Phase constitution, microstructure evolution and magnetocaloric properties of LaFe11.8Si1.2 strip-casting flakes

摘要

The phase composition, microstructural evolution and magnetocaloric properties of LaFe11.8S1.2 strip-casting flakes annealed at different temperatures and annealing times were investigated. The phase constitution and microstructure of strip-casting flakes are sensitive to annealing temperature, 1373K was found to be the optimum temperature for 1:13 phase formation. The microstructure and magnetocaloric properties changed with annealing time due to the diffusion of Fe and Si atoms. Samples annealed at 1373K for 10h reveal a high content (89.40 wt%) of the 1:13 phase and exhibited a maximum entropy change (-Delta S-M)(max) of 16.89J/(kg.K) at 187K. These annealed LaFe11.8S1.2 strip-casting flakes are ideal master alloys for powder metallurgy fabrication of the heat exchangers used inactive magnetic regenerator prototypes.

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