Development of strain tolerant aluminia scasles on MCr-AL-Basis high temperatur alloys and coatings

最近的研究结果表明，在MCrAl型(M=Fe，Ni/CO)合金和涂层上，保护性氧化铝膜的抗剥落性能主要取决于氧化膜的微观结构，因为含有微结构缺陷的氧化膜，如纳米级的气孔和裂纹，往往比无垂直缺陷的均匀氧化铝膜具有更高的断裂韧性。通过改变少量合金(涂层)的成分和采用适当的表面处理，可以在很大程度上控制氧化物的组织。在拟议的项目中，将定量评估后一种参数对氧化铝鳞片中氧化物晶粒度和气孔形成的影响。建立了氧化膜的显微组织、等温氧化动力学和断裂韧性之间的定量关系。标尺特性将通过一系列分析技术来表征，重点是定量的扫描电子显微镜研究和光谱应力测量。从这些研究中获得的知识可以用来指导开发具有更长使用寿命的MCrAl型合金(涂层)。

Recently available results indicate that spallation resistance of the protective alumina scales on MCrAl-type (M=Fe, Ni/CO) alloys and coatings crucially depends on the scale microstructure because scales containing microstrutural defects, such as nano-sized pores and cracks often exhibit a higher fracture toughess, than virtally defect-free, uniform alumina films. The oxide microstructure can, to a large extent be controlled by modifying the minor alloy (coating) composition and by using suitable suface pre-treatments. In the proposed project the effect of the latter parameters on the oxide grain size and porosity formation in the alumina scales will be quantitatively assessed. A quantitative correlation between the oxide microstructure, isothermal oxidation kinetics and fracture toughness of the formed scales will be derived. The scale properties will be characterised by a range of analytical techniques with emphasis on quantitative SEM studies and piesospectroscopic stress measurements. The knowledge derived in these studies can be used as a guideline for development of MCrAl-type alloys (coatings) with extended service lives.