Coarsening and growth of meta-stable gamma''-precipitates in Nickel-base Superalloys

该项目的目的是研究相场建模方法，以模拟ni基模型合金中的γ -沉淀，并辅以各自的实验特征。中心目标是研究相场建模方法在选定载荷条件下对γ " -沉淀生长以及随后粗化的动力学的预测能力。相场预测的实验参考将是高质量的实验微观结构数据，在项目中生成。在相应的实验研究中，我们计划定量测量一系列不同样品的γ -颗粒的大小和形状，这些样品在不同的时间在选定的载荷下老化，涵盖了从最初的沉淀生长到γ -粗化的整个时间范围。该项目的主要目标是通过实验研究γ " -粒子的沉淀硬化机制，这对于理解高温ni基变形合金（如IN718）的硬度具有重要的基础意义。与γ′-颗粒相反，γ′-相以三种不同的取向变体存在，导致载荷下相当复杂的粗化行为。γ " -粒子的生长和随后的粗化背后的基本物理机制涉及材料的溶解化学和微观相结构的热力学之间的强耦合。根据优先计划的目标，该项目的科学关键目标是推动相场建模作为一种技术，在微观水平上解决这种热-化学-力学相互作用，在冶金和材料科学背景下具有更好的实际可用性。

The aim of the project is to study phase field modelling approaches for the simulation of gamma''- precipitation in a Ni-base model alloy, assisted by respective experimental characterisations.The central goal is to investigate the predictive power of the phase field modelling approache with respect to the kinetics of gamma''- precipitation growthas well as subsequent coarsening under selected loading conditions.The experimental reference for the phase field predictions will be high quality experimental microstructure data, generated within the project. In corresponding experimental investigations, we plan to quantitatively measure the sizes and shapes of the gamma''- particles for a series of different samples, aged under selected loadings at different times, covering the whole time range from the initial precipitation growth right into the gamma''- coarsening regime.A primary goal of the project is to experimentally investigate the mechanism of precipitation hardening of gamma''- particles only, which is of high fundamental relevance for the understanding of the hardness in high temperature Ni-base wrought alloys such as IN718. In contrast to gamma'- particles, the gamma''- precipitates exist in three different orientational variants, leading to a quite complex coarsening behaviour under load. The elementary physical mechanisms behind the growth and subsequent coarsening of gamma''- particles involve a strong coupling between the materials solutal-chemistry and the thermo-mechanics of the microscopic phase structure.According to the goals of the Priority Programme, it is a scientific key goal of the project to push forward phase field modelling as a technique, which resolves this thermo-chemo-mechanic interplay on a microcopic level, towards a better practical usability in a metallurgical and materials scientific context.