Heusler alloy ${\mathrm{Mn}}_{50}{\mathrm{Ni}}_{40}{\mathrm{In}}_{10}$ was produced as preferentially textured ribbon flakes by melt spinning, finding the existence of martensitic-austenic transformation with both phases exhibiting ferromagnetic ordering. A microcrystalline three-layered microstructure of ordered columnar grains grown perpendicularly to ribbon plane was formed between two thin layers of smaller grains. The characteristic temperatures of the martensitic transformation were $M_S=213\mathrm{K}$ , $M_f=173\mathrm{K}$ , $A_S=222\mathrm{K}$ , and $A_f=243\mathrm{K}$ . Austenite phase shows a cubic $L{2}_1$ structure ($a=0.6013\left(3\right)\mathrm{nm}$ at $298\mathrm{K}$ and a Curie point of $311\mathrm{K}$ ), transforming into a modulated fourteen-layer modulation monoclinic martensite.

We determined the magnetic entropy change and refrigerant capacity of melt spun ${\mathrm{Ni}}_{50.3}{\mathrm{Mn}}_{35.5}{\mathrm{Sn}}_{14.4}$ ribbons around both the structural and the magnetic transitions for a field of $20\mathrm{kOe}$ . The maximum entropy changes at the structural and magnetic transitions were of 4.1 and $-1.1\mathrm{J}{\mathrm{kg}}^{-1}{\mathrm{K}}^{-1}$ . Ribbons studied show a larger refrigerant capacity around the magnetic transition $\left(46\mathrm{J}{\mathrm{kg}}^{-1}\right)$ than around the structural transition $\left(26\mathrm{J}{\mathrm{kg}}^{-1}\right)$ , suggesting that the temperature range at the magnetic transition is more adequate for a refrigerant cycle than that at the structural transition.

The Heusler alloy ${\mathrm{Ni}}_{50}{\mathrm{Mn}}_{37}{\mathrm{Sn}}_{13}$ was successfully produced as ribbon flakes of thickness around $7–10\mu \mathrm{m}$ melt spinning. Fracture cross section micrographs in the ribbon show the formation of a microcrystalline columnarlike microstructure, with their longer axes perpendicular to the ribbon plane. Phase transition temperatures of the martensite-austenite transformation were found to be $M_S=218\mathrm{K}$ , $M_f=207\mathrm{K}$ , $A_S=224\mathrm{K}$ , and $A_f=232\mathrm{K}$ ; the thermal hysteresis of the transformation is $15\mathrm{K}$ . Ferromagnetic $L{2}_1$ bcc austenite phase shows a Curie point of $313\mathrm{K}$ , with cell parameter $a=0.5971\left(5\right)\mathrm{nm}$ at $298\mathrm{K}$ , transforming into a modulated $7M$ orthorhombic martensite with $a=0.6121\left(7\right)\mathrm{nm}$ , $b=0.6058\left(8\right)\mathrm{nm}$ , and $c=0.5660\left(2\right)\mathrm{nm}$ , at $150\mathrm{K}$ .

Thermal and field-induced martensite-austenite transition was studied in melt spun ${\mathrm{Ni}}_{50.3}{\mathrm{Mn}}_{35.3}{\mathrm{Sn}}_{14.4}$ ribbons. Its distinct highly ordered columnarlike microstructure normal to ribbon plane allows the direct observation of critical fields at which field-induced and highly hysteretic reverse transformation starts ($H=17\mathrm{kOe}$ at $240\mathrm{K}$ ), and easy magnetization direction for austenite and martensite phases with respect to the rolling direction. Single phase $L{2}_1$ bcc austenite with $T_C$ of $313\mathrm{K}$ transforms into a $7M$ orthorhombic martensite with thermal hysteresis of $21\mathrm{K}$ and transformation temperatures of $M_S=226\mathrm{K}$ , $M_f=218\mathrm{K}$ , $A_S=237\mathrm{K}$ , and $A_f=244\mathrm{K}$ .