Improved mechanical properties of Cu8Ni4Sn alloy as functionally graded composites with preserving its thermal and electrical properties

Abstract

The main objective of this work was to improve the mechanical properties of a copper alloy, i.e., 88Cu–8Ni–4Sn (wt.%), without causing a significant reduction in its outstanding electrical and thermal conductivity. Based on this concept, the Ti3AlC2 MAX phase was prepared and added to Cu alloy in order to prepare five-layer functionally graded composites (FGCs) that fulfill this purpose using the powder metallurgy technique. The bottom layer of the FGCs consisted of Cu alloy, while the other layers were formed by adding the MAX phase in different proportions. Then, the milled powders were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). In addition, the mechanical, thermal, and electrical properties of the FGCs layers were investigated. The result showed that the milling process led to intermetallic phases (Ni3Sn and Cu3Sn), which contributed to the Ti3AlC2 phase, reducing the particle's size up to 44 nm (the top layer). Also, the top layer of FGC had a marked improvement in ultimate strength and microhardness, and Young's modulus scored 40, 72.1, and 26.1%, respectively, compared to the bottom layer. Fortunately, despite this amazing improvement in mechanical properties, the thermal and electrical properties reduction of the top layer of FGCs was slight. From the results, it can be concluded that the fabrication of FGCs is the optimal solution to improve the various properties of Cu alloy without sacrificing their other astonishing properties so that they can be used in various applications including spot welding electrodes, high performance electrical switches, anticorrosive coatings, and others.