Effect of interfacial reaction on the thermal expansion behavior of β-eucryptite particle and aluminum borate whisker reinforced 6061 aluminum alloy composite

A new aluminum matrix composite containing β-eucryptite particles and aluminum borate whiskers was obtained by a squeeze casting technique. This composite exhibits a low coefficient of thermal expansion (CTE) and high strength. The interfacial reactions on both the surface of β-eucryptite particle and the surface of aluminum borate whisker in the composite were studied by transmission electron microscopy and X-ray diffraction. The effect of interfacial reaction on the CTE of the composite was investigated in detail. The results indicate that the interfacial reaction product on the surface of β-eucryptite particle is Mg2SiO4 (forsterite). The solution treatment at 520 °C has little effect on the interfacial reaction on the aluminum borate whisker, but the degree of interfacial reaction on the surface of β-eucryptite particle increases with solution treatment time. The coefficient of thermal expansion of the composite is affected greatly by the degree of interfacial reaction on the surface of β-eucryptite particle.