Impact of partial substitution of Sn by Cu on the mechanical, electrical, and magnetic properties of Ni44Mn44Sn12 Heusler alloys

Impact of partial substitution of Sn by Cu on the mechanical, electrical, and magnetic properties of Ni₄₄Mn₄₄Sn₁₂ Heusler alloys was analyzed in this study. The alloys Ni₄₄Mn₄₄Sn₁₂, Ni₄₄Mn₄₄Sn_10.5Cu_1.5, and Ni₄₄Mn₄₄Sn₉Cu₃ were produced through casting without atmosphere control and characterized using microscopy scanning electron microscopy, X-ray diffraction, Vickers microhardness tests, electrical resistivity measurements, and vibrating sample magnetometry. The results showed that the partial substitution of Sn with Cu did not affect the solidification microstructure or the phases present at room temperature. However, this substitution increased the transition temperatures from austenite to martensite and from martensite to austenite, increasing the proportion of the martensitic phase from 56.04 to 77.67%. This resulted in a decrease in Vickers microhardness (from 468.3 to 352.3 HV), electrical resistivity (from 1.3 to 1.16 mΩ∙mm), and saturation magnetization (from 23.67 to 9.6 emu/g). In contrast, both coercivity and remanent magnetization rose, with values changing from 5.37 to 21.64 Oe and from 0.16 to 0.31 emu/g, respectively. Thus, our findings present a new approach for doping the NiMnSn alloy, aimed at modifying its structural and electrical properties, which are important factors for technological applications.