Al 2 O 3 particle-reinforced TiAl composites are successfully reaction-synthesized from the powder mixture of Ti, Al, TiO 2 , and Nb 2 O 5 , using the hot pressing reaction synthesis technique. The microstructure and mechanical properties of the as-sintered products are investigated. It is found that in the as-sintered products consisting of -TiAl, 2 -Ti 3 Al, Al 2 O 3 , and NbAl 3 phases, the fine Al 2 O 3 particles tend to disperse on the grain boundaries. With the Nb 2 O 5 content

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... the grains are remarkably refined and the Al 2 O 3 particles are dispersing more uniformly in the TiAl matrix, forming a partial lamellar structure containing and lamellar phases. The hardness of the in-situ composites increases gradually, and the bending strength and the fracture toughness of the as-sintered products reach the maximum value of 398.5 MPa and 6.99 MPa·m 1/2 , respectively, as the Nb 2 O 5 content increases to 6 wt%.