Effects of nano-sized ceramic particles on the coefficients of thermal expansion of short SiC fiber-aluminum hybrid composites

Abstract

Coefficients of thermal expansion (CTE) for short SiC fiber-reinforced aluminum matrix hybrid composites (AMHCs) containing nano-sized SiC particles are predicted through a novel multi-step micromechanics approach. The thermo-mechanical properties of aluminum matrix filled with SiC nanoparticles are extracted utilizing an analytical micromechanics model as a first step. These effective properties are then used in the Mori-Tanaka method to obtain the effective CTEs of AMHCs. The modeling of nanoparticle agglomeration often formed in real engineering situations, is accomplished using a nested method. The predictions of the developed micromechanical model are compared to experimental measurements available in the literature, and an acceptable agreement is observed between them. The effects of the volume fraction, diameter and agglomerated degree of SiC nanoparticles, and also the volume fraction and aspect ratio of SiC short fibers on the AMHC CTEs are investigated. In addition to randomly oriented fiber-reinforced AMHCs, modeling of the effective CTEs of aligned short fiber-reinforced AMHCs is performed. The results reveal that addition of nano-sized SiC particles reduces the CTE of short SiC-fiber-reinforced AMHCs. The decrease of particle size and increase of fiber aspect ratio also assist in improving the overall thermo-elastic properties of AMHCs. However, the presence of the ceramic nanoparticle agglomeration leads to increase the AMHC CTEs. According to the micromechanical analysis, it is found that the alignment of short fibers is an efficient method to reduce the AMHC CTEs.