Alloys By Design - A Materials Modelling Approach

有了这个建议，我们将使用现代冶金建模工具来证明最先进的现代冶金建模工具可以补充通常使用的合金设计的经验方法。传统上，冶金应用(例如，交通、发电和建筑行业)所需的合金都是使用经验法则设计的，强调试错程序和通过实验进行评估。基于计算机的方法的应用将减少与合金设计过程相关的时间(一种新合金可能需要长达十年的设计和鉴定)和费用(大量试验合金被制造和测试)。我们将设计一种新的合金-使用计算方法-适合于最苛刻的应用之一：为民用飞机提供动力的燃气轮机发动机最热部件所需的涡轮叶片。新合金的设计理念要求它具有三个关键特征：(I)它应该在高温下的较长时间内保持热力学稳定；(Ii)它应该能够抵抗在运行过程中与用于保护它的保护层相互扩散而发生的降解反应；(Iii)它必须能够通过铸造来制造，从而防止在部件制造过程中形成与熔体有关的缺陷。数值模拟工作将在不同的尺度上进行。首先，将使用原子学方法来确定合金化添加的组合，这些添加促进了电子相的形成，如u和sigma，而这些相损害了蠕变和疲劳等关键性能。第二，微结构模型将被用来模拟在这些系统中发生的相组合和位错退化反应的动力学演化，使用诸如相场方法等技术。第三，将使用连续体尺度上的建模来评估由新合金制成的部件的性能，例如，如果在铸造厂铸造，它是否容易形成铸造缺陷。我们将为该项目开发的建模工具将在冶金和材料科学领域具有相当大的通用性，因此，一旦该项目完成，我们将能够使用它们来设计其他冶金系统。

With this proposal, we will use modern metallurgical modelling tools to demonstrate that state of the art modern metallurgical modelling tools can complement the commonly-employed, empirical approach to alloy design. Traditionally, alloys required for metallurgical applications (e.g. within the transportation, power generation and construction industries) have been designed using rules-of-thumb, with emphasis placed on trial-and-error procedures and assessment by experiment. Application of computer-based methods will reduce the time (a new alloy can take up to ten years to design and qualify) and expense (a large number of trial alloys are fabricated and tested) which are associated with the alloy design process. We will design a new alloy - using computational methods - which is suitable for use in one of the most demanding applications: the turbine blading needed for the hottest parts of the gas turbine engine used for powering civil aircraft. The design concept for the new alloy requires it to have three key characteristics: (i) it should be thermodynamically stable during extended periods of service at high temperatures (ii) it should be resistant to degradation reactions which occur by interdiffusion with protective coatings used to protect it during operation and (iii) it must be capable of being fabricated by casting and thus resistant to the formation of melt-related defects during component fabrication. The numerical modelling work will be carried out at various scales. First, atomistic methods will be used to identify the combination of alloying additions which promote the formation of electron phases such as mu and sigma which impair key properties such as creep and fatigue. Second, microstructural modelling will be used to simulate the kinetic evolution of phase assemblies and dislocation degradation reactions which occur in these systems using techniques such as the phase field method. Third, modelling on the continuum scale will be used to assess how a component fabricated from the new alloy will perform, e.g. whether it would be prone to the formation of casting defects if it were to be cast in the foundry. The modelling tools which we will develop for this project will have considerable generality in the field of metallurgy and materials science and consequently, once this project is finished we will be in a position to use them for designing other metallurgical systems.