Directional solidification of multiphase metallic high temperature materials beyond Ni-base superalloys

镍基高温合金以外的多相金属高温材料的定向凝固

基本信息

批准号：
171451837
负责人：
Professor Dr.-Ing. Martin Heilmaier
金额：
--
依托单位：
Institut für Angewandte Materialien - Werkstoffkunde (IAM-WK)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/171451837?language=en
关键词：
Directional solidification multiphase metallic temperature

项目摘要

Major goal of this project is to determine the influence of directional solidification (DS) on the mechanical properties of alloy systems exhibiting melting points far beyond Nickel based superalloys (e.g. Nb-Si-Cr and Mo-Si-Ti). As soon as the zone melting device had been put into service by using the reference binary eutectic alloy Nb-18 at% Si, the obtained knowledge was transferred to the three-phase system Nb-Si-Cr and to the two-phase system Mo-Si-Ti. A direct correlation between solidification parameters and the resulting microstructure was obtained. Regarding the high temperature creep properties, DS of Nb-18 at% Si led to a significantly increased creep resistance (about three orders of magnitude better), as compared to a powder metallurgically produced alloy. This difference can mainly be attributed to the different size of microstructural features, the predominant mechanism being diffusional creep in both materials. A comparison with a state of the art single-crystalline Nickel based superalloys (CMSX 4) underpins the outstanding improvement of the creep resistance of DS NbSi eutectics. First creep results for DS ternary Nb-Si-Cr alloys indicate dislocation creep to be the rate controlling mechanism. The observed increase of the stress exponent with decreasing stress can be rationalized by the formation of nanoscaled NbCr2 precipitates. Unexpectedly, the arc melted reference alloy, exhibits superior creep resistance. In the second phase of the project, phase field simulations will be continued at the binary Nb-Si in 3D, involving anisotropic interfacial energies derived from atomistic models. Through simulation studies, an understanding of the spatial composition of the lamellar structure is obtained in 3D and the influence of potential nucleation events is analyzed. In parallel, a deeper understanding of the creep behavior observed in the ternary system Nb-Si-Cr will be developed. Also, the determination of the ductile-brittle transition temperature (DBTT) and the oxidation properties is a major task of this project. Besides experimental identification of the ternary-eutectic point, the phase field modelling will be extended to the ternary Nb-Si-Cr system. For two thermodynamic models based on Pandat data and on experimental results, 3D microstructure simulations will be performed. Phase arrangements and microstructural parameters will be comparatively assessed, and the morphologies will be categorized. Based on own literature data, the alloying element Vanadium will be added to the Nb-Si-Cr system, as it potentially improves fracture toughness and oxidation resistance. In the system Mo-Si-Ti an optimum composition regarding the possibility of directional solidification, has to be identified. Finally, selected creep tests will be performed to compare the influence of the generated microstructures.

该项目的主要目标是确定方向固化（DS）对远远超出镍基超合金（例如NB-SI-CR和MO-SI-TI）的合金系统机械性能的影响。一旦使用参考二进制共晶合金NB-18 AT％Si进行了熔化设备，将获得的知识转移到三相系统NB-SI-CR和两阶段的Mo-Si-Ti中。获得了固化参数与所得的微观结构之间的直接相关性。关于高温蠕变性能，与粉末冶金产生的合金相比，NB-18 AT％Si的DS导致蠕变耐药性显着增加（大约三个数量级）。这种差异主要归因于微观结构特征的不同大小，这是两种材料的扩散机制。与最先进的单晶镍的超级合金（CMSX 4）进行了比较，这是DS NBSI Eutectics的蠕变抗性的出色改善。 DS三元NB-SI-CR合金的第一个蠕变结果表明位错蠕变是速率控制机制。观察到的应力指数随压力减少而增加的增加可以通过纳米NBCR2沉淀物的形成来合理化。出乎意料的是，ARC熔化的参考合金具有出色的蠕变抗性。在项目的第二阶段中，相位场模拟将在3D的二进制NB-SI处继续，涉及来自原子模型的各向异性界面能量。通过模拟研究，在3D中获得了对层状结构的空间组成的理解，并分析了潜在成核事件的影响。同时，将对在三元系统NB-SI-CR中观察到的蠕变行为有更深入的了解。同样，确定延性 - 脆性过渡温度（DBTT）和氧化特性是该项目的主要任务。除了对三元 - 切正确点的实验鉴定外，相位场建模还将扩展到三元NB-SI-CR系统。对于基于PANDAT数据和实验结果的两个热力学模型，将进行3D微观结构模拟。相对评估的相位布置和微结构参数将进行比较，并将分类。根据自己的文献数据，将添加到NB-SI-CR系统中的合金元素钒，因为它可能会改善断裂韧性和氧化耐药性。在系统中，必须确定有关定向固化可能性的最佳组成。最后，将进行选定的蠕变测试，以比较生成的微观结构的影响。