Fabrication of functionally graded few-layered graphene reinforced Al-4.5Cu alloy by powder metallurgy

Abstract

Functionally graded materials (FGMs) are a class of innovative materials designed for needs that conventional composite materials cannot provide. Potential application areas such as aerospace, automobile, biomedical, defence, electrical/electronics, energy have begun to increase for the use of FGMs. Aluminium and aluminium alloys are preferred in these potential application areas for their physical and mechanical properties such as lightweight, high specific strength, high specific modulus and low thermal expansion coefficient. Graphene, one of the allotropes of carbon, is of great interest worldwide due to its superior mechanical, electrical and thermal properties. In this study, functionally graded graphene reinforced Al-4.5Cu alloy was produced by powder metallurgy. Few-layered graphene (FLG) with high purity, which was synthesized by the electric arc discharge (EAD) was reinforced to the Al-4.5Cu alloy powders that were produced by mechanical alloying as 0,0.1,0.2,0.3,0.5 and 0.7 wt%. These FLG reinforced Al-4.5Cu alloy composite powders considering FGM design with six layers, were pressed by stacking according to their various FLG contents and subjected to sintering at 570 °C and 590 °C for 3 h. It was observed that the FLG, which was graded according to their contents acting as a barrier between grains, was homogeneously dispersed in the Al-4.5Cu alloy matrix in optical and scanning electron images. According to the design of each FGM, an increase in the hardness by 37.11 % and 24.71 % was observed in the last layer compared to the first layer for sintering at 570 °C and 590 °C, respectively.