High temperature fatigue properties of Ti-22Al-25Nb alloy double slats
The axial high-cycle fatigue behavior of Ti-22Al-25Nb alloy multi-scale double slats at 300,500 and 700℃ was studied,and the fracture and structure morphology of fatigue samples were characterized.The results showed that the fatigue limits were 510,338 and 356 MPa,respectively.The cracks of 300 ℃ samples have both surface and internal nucleation,and the cracks of 500 and 700 ℃ samples originated from the surface of the sam-ples.The fatigue striations at 300 ℃ show the characteristics of brittle bands,the intermittent and continuous tran-sition striations at 500 ℃,and the plastic striations at 700 ℃.Small acicular O-phase slats are prone to crack,while large sheet slats hinder the crack propagation path,which is conducive to improving the fatigue life of the ma-terial.
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