High-throughput experimental and Calphad screening of CCAs (Hi-TeCC) - towards new alloys with exceptional mechanical properties

在过去的13年中，多主元素合金（mpea）的发展为新型材料的设计打开了新的机会之窗。mpea可分为单相高熵合金（HEAs）和多相复合合金（CCAs）。mpea不是构成一个基本元素，而是包含五个或更多的主元素。因此，可能的化学成分和性质有了很大的空间，这刺激了该领域的深入研究。然而，由于可能的合金体系数量非常多，到目前为止只能研究一小部分。更令人担忧的是，大多数可能适用于结构应用的单相无序HEAs具有无法与现有钢和镍基合金竞争的机械性能。因此，从单相HEAs到多相CCAs的沉淀/多相硬化是提高合金力学性能的一条很有前途的途径。这为迄今为止尚未开发的机会开辟了广阔的领域。为了探索和优化利用HEAs和CCAs，将高通量热力学模拟和实验相结合的广泛的合金筛选方法是不可避免的。这个建议描述了一个研究策略，满足上述问题。它也非常适合并有助于SPP 2006“成分复杂合金-高熵合金”的目标。我们将使用一种方法，允许高通量计算和实验筛选HEAs/ cca，并简化新合金系统的设计。热力学模型将包括数据库的开发和单独三元系统的评估，作为可靠的calphhad计算的基础。将从calphhad数据中确定合适的化学成分，以开发有前途的多相CCAs。利用激光金属沉积（LMD）快速发展元素粉末共混物的合金，将实现高通量生产具有高化学均匀性的大块材料。通过第一步筛选确定的有前途的合金将进行深入筛选，通过全面表征微观组织演变和力学性能。最后，最有前途的合金也将通过铸造、轧制和退火等传统工艺来生产，以证明大批量生产的可行性。我们将专注于Co-Cr-Fe-Mn-Ni体系，并添加Al和/或C来扩展该合金体系，并允许从单相HEAs推进到多相CCAs。一方面，这种方法将使我们能够建立一个更好的基本热力学描述，并对影响HEAs和CCAs力学性能的微观结构特征有一个基本的了解。另一方面，HEAs向cca的扩展使基于HEAs概念的新型先进结构材料的设计标准的面向应用的评估成为可能。

During the past 13 years a new window of opportunity for the design of novel materials was opened by the development of alloys with multi principal elements (MPEAs). MPEAs can be subdivided into single-phase high-entropy alloys (HEAs) and multi-phase compositionally complex alloys (CCAs). Instead of constituting one base element, MPEAs contain five or more principal elements. Hence, a vast space of possible chemical compositions and properties became available, which stimulated intensive research in this field. However, due to the very high number of possible alloy systems, only a small fraction could be investigated so far. Even more alarming, most single-phase, disordered HEAs potentially suitable for structural applications have mechanical properties that cannot compete with established steels and Ni-base alloys. Therefore, precipitation/multi-phase hardening by advancing from single-phase HEAs to multi-phase CCAs is a promising path to improve the mechanical properties of these alloys. This opens a vast field of hitherto unexplored opportunities. In order to explore and make optimal use of HEAs and CCAs, an extensive alloy screening approach, combining high-throughput thermodynamic simulations and experiments is inevitable. This proposal describes a research strategy that meets the issues mentioned above. It also fits and contributes very well to the objectives of the SPP 2006 "Compositionally Complex Alloys - High Entropy Alloys". We will use a methodology that allows high-throughput computational and experimental screening of HEAs/CCAs and facilitates easier design of new alloy systems. Thermodynamic modeling will include development of databases and evaluation of individual ternary systems as a basis for reliable Calphad calculations. Suitable chemical compositions will be determined from Calphad data in order to develop promising multi-phase CCAs. High-throughput production of bulk material with high chemical homogeneity will be performed by rapid alloy development using laser metal deposition (LMD) of elemental powder blends. Promising alloys identified by the first screening step will be subjected to deep screening by thorough characterization of the microstructure evolution and mechanical properties. Finally, the most promising alloy will also be produced following conventional processing by casting, rolling, and annealing to prove producibility in large quantities. We will focus on the Co-Cr-Fe-Mn-Ni system with additions of Al and/or C to extend this alloy system and allow for advancing from single-phase HEAs to multi-phase CCAs. On the one hand, this approach will allow us to develop a better fundamental thermodynamic description and gain a basic understanding of the microstructural features that influence the mechanical properties of HEAs and CCAs. On the other hand, the extension of HEAs towards CCAs enables an application-oriented assessment of design criteria for new advanced structural materials based on the concepts of HEAs.