Improvement in the magnetocaloric properties of sintered La(Fe,Si)13 based composites processed by La-Co grain boundary diffusion

Abstract A novel method to combine hot pressing and grain boundary diffusion in order to fabricate La(Fe,Si) 13 based magnetocaloric composites is described. LaFe 11.6 Si 1.4 /La-Co magnetocaloric composites were prepared by hot-pressing, followed by diffusion annealing heat treatment. The Curie temperature ( T C ) of these composites increases from 197 K to ∼235 K due to the diffusion of Co into the NaZn 13 –type (1:13) majority phase. The maximum magnetic entropy change (– ΔS M ) max at 2 T first increases with increasing diffusion time from 5.62 to 7.60 J/(kgˑK) and followed by a further increase up to 9.15 J/(kgˑK) due to the recombination of the 1:13 phase. The Co content of the La-Co binder could be used to tune the formation of the desired 1:13 phase.