Estudo das propriedades mecânicas, térmicas e elétricas das ligas de Heusler de média entropia - CuMnAlSn

Abstract

Heusler alloys were discovered in 1903 and are intermetallic compounds that are traditionally composed of three elements with X2YZ stoichiometry and that present ferromagnetic properties although none of the constituent elements is individually ferromagnetic. They have aroused great interest due to their structural and functional versatility, in addition to characteristics such as magnetocaloric effect, magnetic shape memory, magnetoresistance, and exchange bias. Several studies have been developed and demonstrated that the addition of a fourth element to Heusler alloys is a powerful tool to increase the versatility of Heusler alloys through the manipulation of their structure and properties. This work investigated Cu50Mn25Al25-xSnx alloys, exploring how the partial replacement of Al by Sn (x = 0, 5, 10, 15, and 20 at.%) influences their mechanical, thermal, electrical, and magnetic properties. The samples were prepared in an induction furnace at a temperature of 1300ºC without atmosphere control, melted in a graphite/clay crucible and poured into a metal mold, forming ingots with 110 mm in length and 12 mm in diameter. To study the samples, the CALPHAD method was combined with experimental characterization techniques such as Xray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometry (VSM) and Microhardness. The data obtained demonstrate that the partial replacement of Al by Sn alters the equilibrium between the phases, reduces the melting temperature, increases the microhardness and electrical resistivity, and reduces the remanent magnetization. The results of this work expand the knowledge about medium-entropy Heusler alloys, indicating that the modification of the structural, mechanical, thermal, electrical and magnetic properties of the Cu50Mn25Al25-xSnx alloy is strongly influenced by the Sn content, which can be used as a way to adjust the alloy properties, opening new perspectives for technological applications and contributing to the advancement in the area of Materials Science and Engineering.