Microstructural stability and creep of elevated temperature alloys

高温合金的微观结构稳定性和蠕变

• 批准号: 155210-2006
• 负责人: Beddoes, Jonathan
• 金额: $ 2.55万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2006
• 资助国家: 加拿大
• 起止时间: 2006-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=331563
• 关键词: Microstructural; stability; creep; elevated; temperature

Creep refers to time dependent strain - or slow shape change during extended periods of loading. Creep deformation and failure afflicts many elevated temperature applications of engineering materials, such as gas turbine engine components and many heat exchanger structures. Undertaking laboratory creep tests is relatively straightforward, but understanding the physical metallurgical factors controlling creep as a function of the applied temperature and load is much more challenging. Several theories to explain the creep of metallic crystalline structures have been developed which rely on the response of crystalline defects and crystal grain boundaries to explain the accummulation of strain during creep. The research proposed will systematically investigate the influence of grain boundary structure on the primary creep response of three alloys designed for use at elevated temperatures. In particular, the grain boundary structure will be modified from 'planar' to 'serrated' morphologies. It is reasonably well established that serrated boundaries delay creep failure by hindering the growth of creep cracks along boundaries that are normal to the main loading direction. However, very little is understood regarding the influence of grain boundary morphology on the primary creep behaviour - the initial period during which the rate of strain accummulation continuously decreases. For many engineering applications the duration of primary creep determines component service life. The result of this research will be an improved understanding of the factors controlling creep of engineering alloys. This understanding can be applied to the microstructural design of alloys with improved creep resistance.

蠕变是指与时间相关的应变 - 或在长时间加载期间缓慢的形状变化。蠕变变形和失效影响工程材料的许多高温应用，例如燃气涡轮发动机部件和许多热交换器结构。进行实验室蠕变测试相对简单，但了解控制蠕变的物理冶金因素作为所施加温度和载荷的函数则更具挑战性。已经开发了几种解释金属晶体结构蠕变的理论，这些理论依赖于晶体缺陷和晶粒边界的响应来解释蠕变过程中应变的积累。拟议的研究将系统地研究晶界结构对三种高温下使用的合金的初级蠕变响应的影响。特别是，晶界结构将从“平面”形态修改为“锯齿状”形态。众所周知，锯齿状边界通过阻碍蠕变裂纹沿着垂直于主载荷方向的边界生长来延迟蠕变失效。然而，关于晶界形态对初级蠕变行为（应变累积速率持续降低的初始阶段）的影响，人们了解甚少。对于许多工程应用来说，初级蠕变的持续时间决定了部件的使用寿命。这项研究的结果将加深对控制工程合金蠕变的因素的理解。这种理解可以应用于具有改进的抗蠕变性的合金的微观结构设计。