Damage Evolution and Mechanical Properties After Impact of the TiAl Alloy TNBV3B

Kurzfassung

TiAl alloys show a low ductility, which limits their application especially in components prone to impact damage like turbine blades or vanes. Therefore, the influence of high-speed impact damage on the mechanical behaviour of a cast and a forged version of the intermetallic TiAl alloy TNBV3B has been investigated. Ballistic tests were performed with impact energies up to several Joules. In order to approach the impact situation with real blades or vanes, a blade-like geometry was chosen for the specimen edges. The caused damage has been evaluated as a function of the impact speed, the particle weight and the location of the impact. The location of the impact on the specimen plays an important role as the damage increases with increasing distance until a critical value is reached depending on the local thickness and the energy. Fatigue experiments (R=0.1) at different temperatures were performed to determine the threshold for crack growth as a function of the damage size of the material after impact. For these tests, specimens showing cracks with up to 2 mm length on the specimen back side and specimens showing blow-outs were chosen.