An Investigation of the Mechanical, Thermal and Electrical Properties of an AA7075 Alloy Reinforced with Hybrid Ceramic Nanoparticles Using Friction Stir Processing

Abstract

Aluminum AA7075, graphene nanoplates (GNP), boron nitride (BN), and vanadium carbide (VC) are used to fabricate hybrid nanocomposite matrices. BN and VC serve as secondary reinforcement particles in the fabrication of hybrid composites, with graphene (GNP) as a key component of the hybrid process. Friction stir processing (FSP) was used to manufacture the composite matrix; it also has a major role in improving the microstructure’s grain refinement, as well as the reinforcing of the particles, which play a crucial role in limiting grain growth during the dynamic recrystallization process. Consequently, the grain sizes of the nanocomposite AA7075/GNPs, hybrid composites AA7075/GNPs+BN, and hybrid composites AA7075/GNPs+BN+VC were decreased by an average of 10.3 times compared to the base alloy. The SEM analysis demonstrated that the dispersion of the hybrid reinforcement particles was performed, and the particles were dispersed uniformly throughout the metal matrix. The mechanical characteristics of the hybrid AA7075/GNPs+BN+VC include the highest compression stress and hardness values due to the homogeneity of the hybridization process between the BN and VC particles. The GNPs reduce the electrical conductivity by 7.3% less than the base alloy. In comparison, when hybridized with BN and VC, it is reduced by 24.4% and 31.1%, respectively. In addition, the inclusion of thermally insulating materials, such as BN and VC, decreases the thermal conductivity of the hybrid composite metal matrices.