Mechanical Properties of a Low-thermal-expansion Aluminum/Silicon Composite Produced by Powder Metallurgy

Al matrix composite containing high volume fraction silicon has been promising candidate for lightweight and low-thermal-expansion components. Whereas, optimization of its mechanical properties still is an open challenge. In this article, a flexile powder metallurgy processing was used to produce a fully dense Al–4.0Cu (wt%) alloy composite reinforced with 65 vol.% Si particles. In this composite, Si particles were homogenously distributed, and the particle size was refined to the range of 3–15 μm. Tensile and flexural strength of the composite were 282 and 455 MPa, respectively, about 100% and 50% higher than the best properties reported in literature. The measured fracture toughness of the composite was 4.90 MPa m1/2. The improved strength of 65%Si/Al was attributed to the optimized particle characteristics and matrix properties. This investigation is expected to provide a primary understanding of the mechanical behaviors of Si/Al composites, and also promote the structural applications of this low-thermal-expansion material.