The Microstructures and Mechanical Properties of V2O5-Doped Al2O3/TiAl In-Situ Composites by Reactive Hot Pressing Process.

Al ₂O ₃/TiAl composites are successfully fabricated by the in-situ hot pressing method from the elemental powders of Ti, Al, TiO ₂, and V ₂O ₅. The effect of V ₂O ₅ addition on the microstructure and mechanical properties of the Al ₂O ₃/TiAl in-situ composites is investigated in detail. It is found that the as-synthesized composites mainly consist of V-dissolved γ-TiAl, α ₂-Ti ₃Al, and Al ₂O ₃ particles along with a small amount of V ₃Al phase, and the in-situ-formed fine Al ₂O ₃ particles tend to disperse on the grain boundaries of TiAl matrix. With increasing V ₂O ₅ content, the density and Vickers hardness of the resulting composites gradually increase, whereas the fracture toughness and flexural strength first increase and then decrease with the increase of V ₂O ₅ content. The composite with 3.5 wt.% V ₂O ₅ has the maximum value of 9.35 MPa m ^1/2 and 713.36 MPa for the fracture toughness and flexural strength, respectively. The toughening mechanism is also discussed in detail. [ABSTRACT FROM AUTHOR]