Interface investigations of alumina and aluminosilicate short-fiber-reinforced aluminum-alloy composites

The interfacial microstructures of alumina (Al2O3) and aluminosilicate (Al2O3·SiO2) short-fiber-reinforced aluminum-alloy composites were studied by means of transmission electron microscopy (TEM). The experimental results showed that the SiO2 content in the fiber has a marked effect on the interface microstructures of the composites even though a silica binder is not used. The reaction product MgAl2O4 spinel oxide was formed at the interface of the aluminosilicate-fiber-reinforce aluminum-alloy composite, however, no spinel oxide was observed at the interface of alumina-fiber-reinforced composite. The alumina fiber could act as a heterogeneous nucleation substrate for the primary silicon phase as a result of the low disregistry (5.62%) between the (0001) of δ-Al2O3 and the (110) of silicon.