Multifunctional A356 Aluminum Composites Reinforced with CeO2, MoS2, and Ni via Friction Stir Processing for Automotive and Electrical Applications

Abstract

This research paper incorporated and explored the different physical and chemical properties of three reinforcement materials-5 wt. % CeO2, 5 wt. % MoS2, and 3 wt. % Ni particles in aluminum composites processed by Friction Stir Processing (FSP) in multiple property domains for applications in automobile, electrical and electronic industries. The severe plastic deformation and dynamic recrystallization during FSP process led to significant grain refinement of the aluminum matrix and uniform-dispersion of the CeO2 and MoS2, which resulted in a refined grain structure and grain boundary strengthening. The dispersed ceramic particles and Ni particles act as nucleation sites for new grains during FSP process and pin grain boundaries, thereby restricting grain growth. This led to a finer, more homogeneous microstructure in the stir zone. Grains per square inch when examined through a 500 X magnification was determined to be 1520. The interfacial bonding layers between the matrix A356 and reinforcements CeO2, MoS2, and Ni fabricated using the FSP method revealed dendritic feature-like layers with robust and cohesive bond strength. Moreover, XRD revealed no formation of new intermetallic phases which confirmed an excellent processed composite. The refined grain structure (i.e. Hall-Petch effect) further contributes to the enhanced hardness (61.32 %), wear (56.8 %) and tensile strength (35 %) of the composite. The implantation of the particles contributed to lower wear rates and improved wear resistance. Corrosion resistance, performed in a 3.5 wt. % NaCl solution for 120 hours, revealed enhanced protection in aggressive environments pertaining to the development of protective oxide-layers by CeO2 and MoS2. Incorporation of 3 wt.% Ni substantially improved electrical performance and multi-pass FSP improved the metallic network, increasing conductivity by 10-15 % relative to the single-pass composite. Contact resistance on the other hand remained within the range required for low-current conduction, electronic housings, and heat-spreader applications, though still higher than base A356. These analyses underscored the multifaceted benefits of incorporating 5 wt. % CeO2, 5 wt. % MoS2, and 3 wt. % Ni particles in A356 composites fabricated through FSP method.