Study on the influence of manganese and silicon carbide in Al7075 metal matrix composite produced by P/M route

Abstract

The aluminium alloy-silicon carbide composite is widely used in the aircraft industry such as fuselage skins of aircraft, fuel entree covers and ventral fins in aircraft because of its low weight to high strength ratio, excellent corrosion protection at high temperatures and wear resistance and high hardness. In this work, powders of aluminium alloy 7075 (Al7075) is strengthened with silicon carbide (SiC) and manganese (Mn) in diverse fractions using a powder metallurgy approach to produce specimens of Al7075, Al7075 + 15 %Mn, Al7075 + 15 %Mn + 5 %SiC, Al7075 + 15 %Mn + 10 %SiC, Al7075 + 15 %Mn + 15 %SiC, and Al7075 + 15 %Mn + 20 %SiC. After fabricating, the specimens are subjected to microstructural analysis, X-ray diffraction (XRD), density, Rockwell hardness, and corrosion to find their suitability in engineering applications. The microstructure reveals the uniform dispersion of SiC and Mn in the Al7075 matrix. The hardness value decreases while increasing the SiC content above 15 % due to brittleness, but with the addition of Mn, the hardness value decreases as Mn induces ductility. It is inferred that the experimental density is lesser than the theoretical density due to the presence of small pores in the sample. Corrosion rate lowers with the inclusion of Mn to AL7075 and further decreases with higher fractions of SiC from 5 to 20 %.