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Ni45.6Fe3.6Mn38.4Sn12.4 microwires, with nanoscale γ-phase precipitates that enhance the magnetocaloric effects (MCEs) and mechanical properties, were prepared by a melt-extraction technique and subsequent high temperature annealing. The atomic ordering degree significantly increased after annealing, leading to a considerable increment in the structural entropy change (ΔStr) from 4.5 J/kg·K in the as-extracted microwire to 26.6 J/kg·K in the annealed one, and the magnetization difference (ΔM) from 35 A·m2/kg to 51 A·m2/kg under a magnetic field of 5.0 T. Consequently, a positive magnetic entropy change (ΔSM) peak of 15.2 J/kg·K with working temperature span (ΔTFWHM) of 12 K for the first-order martensite transformation followed by a negative ΔSM peak of −4.3 J/kg·K with ΔTFWHM = 50 K for the second-order magnetic transition under μ0ΔH = 5.0 T was achieved. By employing both magnetizing and demagnetizing processes for magnetic cooling, the two successive inverse and conventional MCEs in Ni–Fe–Mn–Sn microwires may show potential applications for micro-devices and systems. [ABSTRACT FROM AUTHOR]

• Ni 40.7 Mn 42.9 Sn 10.4 Co 6.0 foam with porosity 56% was created by replication casting and annealing. • The foam had reduced thermal hysteresis (9.0 K). • The foam showed entropy change 4.7 J/kg·K with working temperature span 40 K under 5.0 T. • The foam exhibited a small hysteresis loss (AHL) 17.4 J/kg under 5.0 T. • The foam produced refrigeration capacity 155 J/kg and relative cooling power 188 J/kg. Enhanced magnetic refrigeration performance via introducing pores in a ferromagnetic shape memory Ni-Mn-Sn-Co alloy was demonstrated. The Ni 40.7 Mn 42.9 Sn 10.4 Co 6.0 foam, with a porosity of 56% created by replication casting technique, exhibited reduced thermal hysteresis because of the high specific surface area. A maximum magnetic entropy change (Δ S M) 4.7 J/kg·K with a very wide working temperature span (Δ T FWHM) 40 K under 5.0 T were found in the annealed foam. Furthermore, the foam showed a small hysteresis loss (AHL) 17.4 J/kg under 5.0 T. As a result, refrigeration capacity (RC) 155 J/kg and relative cooling power (RCP) 188 J/kg were produced. [ABSTRACT FROM AUTHOR]