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

In the present work, we investigated magnetostructural transition behavior in Mn-rich Heusler Mn 50− x Fe x Ni 41 In 9 ( x =0, 1, 2, 3 at%) ribbon materials. Microstructural observations showed that substituting Mn with Fe in Mn 50 Ni 41 In 9 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 Mn 50− x Fe x Ni 41 In 9 ( x =0, 1, 2). In case of Mn 47 Fe 3 Ni 41 In 9 , 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 Mn 49 Fe 1 Ni 41 In 9 reached 137.1 J kg −1 under a magnetic field change of 30 kOe. [ABSTRACT FROM AUTHOR]