A fundamental study of deformation mechanisms in advanced polycrystalline nickel-base superalloys

作为最重要的高温结构材料之一，镍基高温合金具有独特的高温性能，这使其成为要求苛刻的应用的首选，例如飞机和发电应用的涡轮发动机的热部件。镍基高温合金依靠基体强化和沉淀硬化的结合来获得优异的高温机械性能。本研究项目将研究高级γ（基体）/ γ素数（析出相）镍基高温合金中γ素数析出相分布对变形机制的影响。它采用跨学科的方法，结合详细的冶金研究，中子和高能x射线同步加速器衍射光束线的原位力学测试和数学建模。而不是研究宏观力学性能作为微观结构的函数，我们的方法将允许我们直接研究强化机制作为微观结构的函数。在先进的高温合金中，基础研究常常受到微观结构复杂性的限制。我们将克服这一点，首先研究简化的模型微观结构，并使用这些来验证和调整先进的模型，然后再转向商业上更相关但也更复杂的微观结构。该项目将提供对γ质点分布和变形机制相互作用的改进的基本理解，这是利用这些新型高温合金的全部潜力的关键。尽管最近世界范围内出现了许多新的伽玛prim强化多晶镍基合金，但迄今为止，通过热机械加工来优化这些合金的机械性能仍然是经验主义的。这一新的认识将使确定最佳显微组织成为可能，这不仅有助于确定新开发合金的理想热机械加工路线，而且为今后的合金开发指明方向。

As one of the most important classes of high-temperature structural materials, nickel-base superalloys exhibit unique high temperature properties, which make them the first choice in demanding applications such as the hot sections of turbine engines for both aircraft and power-generation applications. Nickel-base superalloys rely upon a combination of matrix strengthening and precipitation hardening to give outstanding high-temperature mechanical properties. This research project will study the effect of gamma prim precipitate distribution on the deformation mechanisms in advanced gamma (matrix)/gamma prime (precipitates) nickel-base superalloys for high temperature applications. It takes an interdisciplinary approach, combining detailed metallurgical studies, in-situ mechanical testing on neutron and high-energy x-ray synchrotron diffraction beam lines and mathematical modelling. Instead of studying macroscopic mechanical properties as a function of microstructure, our approach will allow us to study directly strengthening mechanisms as a function of microstructure. In advanced superalloys, fundamental studies have often been limited by the complexity of the microstructure. We will overcome this by first studying simplified model microstructures and using these to validate and tune advanced models, before moving on to commercially more relevant but also more complex microstructures.This project will provide an improved fundamental understanding of the interplay of gamma prim-distribution and deformation mechanisms, which is key to harnessing the full potential of these new high temperature alloys. Although a number of new gamma prim strengthened polycrystalline nickel-base alloys have recently emerged from worldwide development programs, the optimisation of the mechanical properties of these alloys through thermomechanical processing has been, to date, strongly empirical. This new understanding will make it possible to identify optimum microstructures, which will not only help definite the ideal thermomechanical processing routes for newly developed alloys, but also illuminate future alloy development.