Microstructure and Mechanical Properties of TiAl-based Alloy

Two phases gamma titanium aluminide alloy,Ti-46.5Al-2.5V-1Cr.was investigated to characterize microstructures and to define the microstructure/mechanical property relationship.Many kinds of microstructure of gamma and α_2 phases were obtained by heat treatments in the α+γ,α_2+γ and α fields.The effects of microstructure on tensile properties,fracture toughness and J-R resistance curve at room temperature,were systematically studied.The experimental results showed that the microstructure had a strong effect on mechanical properties,The duplex microstructure produced by heat treatment at 1250℃×4 h with controlled cooling resulted in the highest ductility of 4.8% tensile elongation,low fracture toughness and crack growth resistance.The fully lamellar microstructure produced by heat treatment in the α field having large grain sizes resulted in the highest fracture toughness but the lowest ductility.