Magnetostructural transition behavior in Fe-doped Heusler Mn–Ni–In ribbon materials

• The magnetostructural transition behavior of Fe-doped Mn–Ni–In was investigated.
• Substituting Mn with Fe would lead to striking grain refinement in melt-spun Mn–Ni–In ribbon materials.
• Secondary phase formed when 2 at% Mn was replaced by Fe in annealed Mn–Ni–In ribbon materials.

In the present work, we investigated magnetostructural transition behavior in Mn-rich Heusler Mn50−xFexNi41In9 (x=0, 1, 2, 3 at%) ribbon materials. Microstructural observations showed that substituting Mn with Fe in Mn50Ni41In9 led to striking grain refinement from ∼50 μm to 5–10 μm, and formation of a secondary phase when Fe content was increased up to 2 at%. Differential scanning calorimetric and thermomagnetic measurements indicated that a paramagnetic→ferromagnetic transition in austenite occurred first, followed with a weak-magnetic martensitic transition upon cooling for the Mn50−xFexNi41In9 (x=0, 1, 2). In case of Mn47Fe3Ni41In9, the martensitic transformation happened between paramagnetic austenite and weak-magnetic martensite, without the presence of the magnetic transition in austenite. The effective refrigeration capacity of Mn49Fe1Ni41In9 reached 137.1 J kg−1 under a magnetic field change of 30 kOe.