Integrated experimental and numerical study of wear behaviour in ultrasonically stir-cast Al7075 nano-hybrid metal matrix composites

Finite element wear modelling is useful only if a wear coefficient obtained for one material can predict another. Five Al7075 castings, an unreinforced alloy and four composites reinforced with 30 to 40 nm SiC, B 4 C and Al 2 O 3 in binary and ternary combinations were produced by ultrasonic-assisted stir casting and tested by pin-on-disc dry sliding against hardened EN31 steel at 15 to 60 N over 2700 m. The ternary composite reached 157.86 ± 3.48 HV, 14.3% above the unreinforced alloy, with the lowest wear depth at every load. A three-dimensional Archard model was built in ANSYS Mechanical. The pressure exponent was obtained from the measured load dependence as 1.345, and the wear coefficient calibrated on the unreinforced alloy and three binary composites only. It fell by 47% across that set, while hardness increased by 9%, showing that the reinforcement acts by a mechanism hardness alone does not describe. The coefficient for the ternary composite was predicted rather than fitted; its simulations agreed with experiment to a mean absolute error of 5.76%, against 5.68% for the calibrated compositions. Regression of predicted against measured wear depth gave a slope of 0.946 and R 2 of 0.990.