Structure stability driven large magnetocaloric response in Ni–Co–Mn–In–Si Heusler alloy

Abstract

Ni–Mn–In Heusler alloys have received considerable attention in the field of magnetic refrigeration owing to their eco-friendliness and large magnetocaloric (MC) response. In this paper, samples of Ni45Co5Mn37In12Si1 thus heat-treated for 0 h and 15 h have prepared by means of arc-melting followed by quenching. X-ray diffraction analysis confirms L21-type crystal structure and stabilization of austenite phase at room temperature. FE-SEM equipped with EDS reveals the surface morphology and elemental composition of 15 h heat-treated Ni45Co5Mn37In12Si1 alloy with well-distinguished larger grains and a dendritic structure. Thermomagnetic measurements of 15 h heat-treated Ni45Co5Mn37In12Si1 shows the magnetostructural transition TCM at the temperature of ∼262 K and Curie temperature of austenite, TCA was found to be above ∼396 K with increase in the annealing time. Metamagnetic behavior and magnetic hysteresis are seen in isothermal magnetization curves. Interestingly, a large change in magnetic entropy ΔSM ∼9.3 J kg−1 K−1 was obtained with refrigeration capacity (RC) of ∼416.6 J kg−1 under an applied field change of 5T with a broad temperature window of ∼86 K for Ni45Co5Mn37In12Si1 alloy thus annealed for 15 h which makes it to be suitable for magnetic refrigeration applications.