Preparation and Reactive Sintering of Nano- Crystalline TiO2-Al Powder

Intermetallic alloys based on γ-TiAl have relatively low density, high strength to weight ratio, good oxidation and corrosion resistance and adequate creep resistance at high temperatures. However, they suffer from brittleness and rapid crack growth rate at low to intermediate temperatures [1]. Development of in-situ TiAl / Al2O3 composite may help to overcome the problems associated with the monolithic γ-TiAl alloys. Such a composite material can be produced by mechanical activation and subsequent heat treatment of TiO2 and Al powders. Presence of fine and homogenously distributed ceramic particles in the intermetallic matrix may improve the ductility, at least if this property is controlled by planar slip. In addition the final phases in such a composite are thermodynamically compatible [2].In this research an ultra-fine grained composite structure consisting of an intermetallic matrix together with dispersed nano size Al2O3 obtained via mechanical activation of TiO2 and Al.The effect of milling parameters and phase evolutions after sintering at different temperatures was observed on this system.