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补充了常用的合金设计经验方法是过时的，不再需要。传统上，冶金应用（例如运输、发电和建筑行业）所需的合金是使用经验法则设计的，重点放在试错程序和实验评估上。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（一种新合金的设计和鉴定可能需要长达十年的时间）和费用（大量试验合金的制造和测试）。我们将使用计算方法设计一种新的合金，它适用于最苛刻的应用之一：用于为民用飞机提供动力的燃气涡轮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性：(1)在高温下长时间使用时应保持热力学稳定；(2)在操作过程中应耐与用于保护它的保护涂层相互扩散而发生的降解反应；(3)它必须能够通过铸造制造，从而在部件制造过程中耐熔体相关缺陷的形成。数值模拟工作将在不同的尺度上进行。首先，原子方法将用于确定合金添加物的组合，这些添加物会促进电子相（如mu和sigma）的形成，从而损害蠕变和疲劳等关键性能。其次，微观结构建模将用于模拟这些系统中发生的相组合和位错降解反应的动力学演变，使用相场法等技术。第三，在连续尺度上建模将用于评估由新合金制造的部件的性能，例如，如果在铸造厂铸造，它是否容易形成铸造缺陷。我们将为这个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，一旦这个项目完成，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 modellingtools complement the commonly-employed, empirical approach to alloy design is out-dated and no longer necessary. 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.