Dwell fatigue crack growth in next generation RR1073 nickel disc alloys

在该项目中，将研究影响保压疲劳裂纹扩展行为的微观结构因素。它将采用先进的材料表征技术，如分析透射电子显微镜（TEM），以了解底层微观结构的影响。在航空航天工业中，对能够承受燃气涡轮机内越来越高的温度的镍基高温合金有很大的需求。允许涡轮机在更高的温度下操作在其热力学效率和燃料消耗方面是有益的。然而，这些材料必须能够承受蠕变变形，氧化和其他超出当前限制的环境过程。RR 1073需要严格的机械测试，以确定其在温度下的可行性。一个中心的研究兴趣在于观察这种新的镍基高温合金的驻留疲劳裂纹扩展，它将用于航空发动机燃气涡轮机的转子盘应用。由于在飞行器飞行期间，特别是在起飞期间经历的循环载荷，在高温合金中发生驻留疲劳。因此，重要的是要了解如何通过控制微观结构，最重要的是通过控制γ ′沉淀物的分布来优化保压裂纹扩展阻力。该方案将包括详细调查老化温度和冷却速率对这种分布发展的影响。

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.