The tuning of Heusler alloys with respect to the stoichiometry and their effect on martensitic transformation have been investigated very little by various researchers. Thus, the effect of change in ferrous (Fe) concentration of the alloys and its effect on mechanical and magnetocaloric properties of Ni 50-x Fe x Mn 30 Sn 20-y In y alloys were investigated where Fe was varied from x= 1, 2, 3 and 4 to find its significance. An increase of Fe concentration to Fe 4 leads to a considerable improvement in the alloy's mechanical properties and crystal structure. Compressive strength of the alloy rose by 123% for Fe 4 substitution. When comparing the identical materials with and without Fe addition, the ultimate stress (US) and ductility are improved by 124 and 200%, respectively, while toughness rises by 48 times. The Fe concentration variation also enabled a martensitic transformation in 36.8 to 19.83 °C range of refrigerator applications.

The magnetic and electrical characteristics of Ni-Mn quinary Heusler alloys are studied in the current work. The results concern the materials’ magnetic and electrical behavior. The physical property measurement system (PPMS) and superconducting quantum interference device (SQUID) were used at various magnetization levels to determine the results. The addition of Fe helps to form the alloy into a smart memory alloy with magnetocrystalline anisotropy, twin border mobility, and varied magnetic and martensite transition temperature characteristics. Character changes in the superparamagnetic (SPM) and paramagnetic (PM) alloys occur between 26 and 34 °C. The curves are supported by the alloy’s martensitic transition temperature change. A large refrigeration capacity is identified in the alloy. These properties are an indication of the alloys’ application prospects. Entropy change helps to detect the inverse magnetocaloric effect in the alloy, whereas adiabatic temperature change helps identify the origin and validity of reverse magnetic properties. The transition temperature changes occur when austenite’s sigma is larger than that of martensite, and as the magnetic field increases, the temperature declines. Isothermal magnetization curves, a large (MR)/B value at low and high magnetic fields, and temperatures near the transformation point suggest that small-crystal Heusler alloys have tremendous promise for low and high magnetic field magnetoresistance applications.

Ni-Mn-based quinary Heusler alloys have seldom been investigated with respect to their martensitic transformation and mechanical properties for near room temperature transformation. In the current work, we identified and investigated martensitic transformation near room temperature, and the martensitic properties of Ni-Mn-Sn-Fe-In-based quinary Heusler alloys. Alloys prepared in an argon-rich vacuum arc melting furnace. During X-ray diffraction (XRD) analysis, it was identified that the L21 cubic structure austenite phase of the alloy transforms into L10 orthorhombic martensite phase in the case of alloys with greater Fe substitution. The martensitic transformation zone of the alloy is also shifted to the near-room-temperature range of 15–28 °C by changing the stoichiometry of the alloy composition. Magnetic measurements like field heating (FH), field cooling (FC) and zero field cooling (ZFC) indicate the presence of a dual magnetic phase in the alloy, while magnetic susceptibility testing also helped to establish claims regarding the magnetic measurement results.

Ni-Mn based heusler alloy with Ni50-xFexMn30Sn20-yIny where 1<=x<=4; 2<=y<=8 are studied for their structural as well as mechanical characteristics using various testing facility such as field emission scanning electron microscope, energy dispersion spectrometry, differential scanning calorimetry and Vickers hardness equipment. From the general understanding the materials are to display a transformation of austenite-martensite. The materials are seen to be showing this transformation in and around near room temperature. The optical and FESEM imaging of the specimen show that during annealing heating to high temperature to longer time, the diffusion kinetics are activated at faster rate so that the dendritically structure is annihilated to develop well distributed grain structure. The coarser dendrites seems to be broken and fine grain, well dispersed phases are formed. X-ray diffraction confirms the peak split and martensitic transformation in the system of alloys. DSC results confirm the martensitic transformation around room temperature.

Present work is on Heusler alloys of the sequence Ni50–xFexMn30Sn20–yIny, were prepared in order to investigate the relationship between microstructure and mechanical property. The work represents the variations in the hardness of the alloy when the component elements are changed. Alloys show Vickers hardness HV = 3.5 GPa at x = 2 and y = 4. At x = 4 and y = 8, alloy exhibits an L10 tetragonal structure, whereas at x = 3 and y = 6 L21 austenite phase structure is observed. Interface piling up occurs which greatly reduces fracture propagation and dislocation at neighboring interfaces. Large piled-up interfaces available in the martensite phase due to the sub-strips significantly contribute this process resulting in large hardness value. In spite of thicker laminates in the austenite phase, the alloy exhibits higher hardness than martensite phase or even the composite. Hardness is particularly low in the martensitic phase (x = 4, y = 8), which is produced owing to interfacial motion. The hardness value falls as the Sn concentration increases due to weak pinning between the strips. A drastic increase in hardness of 3.5 GPa has been observed when x = 2 and y = 4.