Process modelling to improve materials properties and microstructure for aerospace applications

拟议的研究计划是基于材料科学中先进材料的加工和制造过程的操作参数与其产生的微观结构和机械/物理性能之间的关系。为了优化特定应用的材料性能，始终有必要了解材料微观结构的演变（晶粒尺寸，孔隙率，偏析，相分布，加工硬化等），以仔细控制加工步骤的操作参数（温度，应变速率，冷却速率，压力等）。建立不同条件下材料转化的物理模型以确定主要驱动参数是十分重要的。然后，可以在有限元分析工具中实现模型，以预测不同点的所得微观结构和零件的期望性能。对于目前的建议，我们将集中精力对航空航天工业中使用的高温部件制造的先进工艺的具体步骤进行建模。研究计划的主要目标是：1)确定对所得材料微观结构有重大影响的工艺参数；2)模拟材料在加工条件下的物理行为；3)通过数值模拟确定给定应用中材料微观结构与目标功能性能之间的关系。该研究方法将应用于：1)确定镍高温合金涡轮叶片电子束焊接过程中产生热裂纹的条件；2)采用基于纤维增强聚合物复合材料树脂转移模塑的专利方法制备陶瓷基/陶瓷纤维复合材料。所有这些研究项目都将得到工业伙伴的部分支持。该研究项目的活动与加拿大工业在航空航天工业的先进材料和制造技术方面的高度优先领域密切相关。这些活动将导致对高性能材料的行为进行数值模拟的方法的发展，这些材料专门设计用于在高温下工作，例如涡轮发动机的热段中使用的材料。该研究的独创性是基于将数值建模应用于生产规模需要的部件制造的新工艺。为了使所选的特定高性能材料获得所需的性能，在材料加工过程中进行仔细的控制是绝对必要的。

The proposed research program is based on the relationship in materials science between the operating parameters for the elaboration and manufacturing processes of advanced materials and their resulting microstructure and mechanical/physical properties. To optimize the properties of materials for specific applications, it is always necessary to have a good knowledge of the evolution of material microstructure (grain size, porosity, segregation, phase distribution, work hardening, etc.) to control carefully the operating parameters of processing steps (temperature, strain rate, cooling rate, pressure, etc.). It is important to develop the physical modelling of materials transformation under different conditions to identify the main driving parameters. Then, it is possible to implement the models in finite element analysis tools to predict the resulting microstructure at different points and the desired properties of the parts. For the present proposal, we would concentrate the effort on the modelling of specific steps of advanced processes for the fabrication of high temperature components used in the aerospace industry. The main objectives of the research program are: 1) identify the process parameters that have a major influence in the resulting materials microstructure; 2) model the physical behavior of the materials under the processing conditions; 3) determine by numerical simulation the relation between materials microstructure and targeted functional properties for given applications. This research approach will be applied to: 1) determination of conditions leading to hot crack formation during electron beam welding of turbine blades made of nickel superalloys; 2) fabrication of ceramic matrix / ceramic fibers composites by a patented methodology adapted from resin transfer moulding of fiber reinforced polymer composites. All these research projects would be partly supported by industrial partners. The activities of the research program are strongly related to the highly prioritized domains for Canadian industry in advanced materials and fabrication technologies for the aerospace industry. The activities will lead to the development of approaches for the numerical modelling of the behaviour of high performance materials specifically designed to operate at high temperature such as those used in the hot section of turbine engines. The originality of the research is based on the application of numerical modelling to novel processes for the fabrication of components for production scale needs. The careful control in the materials processing is absolutely necessary for the selected specific high performance materials to obtain the desired properties.