Estimation of yield strength and elastic modulus of aerospace-grade aluminum 7075 composite reinforced with silicon carbide and graphite

This study aims to find a suitable theoretical model to estimate yield strength and elastic modulus of the AA7075 base cast and hybrid composite reinforced with silicon carbide and graphite (micron-sized) to attain high quality, high performance, and low-cost metal matrix composite. Compared to AA7075 base cast CM1 (AA7075 base cast) ultimate tensile strength, yield strength, and flexural strength of hybrid composite CM4 (AA7075 + 15 wt% SiC + 5 wt% Graphite), CM3 (AA7075 + 10 wt% SiC + 5 wt% Graphite), and CM2 (AA7075 + 5 wt% SiC + 5 wt% Graphite) increased (29%, 24%, and 19%), (36%, 35%, and 27%), and (19%, 13%, and 6%) respectively. Micro-mechanics contributed higher, followed by other strengthening mechanisms like load transfer, grain refinement, and thermal mismatch with respect to the volume fraction of the reinforcement particle in the aluminum metal matrix. In the yield strength model, Ramakrishnan-Modified Shear Lag-Mirza and Chen model, Li model, sum of contribution model, and proposed model estimated closer values. They agreed with experimental data at all values up to 7.34% of reinforcement volume fraction. In the elastic modulus model, Hashin-Shtrikman - average, upper, and lower bound and the proposed model estimated well and agreed with experimental data at lower and higher volume fractions of reinforcement.