Find in Library

A one-step sintering process was developed to produce magnetocaloric La(Fe,Si)₁₃/Ce-Co composites. The effects of Ce₂Co₇ content and sintering time on the relevant phase transformations were determined. Following sintering at 1373 K/30 MPa for 1–6 h, the NaZn₁₃-type (La,Ce)(Fe,Co,Si)₁₃ phase formed, the mass fraction of α-Fe phase reduced and the CeFe₇-type (La,Ce)(Fe,Co,Si)₇ phase appeared. The mass fraction of the (La,Ce)(Fe,Co,Si)₇ phase increased, and the α-Fe phase content decreased with increasing Ce₂Co₇ content. However, the mass fraction of the (La,Ce)(Fe,Co,Si)₇ phase reduced with increasing sintering time. The EDS results showed a difference in concentration between Co and Ce at the interphase boundary between the 1:13 phase and the 1:7 phase, indicating that the diffusion mode of Ce is reaction diffusion, while that of Co is the usual vacancy mechanism. Interestingly, almost 100 % single phase (La,Ce)(Fe,Co,Si)₁₃ was obtained by appropriate Ce₂Co₇ addition. After 6 h sintering at 1373 K, the Ce and Co content in the (La,Ce)(Fe,Co,Si)₁₃ phase increased for larger Ce₂Co₇ content. Therefore, the Curie temperature increased from 212 K (binder-free sample) to 331 K (15 wt.% Ce₂Co₇ sample). The maximum magnetic entropy change (−ΔS_M)^max decreased from 8.8 (binder-free sample) to 6.0 J/kg·K (15 wt.% Ce₂Co₇ sample) under 5 T field. High values of compressive strength (σ_bc)^max of up to 450 MPa and high thermal conductivity (λ) of up to 7.5 W/m·K were obtained. A feasible route to produce high quality La(Fe,Si)₁₃ based magnetocaloric composites with large MCE, good mechanical properties, attractive thermal conductivity and tunable <i>T</i>_C by a one-step sintering process has been demonstrated.