The characteristics of magnetostructural coupling play a crucial role in the magnetic field-driven behaviour of magnetofunctional alloys. The availability of magnetostructural coupling over a broad temperature range is of great significance for scientific and technological purposes. This work demonstrates that strong magnetostrucural coupling can be achieved over a wide temperature range (222 to 355 K) in Co-doped high Mn-content Mn₅₀Ni_42−x Co _x Sn₈ (0 ≤ x ≤ 10) melt-spun ribbons. It is shown that, over a wide composition range with Co content from 3 to 9 at.%, the paramagnetic austenite first transforms into ferromagnetic austenite at T _C on cooling, then the ferromagnetic austenite further transforms into a weakly magnetic martensite at T _M. Such strong magnetostructural coupling enables the ribbons to exhibit field-induced inverse martensitic transformation behaviour and a large magnetocaloric effect. Under a field change of 5 T, a maximum magnetic entropy change ΔS _M of 18.6 J kg⁻¹ K⁻¹ and an effective refrigerant capacity RC _eff of up to 178 J kg⁻¹ can be achieved, which are comparable with or even superior to those of Ni-rich Ni–Mn-based polycrystalline bulk alloys. The combination of high performance and low cost makes Mn–Ni–Co–Sn ribbons of great interest as potential candidates for magnetic refrigeration.

The superelastic and elastocaloric properties of a Mn-rich Ni₄₄Mn₄₆Sn₁₀ polycrystalline alloy prepared by directional solidification were studied. Owing to the coarse columnar shaped grains with strong ⟨001⟩_A preferred orientation, a large superelastic strain up to 8% and a transformation strain of 5.6% can be obtained through compressive stress induced martensitic transformation. Moreover, a giant adiabatic temperature variation up to –18 K was achieved on removing the stress. Such a remarkable elastocaloric effect is attributed to the large transformation entropy change through composition modification and the enhanced mechanical properties due to the formation of a highly textured microstructure in the directionally solidified alloy.