Investigation of Mechanical and Tribological Behaviour of Heat-Treated Functionally Graded Al-7Si/B4C Composite

The current study focuses on improving the mechanical and reciprocating wear characteristics of centrifugally cast functionally graded A356(Al-7Si-0.3 Mg)/10 wt.% B4C composite through T6 heat-treatment. Comparative analysis was performed between as-cast and heat-treated composite. Metallographic analysis confirmed the presence of reinforcement particles alongside grain boundaries and spheroidised eutectic silicon particles in heat-treated composite. Outer layer of heat-treated composite displayed superior hardness (24.09%), ultimate tensile strength (44.8%) and tribological properties when compared to outer layer of as-cast composite. With increasing applied load (15, 25, 35 N), wear rate and co-efficient of friction increased whereas wear rate and co-efficient of friction decreased as sliding distance (500, 1000, 1500 m) increased. Worn morphologies confirmed extreme delamination wear and particle pull-out at high applied loads whereas traces of oxide formations were observed at high sliding distance. Heat-treated composites have superior characteristics due to the presence of spheroidised eutectic silicon particles and precipitate formation, which makes it an alternative material for reciprocating applications in aerospace and automotive industry.