Microstructures and mechanical properties of (Ti,Cr)Al/Al2O3 composites fabricated by reactive hot pressing from Ti, Al and Cr2O3

Titanium aluminide composites reinforced with in situ formed Al2O3 were fabricated by a reactive hot press method, using Cr2O3, Al and Ti powders as raw materials. The effect of Cr2O3 addition on the microstructures and mechanical properties of the (Ti,Cr)Al/Al2O3 composite was characterized. The results show that the TiAl matrix is refined gradually with increasing the amount of Cr2O3. The Vickers-hardness and densities of the (Ti,Cr)Al/Al2O3 composite increase gradually with increasing Cr2O3 content. When the Cr2O3 content is 4.47 wt.%, the compressive strength, flexural strength and fracture toughness of the composite reach the maximum values of 1032 MPa, 634 MPa and 9.78 MPa m(1/2), which are substantially higher than those of the monolithic TiAl based alloy by about 18%, 78% and 80.5%, respectively. The increase in mechanical properties for the (Ti,Cr)Al/Al2O3 composite is due to the toughening effect arising from the combination of Cr solid solution in TiAl matrix and in situ formed Al2O3. (c) 2013 Elsevier B.V. All rights reserved.