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

In the present investigation, zirconium dioxide (ZrO 2 ) and zirconium diboride (ZrB 2 ) 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 ZrO 2 . The weight percent of ZrB 2 increased from 2.5% to 7.5%. Uniform distribution of the reinforcement particles was observed for the composition Al–5 wt.% ZrO 2 –2.5 wt.% ZrB 2 composite and Al–5 wt.% ZrO 2 –5 wt.% ZrB 2 composite. The relative density of Al–5 wt.% ZrO 2 –5 wt.% ZrB 2 composite was found to be 0.9874. The percent porosity of the Al–5 wt.% ZrO 2 –5 wt.% ZrB 2 was 1.259%. Results showed that hardness, compressive strength, % tensile strength, and fatigue strength (at 1 × 10 7 cycles) were improved by about 74.28%, 18.18%, 58.77%, and 60.77%, respectively. XRD of the Al/ZrO 2 /ZrB 2 composite showed the presence of Al, ZrO 2 , ZrB 2 , MgAl 2 O 4 , and Al 2 Cu phases. The number of grains per square inch for composition Al–5 wt.% ZrO 2 –5 wt.% ZrB 2 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.% ZrO 2 –5 wt.% ZrB 2 composite. The fracture surface of the Al–5 wt.% ZrO 2 –5 wt.% ZrB 2 composite was composed of a dendrite structure with micro-porosities. Dimples were also not observed from the tensile fracture surface morphology of the composite.