Thermal and wear properties of Al/Cu functionally graded metal matrix composite produced by severe plastic deformation method

Abstract

The past decade has witnessed a huge growth in functionally graded materials (FGM) with attractive properties. This paper is a preliminary attempt to investigate Al/Cu FGM produced by a new methodology consisting of cold roll bonding (CRB) and accumulative roll bonding (ARB) processes. The results of microstructural characterizations reveal that the volume fraction of copper changed gently across the FGM. The observed distribution of copper's pieces was achieved by using the ARB process in which the reinforcement can be well distributed in the matrix. The findings of tensile tests revealed that, with an increase in Cu content, the ultimate tensile strength of layers increased while the elongation decreased. Also, the elongation of FGMMC which was about 4.6 was the least value and its tensile strength which was around 367 MPa was as much as that of Al/80%Cu but less than that of Cu layer. The results of wear tests showed that as the volume fraction of the reinforcement rose, friction coefficient and volumetric worn loss declined; indeed, hard copper layers can be plastically deformed as much as aluminum. Then, a smaller amount of material was abraded during pin on disk interaction. Based on the results of thermal diffusivity, with an increase in copper content, the thermal conductivity increased from Al layer with 155.5 W/mK to Cu layer with 283.3 W/mK indicating the good conductance of the Al/Cu interface and copper's pieces. Further, the thermal conductivity of FGMMC with 201.67 W/mK was more than all laminated composites except Cu layer.