Effect of zirconium diboride addition in zirconium dioxide reinforced aluminum-based composite fabricated by microwave sintering technique

Abstract

In the present investigation, zirconium dioxide (ZrO2) and zirconium diboride (ZrB2) have been used in the development of an aluminum-based composite. A microwave sintering technique was employed for the processing of the composite. The aluminum-based composite was developed with the constant 5 wt.% of ZrO2. The weight percent of ZrB2 increased from 2.5% to 7.5%. Uniform distribution of the reinforcement particles was observed for the composition Al–5 wt.% ZrO2–2.5 wt.% ZrB2 composite and Al–5 wt.% ZrO2–5 wt.% ZrB2 composite. The relative density of Al–5 wt.% ZrO2–5 wt.% ZrB2 composite was found to be 0.9874. The percent porosity of the Al–5 wt.% ZrO2–5 wt.% ZrB2 was 1.259%. Results showed that hardness, compressive strength, % tensile strength, and fatigue strength (at 1 × 107 cycles) were improved by about 74.28%, 18.18%, 58.77%, and 60.77%, respectively. XRD of the Al/ZrO2/ZrB2 composite showed the presence of Al, ZrO2, ZrB2, MgAl2O4, and Al2Cu phases. The number of grains per square inch for composition Al–5 wt.% ZrO2–5 wt.% ZrB2 composite was found to be 989.11. This result showed that a finer grain structure has been obtained after the solidification of Al–5 wt.% ZrO2–5 wt.% ZrB2 composite. The fracture surface of the Al–5 wt.% ZrO2–5 wt.% ZrB2 composite was composed of a dendrite structure with micro-porosities. Dimples were also not observed from the tensile fracture surface morphology of the composite.