Tailored precipitation (B2, L21) strengthened, compositionally complex FeAlCr (Mn, Co, Ni, Ti) alloys for high temperature applications

适用于高温应用的定制沉淀 (B2、L21) 强化、成分复杂的 FeAlCr（Mn、Co、Ni、Ti）合金

• 批准号: 388541188
• 负责人: Professor Dr. Christian Liebscher
• 金额: --
• 依托单位: Lehrstuhl für Werkstoffchemie (MCh)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/388541188?language=en
• 关键词: Tailored; precipitation; B2; L21; strengthened

High entropy alloys (HEAs) or compositionally complex alloys (CCAs) are multicomponent systems with typically more than five alloying elements. The large compositional space offers attractive alloy design strategies and initially it was assumed that by maximizing the entropy of mixing, true single phase solid solutions can be established. However, only very few successful single phase alloys could be obtained in the past 10 years of HEA development and in the majority of cases multi-phase microstructures, including intermetallic phases, form. However, such multi-phase alloy systems could yield alloys bridging the enormous gap between Titanium and Nickel-based alloys in terms of alloy density and application temperature, but this application field is rarely explored.The aim of the present work is to develop body-centered cubic (BCC) CCAs with tailored precipitates based on B2- and/or L21-phases with densities of < 7 g/cm3 for high temperature applications up to 900ºC. In a first step, the phase formation in the rather unexplored composition space of FeAlCr (Mn, Co, Ni, Ti) is explored by high throughput screening and characterization based on thin film deposition techniques. Promising alloy candidates are identified fulfilling the conditions to have a BCC crystal structure and showing either B2, L21 or both types of precipitate phases. In further steps, these alloy candidates are then obtained by conventional casting techniques to investigate the microstructure and precipitate structure in as-cast alloys and to evaluate their high temperature stability after thermal exposure of up to 900ºC. The alloy design approach is based on a microstructural optimization in terms of precipitate morphology, coherency with the supersaturated BCC matrix and their volume fraction. Tailored microstructures are then mechanically tested from room up to temperatures of 900ºC to establish the microstructure-property relationship for further optimization steps. In addition, first high temperature creep experiments give insights into the microstructural stability at elevated temperatures under load and the operating deformation mechanisms.The microstructural characterization and mechanical property evaluation throughout the alloy design process are cornerstones of the presented research. The combination of mechanical testing with advanced characterization techniques such as X-ray diffraction, transmission electron microscopy and atom probe tomography is guiding the development of these novel alloy systems from a mesoscopic length scale down to the atomic scale.

高熵合金（HEAS）或合成复杂的合金（CCA）是多组分系统，通常具有五个以上的合金元素。较大的复合空间提供了有吸引力的合金设计策略，最初可以假定，可以最大程度地提高混合的熵，真正的单相固体解决方案。但是，在过去10年的HEA发育中，只能获得很少的成功单相合金，在大多数情况下，多相微结构（包括金属间阶段）形式。但是，这种多相合金系统可以产生合金，从而在合金密度和施用温度方面弥合钛和基于镍的合金之间的巨大差距，但是很少探索该申请领域。当前工作的目的是基于B2--和/或l21-l21-sess of Bodent Coarties of Bodent Bodent Bodent Codisties of Body Codies of Bodent Codies ccas的目的，而<7 GAR和/或l21-l21- plote <g。 900ºC。第一步，通过基于薄膜沉积技术的高吞吐量筛选和表征，探索了FEALCR（MN，CO，NI，TI）的相当意外组成空间中的相位形成。有希望的合金候选物可以满足其具有BCC晶体结构并显示B2，L21或两种类型的精确阶段的条件。在进一步的步骤中，通过常规铸造技术获得这些合金候选物，以研究铸造合金中的微观结构和珍贵结构，并评估其热暴露于900ºC后的高温稳定性。合金设计方法是基于微结构优化的，就沉淀的形态，与过饱和BCC矩阵的相干性及其体积分数相干。然后，将量身定制的微观结构从房间到900ºC的温度进行机械测试，以建立微观结构 - 托管关系以进行进一步的优化步骤。此外，第一个高温蠕变实验可以深入了解载荷下高温和操作变形机制下的微观结构稳定性。整个合金设计过程中的微结构表征和机械性能评估是提出的研究的基础。机械测试与先进特征技术（例如X射线衍射，透射电子显微镜和原子探针层析成像）的组合正在指导这些新型合金系统从介质长度尺度到原子尺度的开发。