Rapid phase formation and magnetocaloric properties of off-stoichiometric LaCe_0.3Fe₁₁Co_0.8Si_1.2 strip-casting flakes

The rapid phase formation and magnetocaloric properties of LaCe_0.3Fe₁₁Co_0.8Si_1.2 strip-casting flakes annealed at 1373 K for durations varying from 2 min to 24 h were investigated. The rare earth elements refined the microstructure into a fine lamellar structure, which promoted the formation of the NaZn₁₃-type structure (1:13) phase. Consequently, a high 1:13 phase content of 88.5 wt% was obtained within only 5 min at 1373 K. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) fitting results revealed that the rapid formation of the 1:13 phase resulted from the thickening of large lamellar precipitates. After annealing for 6 h, the maximum 1:13 phase content of 95.6 wt% was obtained, along with a maximum magnetic entropy change (−ΔS_M)^max of 10.6 J·kg⁻¹·K⁻¹ and a relative cooling power (RCP) of 151.6 J·kg⁻¹ (Δμ₀H = 2 T). The large (−ΔS_M)^max and RCP values, as well as short annealing time, make these alloys promising candidates as magnetic refrigerants for near room temperature applications.