Microstructure and magnetocaloric behavior of melt-extracted La(Fe_xSi_1–x)₁₃ microwires subjected to short-time annealing

La-Fe-Si-based magnetic refrigeration materials have attracted considerable attention for room-temperature magnetic cooling due to their large magnetic entropy change, low cost, and tunable Curie temperature. However, conventional La(Fe,Si)₁₃-based alloys typically require prolonged annealing lasting several days, significantly limiting production efficiency. In this study, La_1.12Fe_11.6Si_1.4 microwires were successfully fabricated by melt extraction, meeting the requirement for short-duration annealing. The structure, phase composition, and magnetocaloric effect of microwires subjected to different annealing durations (0 h, 5 h, and 10 h) were systematically investigated. The as-extracted microwires exhibited a crystallinity of approximately 30%, primarily consisting of LaFeSi and α-Fe phases, with fine dendritic α-Fe grains embedded within the LaFeSi matrix. After 5 h of annealing, the fraction of magnetic phases increased significantly to 60.7 wt%, and the magnetic phases showed a higher Si content. These microwires exhibited a Curie temperature of 209.8 K and the maximum magnetic entropy change (−ΔS_M^max) of ∼8.71 J·kg⁻¹·K⁻¹ under a 5 T field. When the annealing time was extended to 10 h, the transition temperature increased to 215 K, while the maximum magnetic entropy change slightly decreased to ∼8.46 J·kg⁻¹·K⁻¹. Normalized entropy change curves and critical exponent n analysis indicate predominantly second order magnetic transition behavior. This work demonstrates that melt-extracted microwires can achieve a moderate magnetocaloric response after a reduced annealing duration, providing a material form with potential advantages in heat exchange and regenerator geometry.