Reaction Synthesis of TiAl-Al2O3 Composites from Ti-Al-Cr2O3

Titanium aluminide composite reinforced with in situ formed submicron Al(2)O(3) has been prepared by a reactive hot press method using Cr(2)O(3), Al and Ti powder as starting materials. The reaction synthesis processing is particularly investigated. Results show that the matrix of the as-prepared material is a mixture of TiAl and a small amount of Ti(3)Al and Cr containing phase. Fine Al(2)O(3) particles that act as reinforcing phase are dispersed along the interface of the matrix. The formation of TiAl/Al(2)O(3) composite involves many transitional stages. Firstly, TiAl(3) and Ti(3)Al intermediates were produced, then reducing reaction of Cr(2)O(3) by Al formed Al(2)O(3), and finally, the competitive solid-state diffusing reactions among Ti(3)Al, TiAl and TiAl(3) produced the matrix phases of the TiAl/Al(2)O(3) composite.