Interfacial reaction and its influence on the mechanical properties of the ASZ short fibre-reinforced Al alloy composite

The effect of interfacial reaction on the mechanical properties of the AC8A A1 alloy reinforced with ASZ short fibres (ASZ/AC8A composite) was studied. In the ASZ/AC8A composite, the interfacial reaction was observed to proceed between the SiO₂ binder layer and Mg of the matrix to form MgA1₂O₄ at the interface. Formation of MgA1₂O₄ was believed to enhance the interfacial bonding strength, resulting in the improved composite strength. However, the interfacial reaction in the ASZ/AC8A composite always took place at the expense of Mg in the matrix, resulting in the composite devoid of the Mg bearing precipitates such as A1₂CuMg and Mg₂Si. Interfacial reaction mechanisms were investigated for composites containing various Mg contents. The resultant mechanical properties of the composite were measured to determine the adequate amount of Mg within the composite. Microstructural changes of the composite were observed using transmission electron microscopy and differential scanning calorimetry to provide qualitative analyses on the experimental observations.