Effect of the Microstructure on the Deformation and Fatigue Damage in a Gamma-TiAl Produced by Additive Manufacturing

In order to design efficient and light components for the gas turbine engine industry, new design criteria are needed for the application of gamma titanium aluminide alloys to safety critical components. In particular, novel manufacturing processes to produce gamma-TiAl alloys require investigating the influence of the microstructure in the local damage accumulation processes. In this work, the fatigue properties of a Ti-48Al-2Cr-2Nb alloy produced by additive manufacturing with Electron Beam Melting were examined by performing FCG and HCF tests at room and high temperature, in order to study the behavior of small cracks. By conducting additional monotonic and fatigue experiments, full-field residual strain maps were obtained by means of high- resolution Digital Image Correlation. High local residual inelastic strains were measured inside lamellar colonies, which are detected as the precursor to crack initiation, providing valuable information on the role of the intermetallic phases on the deformation and fatigue damage behavior of gamma-TiAl alloys.