Abstract:In-situ observation was carried out on fatigue crack growth in centrifugal spray deposition (CSD) Ti-₄₈Al_-2Mn-₂Nb alloy with self-made SEM fatigue loading stage. The results show that the fatigue crack propagates with increase of cyclic stress level, while the cyclic number has a little effect on it. The lamellar structure has a great influence on fatigue crack propagation by torturing the crack growth path and changing the crack propagation direction. TEM observation shows that deformation twinning is sensitive to the cyclic stress level, and at the high cyclic stress level a large amount of deformation twins can be found, indicating that cyclic twinning becomes the dominant deformation mode at this stress level.

Key words: centrifugal spray deposition (CSD)　Ti-₄₈Al-₂Mn-₂Nb alloy　fatigue crack