X-ray fractographic study on TiAl alloys with various types of microstructures

The fracture toughness test was conducted on γ + α2 two-phase TiAl alloys with lamellar, duplex and near-γ structures. The x-ray fractographic technique was applied to the fracture surfaces. The plastic zone size wy was determined on the basis of the distributions of the residual stress and the half-value breadth beneath the fracture surfaces. Although the fracture mode shows microstructure dependence, ωgamma is related to the fracture toughness value KIC and the yield stress σγ as: ωy=α(KIC/σY)2 where α is 0.13