Development of Theory and Technique to Measure a Triple Junction Distribution Function (3DF)

测量三结分布函数 (3DF) 的理论和技术的发展

• 批准号: 1003004
• 负责人: David Field
• 金额: $ 34.56万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1003004&HistoricalAwards=false
• 关键词: Development; Theory; Technique; Measure; Triple

TECHNICAL SUMMARY: This research ultimately aims at developing a more complete understanding of triple junction character and how the geometric character of the triple junction relates to the observed properties and local character of the microstructure. A triple-junction distribution function (3DF) will be developed that characterizes the complete space of triple junctions without assuming a priori that a certain type of boundary or junction is special. 3DF measurements will be obtained using grain-boundary engineered Cu and the Inconel alloys 600 and 617. The 3DF will include the functional dependence on crystallite lattice misorientations, triple line orientations with respect to the lattice and grain-boundary plane orientations. The complete function lies in an extremely large space making statistically reliable measurements difficult to obtain. This problem will be overcome by focusing on triple junctions associated with twin boundaries, thereby reducing the dimensionality of the function. The proposed analysis applies specifically to grain-boundary engineered alloys that have a preponderance of coherent twins, but the technique can be easily extended to include all triple junctions. Microstructural characterization to this extent has yet to be employed in investigations of grain-boundary engineering and offers a real opportunity to gain a more complete understanding of the mechanisms involved in formation of triple junctions. Finally, carbide and void distributions in alloy 617 will be characterized using the 3DF.NON-TECHNICAL SUMMARY: Polycrystalline materials subjected to stress at high temperatures for long periods of time often develop brittle phases or even voids and cracks in certain regions that are most susceptible to this type of microstructural damage. Such materials are used in conventional fossil-fuel and nuclear power plants, for example, and these alloys are the primary focus of this project. To be able to predict the lifetime of such materials, the distribution of grain boundaries and their intersections (triple junctions), where damage is most likely to occur, should be quantified. To this end, the difficulty in measuring triple-junction distributions has prevented reliable characterization of these features in real materials. The present work focuses on the development of a triple junction distribution function that will enable researchers to properly characterize regions that are most susceptible to damage and distinguish them from those that are least susceptible. With this information, more realistic predictions of the useful life of engineering materials can be made, and process engineers will be able to design fabrication procedures that result in the most damage resistant microstructures. Undergraduate and graduate students will be involved through experience in the laboratory and development of curriculum.

技术概要：本研究的最终目的是开发一个更完整的理解三重连接的字符和三重连接的几何特征如何与所观察到的性能和局部特征的微观结构。一个三重结分布函数（3DF）将开发的特点是完整的空间的三重结，而不假设先验的某种类型的边界或结是特殊的。3DF测量将使用晶界工程Cu和Inconel合金600和617获得。3DF将包括功能依赖于微晶晶格取向差，三线取向相对于晶格和晶界平面取向。 完整的功能在于一个非常大的空间，使得难以获得统计上可靠的测量。这个问题将通过关注与孪晶边界相关的三重连接来克服，从而减少函数的维数。所提出的分析特别适用于晶界工程合金，具有优势的相干孪晶，但该技术可以很容易地扩展到包括所有的三重结。微观结构的表征，在这种程度上还没有被采用的晶界工程的调查，并提供了一个真实的机会，以获得更完整的理解的机制，在形成三重连接。最后，将使用3DF来表征合金617中的碳化物和空隙分布。非技术总结：在高温下长时间承受应力的多晶材料通常会在某些最容易受到这种影响的区域产生脆性相，甚至空隙和裂纹。类型的微观结构损伤。例如，这些材料用于传统的化石燃料和核电站，这些合金是该项目的主要重点。为了能够预测这种材料的寿命，应该量化最可能发生损坏的晶界及其交叉点（三重连接点）的分布。为此，在测量三结分布的困难，阻碍了可靠的表征这些功能在真实的材料。目前的工作重点是开发一个三重连接分布函数，使研究人员能够正确表征最容易受到损害的区域，并将它们与最不容易受到损害的区域区分开来。有了这些信息，可以对工程材料的使用寿命进行更现实的预测，工艺工程师将能够设计出最抗损伤的微结构的制造程序。本科生和研究生将通过实验室和课程开发的经验参与。