Friction stir additive manufacturing of B4C and graphene reinforced aluminum matrix hybrid nanocomposites using consumable pins

In this research, aluminum matrix hybrid nanocomposites reinforced with B4C and graphene nanoparticles were produced via friction stir additive manufacturing method. The appearance and macroscopic characteristics of the samples were investigated. The microstructural, mechanical, hardness, wear and corrosion behavior of the samples were investigated. During these investigations, it was found that after production, the microstructure of the samples changes compared to the consumable rod, and from the results of this transformation, we can mention the extreme grain fineness and distance of the precipitates in terms of number and size compared to the T6 heat treatment. It was also found that the nanopowder added to the base metal spreads in the microstructure without any particular problem. However, we see agglomeration of the nanopowder with increased rotational speed. The results obtained by optical microscopy were confirmed by electron microscopy and the relatively consistent presence of nanopowder in the microstructure of the parts was proved. Hardness tests showed that the addition of hybrid nanopowder mixture in the sample was made with a rotational speed of 1400 RPM resulted in about 15 % increase in hardness compared to the control sample. The wear test also showed that the specific wear rate decreased by ∼63 % with the addition of hybrid nanopowder in the same sample. The polarization test showed that the hybrid nanopowder can reduce the corrosion rate by approximately 132 % compared to the control sample. Also the corrosion rate of all the produced samples is lower than the consumable rod despite the extreme grain fineness.