Influence of T6 heat treatment on the microstructure and tribological properties of ADC12-GNPs composites

The graphene nanoplatelets (GNPs) were used as reinforcement to fabricate the ADC12-GNPs composites via ultrasonic-assisted casting, then the composites were adopted T6 heat treatment. The microstructures and wear performance were investigated in detail. The GNPs effectively refined the alpha-Al grains and form a strong Al-GNPs interfacial structure with the matrix, and the T6 heat treatment further rounded the Si phases and precipitated nanoscale theta '-Al2Cu. With the increase of load, the wear rate increases. And with the increase of sliding velocity, the wear rate shows a tendency of decreasing and then increasing. The wear rate and COF of the ADC12-GNPs/T6 composites showed a maximum reduction of 63.3 % and 39.2 %, respectively, compared to the matrix. The selflubrication and refinement strengthening effect of GNPs improved the wear resistance, and the interaction between nanoscale theta '-Al2Cu precipitates and dislocations enhanced the tribological properties. Wear morphology and three dimensional profile analysis showed that the surface roughness of the ADC12-GNPs/T6 composite was 2.73 mu m, which was 150 % lower than that of the matrix (6.82 mu m) when the sliding velocity was 0.28 m/s and the load was 40 N, showing typical abrasive wear characteristics.