High density La-Fe-Si based magnetocaloric composites with excellent properties produced by spark plasma sintering

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Vol. 280; p. 115717
• Main Authors: Zhong, X.C., Wu, S.M., Dong, X.T., Li, Y.X., Huang, J.H., Liu, C.L., Zhang, H., Huang, Y.L., Yu, H.Y., Qiu, W.Q., Liu, Z.W., Zhong, M.L., Zhong, Z.C., Ramanujan, R.V.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-06-2022; Elsevier BV
• Subjects: Annealing; Cobalt; Composite materials; Compressive strength; Curie temperature; Density; Heat conductivity; Heat transfer; High density; Iron; La(Fe,Si)13 based composites; Magnetic properties; Magnetocaloric effect; Mechanical properties; Plasma sintering; Spark plasma sintering; Thermal conductivity; Spark plasma sintering; Annealing; La(Fe,Si)13 based composites; High density; Magnetocaloric effect
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2022.115717

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•High density La-Fe-Si based composites were fabricated by short time SPS followed by annealing.•The magnetocaloric and mechanical properties could be tuned by changing the SPS temperature.•The optimum process was SPS@1273 K/5min followed by annealing@1323 K/24 h.•Excellent (σbc)max ∼ 1GPa, λ ∼ 17.68 W/m∙K and large (−ΔSM)max ∼ 2.3 J/kg‧K@2T were obtained.
La(Fe,Si)13 based magnetocaloric composites were prepared by spark plasma sintering (SPS), followed by annealing. The microstructure, mechanical and magnetocaloric properties were investigated. With increasing SPS temperature (TSPS) below 1373 K, the content of (La,Pr)(Fe,Co,Si)13 majority phase increased, while the content of minority phase α-Fe decreased. The increase of TSPS from 973 K to 1373 K greatly improved the composite density, and the density sharply increased from ∼ 68 % to 98 %. After SPS at 1273 K/5 min followed by 1323 K/24 h annealing, high content of 89.35 wt% of the desired (La,Pr)(Fe,Co,Si)13 phase was obtained in LaFe11.6Si1.4/10wt%Pr2Co7 composites. A large increase of Curie temperature (TC) from 196 K to 297 K was observed. The maximum magnetic entropy change (−ΔSM)max reached 2.3 J/(kg‧K) under 2 T magnetic field. ∼ 97 % of full density, excellent compressive strength of ∼ 1GPa and high thermal conductivity of 17.68 W/m∙K were exhibited. Thus, a route to produce high density La-Fe-Si based magnetocaloric composites with excellent mechanical properties and thermal conductivity, good (−ΔSM)max and adjustable TC by short time spark plasma sintering followed by annealing was demonstrated.