5/26/2023 0 Comments Maximum action crack![]() ![]() These results indicated that the fatigue micro crack initiation was mainly caused by the stress concentration at room temperature, but at an elevated temperature (750 degrees C) the multi-cracks were caused by the coupled factors of both lamellar microstructure and stress concentration. The fatigue micro crack initiation and propagation tests of a TiAl alloy with 8% Nb content were carried out by using scanning electron microscopy in situ technology at room temperature and at 750 degrees C. In order to fill the gap between the understanding of the microstructure and fatigue cracking mechanism of TiAl alloys with high Nb content, and providing a criterion to evaluate next-generation crack formation models at different experimental conditions, this paper mainly investigates fatigue failure characteristics of TiAl alloys with high Nb content based on free surface crack detection by using in situ SEM technology and fracture surface analysis, including special attention paid to the influence of parameters such as lamellar microstructure and temperature effect. Therefore, to optimize the microstructure and improve HCF resistance of the TiAl alloy with high Nb content, an in situ SEM investigation should be conducted. These research results of LCF crack initiation and propagation behavior at RT cannot sufficiently reflect the governing mechanism in HCF situation of TiAl at different elevated temperatures, especially TiAl alloy with high Nb content.
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