In situ fabrication of Al_3Ti particle reinforced aluminium alloy metal-matrix composites

摘要

Titanium tri-aluminide (Al_3Ti) particles were dispersed homogeneously into a castable aluminium alloy matrix by the aluminothermic reduction of hexafluorotitanate (K_2TiF_6) under different conditions. Al_3Ti particles in different morphologies and sizes were produced by changing the fabrication conditions, such as composition of the flux, the temperature and holding time. The coarsening and growth of the Al_3Ti particulates are principally affected by other elements present in the flux during fabrication. The effects of the temperature and holding time, alloying elements and the composition of flux on the dispersion of the reinforcement were examined by using SEM and X-ray diffraction techniques. The observed results are explained in terms of the different growth behaviour of the Al_3Ti particles under different conditions. The dispersion of the Al_3Ti particles and the Al/Al_3Ti interfacial bonding are explained by the solidification of aluminium.