Fatigue cracking in gamma titanium aluminide
英文摘要：
Cast and HIP'ed \textgamma-TiAl 4522XD is being developed for use in jet engine low pressure turbine blades, where temperature variations occur through the flight cycle. The effects of temperature variations on fatigue cracking were therefore examined in this study. It was found that fatigue crack growth rates were higher at 750C than 400C, but that $ΔK_\mathrm{th}$ was also higher. Temperature excursions between 400 and 750C during fatigue crack growth resulted in retardation of the crack growth rate, both on heating and cooling. It was also found that for notches $0.6$~mm in length and smaller, initiation from the microstructure could instead be observed at stresses similar to the material failure stress; a microstructural initiation site exists. A change from trans- to mixed trans-, inter- and intra-lamellar cracking could be observed where the estimated size of the crack tip plastic zone exceeded the colony size.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
