Effect of microwave sintering on the microstructure and mechanical properties of Al-Al2O3-Si3N4 hybrid composite fabricated by powder metallurgy techniques

In the present investigation, Si 3 N 4 has been used in the partial replacement of SiC with Al/Al 2 O 3 composite for the application in the automobile industries parts. A microwave sintering technique was employed for the processing of the composite. The aluminum-based composite was developed with the constant 5 wt.% of Al 2 O 3 . The weight percent of Si 3 N 4 increased from 2.5% to 7.5%. Uniform distribution of the reinforcement particles was observed for the composition Al-5 wt.% Al 2 O 3 − 2.5 wt.% Si 3 N 4 composite and Al-5 wt.% Al 2 O 3 − 5 wt.% Si 3 N 4 composite. Optical microscope images Al-5 wt.% Al 2 O 3 − 5 wt.% Si 3 N 4 composite showed that the dispersion of the reinforcement (Al 2 O 3 and Si 3 N 4 ) has been done in a very fine and dense manner. Dispersion of reinforcement in a very dense manner helped in enhancing the mechanical properties of the composite. EDX pattern of Al-5 wt.% Al 2 O 3 − 5 wt.% Si 3 N 4 composite showed the maximum weight percentage of an element of Al, followed by Si, O, and N. Minimum porosity was found to be 0.045% for the composition Al-5 wt.% Al 2 O 3 − 2.5 wt.% Si 3 N 4 . However, the percent porosity of the Al-5 wt.% Al 2 O 3 − 5 wt.% Si 3 N 4 was 0.072%. The hardness, compressive strength, and tensile strength of aluminum were improved by about 82.85%, 18.94%, and 62.60% respectively with respect to aluminum after adding 5 wt.% Al 2 O 3 and 5 wt.% Si 3 N 4 . XRD of the Al/Al 2 O 3 /Si 3 N 4 composite showed the presence of Al, Al 2 O 3 , Si 3 N 4 , MgAl 2 O 4 , and Al 2 Cu phases. Thermal expansion and corrosion behavior were also observed to identify the Al 2 O 3 and Si 3 N 4 addition effect in the aluminum alloy.