Positron Lifetime and EBSD Studies of Mechanically Fatigued Titanium Alloy

Positron annihilation lifetime measurement and Electron Backscatter Diffraction (EBSD) were evaluated the fatigue damage by detecting defects such as dislocations or strain in Ti-6Al-4V. Samples of various degrees of low-cycle fatigue with strain control in room temperature were carried out. This alloy changed the microstructure by heat treatment of furnace cooling, air cooling and water quench. In the case of air cooling or water quench sample, the lamellar structure was observed. Positron lifetime was changed by the rate of cooling. In the case of fatigued sample, KAM map was not changed before and after fatigue. However, the positron annihilation lifetime measurement exhibited a proportional increase in the positron lifetime with the fatigue damage to cycle to failure, showing that the relationship between fatigue damage and positron lifetime.