Micromechanical study of elastic-plastic and thermoelastic behaviors of SiC nanoparticle-reinforced aluminum nanocomposites

Elastic-plastic and thermal expansion responses of aluminum (Al) matrix nanocomposites reinforced with silicon carbide (SiC) nanoparticles are investigated through a micromechanics analytical unit cell method. The formation of the interphase region between SiC nanoparticles and Al matrix is taken into account in the modeling of nanocomposites. The influences of some important parameters such as the thickness and material properties of the interphase, volume fraction and diameter of SiC nanoparticles on the elastic modulus, coefficient of thermal expansion (CTE) and elastoplastic stress-strain curve of the Al nanocomposites are studied in detail. The results clearly reveal high contribution of the interphase region to the overall mechanical and thermal behaviors of Al nanocomposites. It is found that when nanoparticle diameter is lower than about 150 nm, the decrease of SiC nanoparticle diameter leads to (i) an increment in mechanical properties both in the elastic and plastic regions and (ii) a reduction in CTE of the metal matrix nanocomposites. Also, the effect of interphase on the elastic modulus and CTE of Al nanocomposites becomes more important with the reduction of SiC nanoparticle diameter. Finally, the micromechanical model is employed to predict the elastoplastic behavior of SiC nanoparticle-reinforced Al nanocomposites subjected to multi-axial loading conditions in the presence and absence of the interphase region.