Characterization and Tribological Properties of Novel AlCu4.5SiMg Alloy–(B4C/TiO2/nGr) Quaternary Hybrid Composites Sintered via Microwave

Abstract

In the future, hybrid aluminum matrix composites, which are the second generation composites, will be replaced by solid reinforced third-generation quaternary hybrid composites in which nano- and micro-scale reinforcement particles are used together. In this study, microwave sinterability of B4C, TiO2 (nm + µm), and nGr reinforced quaternary hybrid composites that had AlCu4.5SiMg alloyed Matrix, and their microstructural and tribological properties after sintering were examined. The proportion of nGr in the composite sample was taken as 0.5 wt%, while B4C and TiO2 were used in three different proportions (3, 9, 12 wt%). After being compressed under 600 MPa pressure, the composite samples were sintered for 60 min at 550 °C by a microwave oven with a power of 2.9 kW and a frequency of 2.45 GHz. It was determined that due to its high microwave absorbency, B4C reinforcement improved the microwave sinterability more compared to TiO2. In XRD analyses, whereas Al4C3 and Al3BC reaction products were not seen as harmful, the intermetallic phase of Al2Cu was detected. It was determined that both friction coefficient and wear resistance increased as the proportion of B4C increased in composite samples. In AlCu4.5SiMg–(12 wt% B4C/3 wt% TiO2/0.5 wt% nGr) quaternary hybrid composites with the highest hardness (97.6 HV), the lowest specific wear rate (0.118 mm3 Nm × 10−3) was detected.