7Si1.3C0.2H1.8 is ∼10.2 J/kg K and ∼54.7 mJ/cm3 K, which is larger than those of some magnetocaloric materials in the same temperature range. Enhanced mechanical properties and great MCE suggest that bonded La(Fe, Si)13-based materials could be promising candidates of magnetocaloric materials for practical applications of magnetic refrigeration.