Thermal expansion anisotropy in extruded SiC particle reinforced 2080 aluminum alloy matrix composites

Thermal expansion behavior is an important physical property of metal matrix composites (MMCs). For extruded Al/SiC_p composites, both the particle volume percent and the orientation relative to the extrusion direction have significant effects on the coefficient of thermal expansion (CTE) of a composite. In this study, the coefficient of thermal expansion of extruded, SiC particle reinforced 2080 Al composites were measured using a thermal mechanical analyzer (TMA). It was found that the anisotropic distribution of SiC particles determines the anisotropic thermal behavior of Al/SiC_p composites. For the same SiC content, the CTE in the short transverse direction (normal to the extrusion axis) is higher than that in the transverse direction, with the longitudinal direction (parallel to the extrusion axis) having the lowest CTE. Finite element modeling (FEM), based on the actual microstructure of Al/SiC_p composites, was employed to simulate the thermal behavior. The experimental results for the CTE of the composite correlated very well with those predicted by two-dimensional (2D) numerical models. The FEM results showed that orientation of SiC particles changes the internal stress in the composite, which yields anisotropic thermal behavior. A comparison was made between the experimental results and the FEM model, and these were related to several analytical models.