Metallographic, mechanical and reciprocating wear characterization and behavioural studies of untreated and T6 treated Al2O3/Al7Si0.3Mg functional composite material

Abstract

The microstructural, mechanical and unlubricated reciprocating wear characteristics of functionally graded 10 wt% Al2O3/Al7Si0.3Mg composite were analysed under untreated (UT) and heat-treated (HT) conditions. Microstructural analysis revealed Al2O3 particle gradation across the thickness and particle clusters in UT composite, whereas fine α-Si spheroids were observed in HT composite. Transmission electron microscopy studies on the HT composite revealed iron intermetallic and nano-sized β-Mg2Si precipitate phases, whilst electron backscatter diffraction studies show morphological changes in the α-Al grain structure after heat treatment. UT and HT composites underwent reciprocating wear trials under varying wear parameters (applied load and sliding distance) using a pin-on-flat plate linear reciprocating tribometer. Worn morphologies for both UT and HT composites were studied using a scanning electron microscope to investigate the wear mechanisms involved and atomic force microscopy to understand the difference in surface roughness. Response Surface Methodology is used to conduct statistical analysis and response optimisation on UT and HT composites. Due to Al2O3 particles and silicon spheroids, the HT composite outperformed the UT composite. According to the investigation, the wear resistance of both composites had increased (20–40%) with increasing reinforcement content but decreased with increasing wear parameters.