Microstructure and Dry Sliding Wear Behaviors of Microwave-Sintered Al-4.4Cu-0.7 Mg-0.6Si-B4C/nGr Hybrid Composites

Abstract

In recent years, more advanced mechanical and tribological properties have been needed in aluminum matrix composites due to the increasing variety of applications. For this purpose, second-generation aluminum matrix hybrid composites that have two or more different particle reinforcements are being developed today. In this study, in order to improve tribological and microstructural properties, nano-sized graphite and B4C-reinforced Al-4.4Cu-0.7 Mg-0.6Si aluminum alloy hybrid composites were produced. As a sintering method, the microwave sintering technique, which is one of the fast sintering methods, was preferred to prevent and/or minimize the formation of unwanted reaction products. In Al-4.4Cu-0.7 Mg-0.6Si-B4C/nGr hybrid composites, 4 different (3, 6, 9 and 12 wt %) B4C and 1 wt % nGr reinforcements were used. Raw samples, compressed by the one-way cold pressing method under 600 MPa pressure, were sintered in the microwave oven at 550 °C temperature for 60 min. In XRD analyses, whereas any unwanted reaction product (Al4C3, Al3BC, etc.) was not detected, θ-Al2Cu precipitate formations were detected. In hybrid composites where no graphite agglomeration was observed within the matrix, the highest hardness value (103.9 Hv0.05) was determined in the sample containing 6 wt % B4C and the lowest specific wear rate (0.271 × 10–3 mm3/Nm) was determined in the sample containing 12 wt % B4C.