Dwell fatigue crack growth in next generation RR1073 nickel disc alloys

在该项目中，将研究影响暂态疲劳裂纹扩展行为的微观结构因素。它将使用先进的材料表征技术，如分析-透射电子显微镜(TEM)，以了解潜在微结构的影响。在航空航天工业中，对镍基高温合金的需求很大，这种合金可以承受燃气轮机中越来越高的温度。允许涡轮机在更高的温度下运行在热力效率和燃料消耗方面是有益的。然而，这些材料的制造必须能够承受蠕变变形、氧化和其他超过当前限制的环境过程。RR1073需要严格的机械测试来确定其在温度下的生存能力。一个主要的研究兴趣是观察这种新型镍基高温合金的驻留疲劳裂纹扩展，这种合金将用于航空发动机燃气轮机的转子盘。高温合金由于在飞机飞行过程中，尤其是在起飞过程中所经历的循环载荷，会产生驻留疲劳。因此，重要的是要了解如何通过控制微观组织，最重要的是通过控制伽马素析出物的分布来优化驻留裂纹扩展阻力。该方案将详细调查老化温度和降温速度对这种分布的发展的影响。

Within this project microstructural factors which affect the behaviour of dwell fatigue crack growth will be investigated. It will employ advanced material characterisation techniques such as analytical-Transmission Electron Microscopy (TEM) to understand effects of underlying microstructure. In the aerospace industry there is great demand for nickel-based superalloys which can withstand the increasingly higher temperatures found within gas turbines. Allowing turbines to operate at higher temperatures is beneficial in terms of their thermodynamic efficiency and fuel consumption. However, these materials must be manufactured to be able to withstand creep deformation, oxidation and other environmental processes beyond current limitations.RR1073, requires rigorous mechanical testing to determine its viability at temperature. One central research interest lies in observing dwell fatigue crack growth for this new nickel-based superalloy, which will be used for rotor disc applications in an aero-engine gas turbine. Dwell fatigue occurs in the superalloys due to the cyclic loading experienced during aspects of an aircraft's flight and especially during take-off. Therefore, it is important to understand how to optimise dwell crack growth resistance through controlling microstructures and most importantly by controlling the distributions of gamma prime precipitates. The programme will involve detailed investigation of the effects of ageing temperatures and cooling rates on the development of such distributions.