Dry sliding wear characteristics of hybrid aluminum alloy with nano-fly ash and nano-yttrium oxide

Abstract

Aluminum alloys feature impressive levels of strength, ductility, castability, wear resistance, and corrosion resistance, making them highly advantageous for the aviation and automotive industries. This study investigates the dry wear performance of hybrid nanocomposites (HNCs) produced using Al6061 as the matrix, with nano-fly ash (FA) and nano-yttrium oxide (Y2O3) as reinforcing agents, utilizing the stir-casting method. The weight percentage (wt-%) of FA was fixed at 4 wt-%, while the Y2O3 varied from 1 wt-% to 3 wt-%. The specimens were prepared following ASTM-G99 standards and tested using a pin-on-disc apparatus with an E31 steel disc under four different loads: 10 N, 20 N, 30 N, and 40 N. It has been observed that wear rate has been increased with the increase in the applied load. The maximum wear rate has been recorded for the base Al6061 alloy as 5.63 × 10−4 mm3/N-m at 40 N load due to its lower wear resistance and less hardness value. The addition of reinforcement particles in the base alloy results in the grain refinement and improvement in the load-bearing capacity. It has been found that at 40 N load, the Al-6061 alloy reinforced with (4 wt-% FA + 3 wt-% Y2O3) is 56.83% superior in terms of wear resistance (2.43 × 10−4 mm3/N-m) as compared to Al6061 base alloy. The hybrid nano-composite containing 4 wt-% FA + 3 wt-% Y2O3 showed the highest value of microhardness as 123.2 HV, which is 136% higher than that of base alloy due to the higher load-bearing characteristics of the reinforcement particles. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) have been employed to analyze both unworn and worn surfaces, revealing uniform dispersion of reinforcement particles, the formation of an oxide layer, micro-pitting, wear debris, and material delamination. Grain refinement has been examined using the line intercept method (ASTM E1382-97), and X-ray diffraction (XRD) confirmed the elemental composition of the nano-reinforcements.