Processing and Characterisation of Functionally Graded Materials Based on Few-Layered Graphene Reinforced Aluminum

Abstract

Functionally graded materials (FGMs) are advanced engineering materials developed due to their superior properties where traditional composite materials are not sufficient. Nowadays, the development and application of these materials for the potential areas have attracted much more attention. Aluminum (Al) is preferred for physical and mechanical properties such as lightweight, high specific strength, high specific modulus, and low thermal expansion coefficient in these potential applications. Graphene attracts great attention worldwide due to its superior mechanical, electrical and thermal properties. In the current study, fewlayered graphene (FLG) produced with high purity electric arc discharge method were used to reinforce the Al matrix using various (in wt%) of 0, 0.1, 0.2, 0.3, 0.5, and 0.7 FLG by mechanically alloying (MA). Composite powders were consolidated by cold pressing with a layer by layer under 450 MPa. Al-FGM composites were designed including six layers and they were subjected to sintering at approximately 590 °C under argon atmosphere. The microstructure of Al-FGM was investigated by optical microscopy and scanning electron microscopy (SEM). It was observed that the FLG placed between the grains and acts as a barrier through the gradation improving the mechanical properties of the Al-FGM. Hardness value of the layer with the highest graphene content was measured as 113 HV. An increase in the Vickers hardness by 18% was observed in the last layer with FLG content of 0.7 wt% compared to the first layer.