Al/SiC nanocomposites with enhanced thermomechanical properties obtained from microwave plasma-treated nanopowders

Abstract

Al-based composites with enhanced thermomechanical properties are in high demand. However, obtaining a uniform distribution of the strengthening phase in the metal matrix and achieving a strong metal/ceramic interface is still a great challenge. In this work, nanoAl/nanoSiC powder mixtures after high-energy ball milling were treated with Ar microwave plasma. Plasma processing was designed to remove the initial oxide film covering Al nanoparticles (NPs) and adsorbed impurities from the surface of SiC NPs, improve the wetting of SiC with Al melt, prevent SiC nanoparticle agglomeration, and ensure their uniform distribution in the metal matrix. During plasma treatment, Al/SiC composite particles were obtained, which were subsequently utilized as ready-made structural blocks with uniformly distributed reinforcing SiC NPs to obtain Al/SiC composites with 5, 10, and 30 wt% of SiC. Spark plasma sintered Al/SiC composites using plasma-treated powder mixtures showed approximately 20% higher tensile strength. The addition of 10% SiC led to an increase in hardness by 480% (145 HV), tensile strength by 70% (317 MPa) and 95% (238 MPa) at 25 °C and 500 °C, respectively, compressive strength by 135% (578 MPa), and wear resistance by 35–50%. The effect of point defects at the Al/SiC interface, such as impurity oxygen atoms and Si monovacancies, on the binding energy and temperature-dependent critical shear stress at the interface was assessed using molecular dynamics simulations with machine learning interatomic potentials. Our study demonstrated that the plasma-chemical treatment of Al/SiC powder mixtures is a promising approach for improving the thermomechanical properties of the Al/SiC composites.