Improvement in magnetocaloric, mechanical and corrosion properties of La1.4Fe11Co0.8Si1.2 bulk composites prepared by hot-deformation and diffusion annealing

Abstract

La-Fe-Si alloys are of high interest for near room temperature magnetocaloric applications. La_1.4Fe₁₁Co_0.8Si_1.2 magnetocaloric composites were prepared by hot-deformation and diffusion annealing to improve the kinetics of the formation rate of the desired 1:13 phase and reduce its brittleness. The effects of La_1.4Fe₁₁Co_0.8Si_1.2 particle size on the formation of 1:13 phase, as well as the magnetocaloric, mechanical and corrosion properties were investigated. The results showed that the process deployed in this work shortened the annealing time and promoted the formation of 1:13 phase. The initial particle size influenced phase formation during diffusion annealing. For smaller particle size, the 1:13 phase content and microstructural homogeneity were enhanced after annealing. The diffusion distance between the La-rich phase and the α-Fe phase decreased. Significantly, the bulk composites exhibited a large magnetic entropy change (5.6–6.1 J·kg⁻¹·K⁻¹, μ₀ΔH = 2 T) and high refrigeration cooling power (128.7–142.1 J·kg⁻¹) near room temperature owing to its high 1:13 phase content. These composites also had large bending strength and good corrosion resistance. Thus, this processing technology was demonstrated to be a facile method to fabricate magnetocaloric composites with excellent near room temperature performance.