Microstructure and thermal properties of binary ceramic particle-reinforced aluminum matrix composites with SiC/LAS

Multiphase particle-reinforced strategy shows promise for efficiently improving the comprehensive properties of aluminum matrix composites (AMCs) such as thermophysical and mechanical properties. In this work, AMC reinforced with β-eucryptite (LAS), and silicon carbide (SiC) particles were successfully prepared via a powder forging process. The microstructure morphology, interface compatibility, and coefficient of thermal expansion (CTE) of these composites were evaluated. Microstructural characterization illustrated that the co-effect of SiC and LAS resulted in a discontinuous phase with a microporous and deformation-free structure. The microporous structure of these composites was conducive for inward expansion and the elimination of internal stress, effectively limiting the outward thermal expansion behavior of the Al alloys. Moreover, SiC and LAS exhibited tight interfacial bonds with the Al grains, enhancing interfacial bonding strength. These composites provided practical and robust tensile stress that limited the thermal expansion of the Al matrix under heating. A fine Al grain size (53.5 nm) and low micro-strain (0.4 × 10–4) were obtained with increasing LAS content. Consequently, the composites achieved a low CTE of 17.27 × 10–6 K−1 at 500 °C. The experimental CTE values were also compared with theoretical values calculated by a rule of mixture model to confirm that the excellent interfacial bonding between the LAS and SiC reinforcements and the Al matrix imposed an effective constraint on matrix expansion.