Investigation of TaC precipitation hardening in Co-Re-based alloys

co - re基合金在2007年被提出作为高温应用的候选材料。DFG研究小组for 727 Beyond ni基高温合金的化学成分、微观结构和氧化行为/力学性能之间的相互关系首次对它们进行了研究。碳化钽沉淀硬化是一种特别有吸引力的强化机制。然而，研究的深度有限，只关注一种合金成分（Co-17Re-23Cr-1.2Ta-2.6C）和相对较短的热处理周期。因此，关于碳化钽的稳定性、析出动力学和转变行为的许多问题仍然没有解决。除了传统的微观结构表征工具，原位中子散射被证明是特别有价值的，因为它允许在高温退火过程中获得代表性材料体积的晶体学和形态学信息。针对这一情况，提出了一项由布伦瑞克工业大学和梅<s:1>琛工业大学联合开展的研究计划，以深入研究碳化钽在co - re基合金中的析出机理。布伦瑞克工业大学的双光束显微镜三维断层扫描将作为显微结构表征的重要工具，与梅<s:1>琛工业大学的Heinz Maier-Leibnitz中子源一起使用。总体目标是探索合金成分、热载荷和碳化钽析出行为之间的相互关系，为充分挖掘碳化钽在co - re基合金高温应用中的强化潜力提供必要条件。

Co-Re-based alloys have been proposed in 2007 as candidate materials for high temperature applications. They were investigated for the first time in the DFG research group FOR 727 Beyond Ni-Base Superalloys with respect to the interrelation between chemical composition, microstructure and oxidation behavior / mechanical properties, respectively. Precipitation hardening by tantalum carbides (TaC) was identified as particularly attractive strengthening mechanism. Yet, the depth of investigation was limited, focusing on one alloy composition only (Co-17Re-23Cr-1.2Ta-2.6C) and relatively short heat treatment cycles. Therefore, many questions regarding stability, precipitation kinetics and transformation behavior of the tantalum carbides remained open. Besides conventional microstructural characterization tools, in-situ neutron scattering turned out to be particularly valuable as it allows to gain crystallographic and morphological information for representative material volumes during high temperature annealing. In view of this situation a joint research program involving TU Braunschweig and TU München is proposed to thoroughly investigate the precipitation mechanism of tantalum carbides in Co-Re-based alloys. 3D tomography by dual beam microscopy at TU Braunschweig will be used besides the Heinz Maier-Leibnitz neutron source at TU München as essential tool for microstructural characterization. Overall objective is to explore the interrelationship between alloy composition, thermal loading and precipitation behavior of the tantalum carbides as necessary condition to fully exploit the strengthening potential of tantalum carbides during high temperature application of Co-Re-based alloys.