Undercooling of superalloys and casting quality of single-crystal turbine blades

以往的高温合金研究主要集中在高温性能的改善上，而没有考虑单晶成分的可铸性。在这项提交的研究拨款中，将对当今高温合金的过冷度进行系统的研究，以调查它们对铸造缺陷的敏感性。本项目的重点是最新的第四代高温合金。我们将对这些问题进行研究，以找出有助于实现足够过冷度的机制，从而使制造单晶组件和复杂几何形状(如涡轮叶片)成为可能。在这里，基本的科学问题，如复杂多元合金在有问题的条件下的形核和枝晶生长，将处于我们研究的前沿。过冷度对成分的依赖关系应通过统计回归、系统合金化添加和相应的组织特征来确定。应深入研究关键合金化元素的影响。这项研究的结果将对高温合金的发展做出重要贡献，并将有助于实现所需机械性能与制造单晶部件所需浇注性能的最佳组合。

Previous superalloy development focussed on the improvement of high temperature properties without considering the castability of single-crystal components. In this submitted research grant the undercoolability of today's superalloys will be systematically researched in order to investigate their susceptibility to casting defects. The focus of this project is on the latest 4th generation superalloys. These will be examined in order to find out about mechanisms contributing to the achievement of a sufficient undercooling to make the manufacturing of single-crystal components and complex geometries like turbine blades possible.Here, fundamental scientific questions such as the nucleation and dendrite growth of complex multicomponent alloys under problematic conditions will be at the forefront of our research. The dependency of the undercooling on the composition shall be determined by statistic regression, systematic alloying addition and correspondent microstructure characterisation. The impact of critical alloying elements shall be investigated in depth.The results of this study will form an important contribution to the development of superalloys and will help to achieve an optimal combination of the desired mechanical properties with the required castability for the manufacturing of single-crystal components.