Microstructure and Corrosion Characteristics of Dual Reinforced (SiC-B4C) Al Matrix Composites Produced by Powder Metallurgy Process

In the current investigation, powder metallurgy was used for effective production of a hybrid aluminum matrix that was reinforced with SiC and B4C particles. The effects of reinforcements (SiC and B4C) on the microstructure of the composites, wettability and tribological behavior were examined. Aluminum (Al) matrix with reinforcements of silicon carbide (SiC) at weight percentages of 2, 3, 4, 5 and 6 was produced through powder metallurgy (PM) method, and also hybrid Al composites reinforced by SiC at different weight percentages of 2, 3, 4, 5 and 6 with constant addition of boron carbide (B4C) with 2 wt.%. The microstructure analysis was carried out with a scanning electron microscope (SEM) indicated the uniform distribution of reinforcement particles throughout the aluminum matrix. The microstructures of aluminum showed an increase in porosity, with increase in SiC and B4C concentration. Studies carried out using electron backscatter diffraction (EBSD) indicated the inclusion of SiC particles into Al composites bringing about a finer grain structure of the composite. The higher hardness value was obtained for Al + SiC(6 wt.%) and Al + SiC(4 wt.%) + B4C(2 wt.%) composites as 50 and 54 HV, respectively. The composite's hardness was enhanced as a result of grain refinement and increased resistance to dislocation motion. The higher compression strength was obtained for Al + SiC(4 wt.%) and Al + SiC(4 wt.%) + B4C(2 wt.%) composites as 247 and 300 MPa, respectively. The Al + SiC(2 wt.%) and Al + SiC(6 wt.%) + B4C(2 wt.%) composite samples' thermal conductivity was 86.04 and 68.07 W/mK, respectively. The higher corrosion resistance of Al + SiC(2 wt.%) + B4C(2 wt.%) hybrid composite sample was determined to be 0.706 mpy.