Effect of Fe on the Microstructure and Properties of the CuMnNiSn Compound

Abstract One of the current challenges in materials research for sustainable technologies is the development of efficient alternatives for clean energy generation. In this context, the recovery of low-grade thermal waste using thermomagnetic motors has gained increasing attention. A major limitation for the advancement of this technology is the availability of materials with suitable structural, magnetic, and corrosion properties. Accordingly, this study investigates two intermetallic compounds, CuMnNiSn and CuFe 0.4 Mn 0.8 Ni 0.8 Sn, with the aim of assessing their potential for application in thermomagnetic systems. The effects of the partial substitution of Mn and Ni by Fe were examined with respect to microstructure, corrosion behavior, and Curie temperature. The CuMnNiSn compound exhibited two phases with equivalent chemical compositions but distinct space groups, while CuFe 0.4 Mn 0.8 Ni 0.8 Sn presented an additional Fe-rich phase. Linear polarization tests indicated that CuMnNiSn displayed superior corrosion resistance compared to CuFe 0.4 Mn 0.8 Ni 0.8 Sn, with corrosion rate of 6.79 × 10 −3 and 0.910 mm year −1 , respectively. The Curie temperatures were approximately 360 K for CuMnNiSn, as well as 370 K and 990 K for CuFe 0.4 Mn 0.8 Ni 0.8 Sn. Hardness measurements confirmed that CuMnNiSn exhibited the lowest hardness among the evaluated compositions, reaching a value of 485 HV, while CuFe 0.4 Mn 0.8 Ni 0.8 Sn reached 609 HV. Graphical Abstract