Development of TiB 2 -GNP reinforced Al6061 nano-hybrid composites with enhanced wear and mechanical properties

Abstract

In this study, nano-hybrid composite materials were produced via powder metallurgy (PM) by adding TiB₂ and graphene nanoplatelets (GNPs) to Al6061 alloy, known for its high ductility, corrosion resistance, and weldability. Sub-150 µm Al6061 powder was used as the matrix, while reinforcement elements included sub-5 µm TiB₂ and 5 nm thick, 18 µm diameter GNPs. Six different materials were fabricated: pure Al6061, Al6061 + 10% TiB₂, and Al6061 + 10% TiB₂ with 0.25%, 0.5%, 1%, and 2% GNP additions. The powder mixtures were first dispersed in ethanol and ultrasonically agitated at 53 kHz for 60 min, followed by magnetic stirring at 580 rpm. Ethanol was removed via vacuum drying, and the dried powders were mixed in a 3D mixer for 30 min with a 1:5 powder-to-ball ratio. Cold pressing was performed at 50 MPa, followed by sintering at 550°C for 30 min and hot pressing at 200 MPa. After cooling to room temperature, T6 heat treatment was applied. Microstructure, density, hardness, tensile strength, and wear properties were examined. Increasing the reinforcement ratio reduced density. While hardness decreased with higher GNP content, tensile strength improved. Wear tests showed that TiB₂ and GNP additions significantly reduced volume loss. The lowest wear was observed in the 10% TiB₂ + 1% GNP sample. Due to the self-lubricating effect of GNPs, the coefficient of friction also decreased, with the lowest value recorded for the 1% GNP-reinforced composite.