A High-Throughput Computational and Experimental Approach to the Design of Multi-Principal Element Alloys

为了满足下一代高性能运输和能源系统的设计要求，需要发现和开发具有最佳性能组合的新金属材料。从历史上看，金属合金的发展集中在通过添加少量其他元素来修改具有一种主要元素（例如铝或钛）的合金。这种策略忽略了由几种元素以大致相等的分数组成的合金所代表的巨大设计空间。由于在该设计空间内存在数百万种组合，因此使用传统的试错法来识别感兴趣的特定成分以进行合金开发将非常耗时且昂贵。需要一种快速和廉价的方法来有效地筛选可能的候选组合物。该项目使用计算机模拟来识别具有改善性能潜力的元素组合，然后只制造最有前途的组合以供进一步考虑。为了进一步降低成本，使用先进的基于3D打印的合成方法来构建由大约100种不同成分组成的紧凑材料库。合金库的构建在几分钟内完成，仅使用几克材料。筛选文库以鉴定具有强度、密度、成本或其它性质的最佳组合的特定组合物。这种“高通量”的金属合金设计方法将大大提高效率，降低发现和优化新的高性能金属材料所需的成本。此外，该项目还将通过针对不同学区的初中和高中教师的研讨会，促进科学和工程劳动力队伍的发展，培训他们掌握计算和高效制造方法，并影响K-12科学和工程教育。和能量储存装置需要发现和开发具有增强性能的新结构合金。多主元素合金（MPEAs），由几个组成元素，但没有占主导地位的溶剂物种，代表了一个巨大的，但开发不足的设计空间，由于传统的合金设计方法耗时的性质。这个合作项目的目的是调查的化学组成的作用，具有一个占主导地位的BCC相的MPEAs的相稳定性和机械性能，使用高通量的方法。该项目集成了第一原理密度泛函理论（DFT）计算和最先进的基于激光沉积的合成，以快速发现具有理想的强度，密度，熔化温度和成本组合的MPEAs。局部结构的特点是使用像差校正扫描透射电子显微镜成像和光谱，结合DFT计算来阐明的作用，构型熵，混合焓，晶格应变和其他因素的相稳定性。在组合物的机械性能的变化，其特征在于使用纳米压痕和其他微观力学方法和相关的结构，以开发适当的结构-性能模型。具有最有前途的微观性能的合金将被批量制备，用于进一步的分析和模型验证。通过对多组分设计空间的全方位快速评估，该项目有可能加深科学界对这些复杂合金的理解，并识别出具有大幅改进和意想不到的性能组合的新材料。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Non-technical AbstractMeeting the design requirements of the next generation of high performance transportation and energy systems requires the discovery and development of new metallic materials with optimal combinations of properties. Historically, the development of metallic alloys has focused on modifying alloys with one dominant element, such as aluminum or titanium, by adding small percentages of other elements. This strategy neglects the vast design space represented by alloys consisting of several elements in roughly equal fractions. Because many millions of combinations exist within this design space, identifying specific compositions of interest using conventional trial-and-error approaches to alloy development would be very time-consuming and expensive. A rapid and inexpensive method for efficiently screening the possible candidate compositions is required. This project uses computer simulations to identify combinations of elements with the potential for improved properties, and then manufactures only the most promising combinations for further consideration. To further reduce costs, an advanced 3D printing-based synthesis method is used to construct compact material libraries consisting of approximately 100 distinct compositions. The alloy library construction is accomplished in minutes, using only a few grams of material. The libraries are screened to identify the specific compositions with the best combinations of strength, density, cost, or other properties. This 'high-throughput' approach to metal alloy design will dramatically increase efficiency and reduce the cost required to discover and optimize new high performance metallic materials. Furthermore, the project will contribute to development of a science and engineering workforce trained in computational and efficient manufacturing methods, as well as impact K-12 science and engineering education through workshops targeting middle and high school teachers from diverse school districts.Technical AbstractMeeting the design requirements of the next generation of high performance transportation systems, power generators, and energy storage devices requires the discovery and development of new structural alloys with enhanced properties. Multi-principal element alloys (MPEAs), consisting of several constituent elements but no dominant solvent species, represent a vast yet under-explored design space due to the time-consuming nature of traditional alloy design methods. The objective of this collaborative project is to investigate the role of chemical composition on the phase-stability and mechanical properties of MPEAs having a dominant BCC phase using a high-throughput approach. The project integrates first-principles density-functional theory (DFT) calculations and state-of-the-art laser deposition-based synthesis to rapidly discover MPEAs with desirable combinations of strength, density, melting temperature, and cost. The local structure is characterized using aberration-corrected scanning transmission electron microscope imaging and spectroscopy, which are combined with DFT calculations to elucidate the roles of configurational entropy, mixing enthalpy, lattice strains and other factors on phase stability. Variations in the mechanical properties with composition are characterized using nanoindentation and other micromechanical methods and correlated with the structure in order to develop appropriate structure-property models. Alloys with the most promising microscale properties will be prepared in bulk for further analysis and model validation. By enabling rapid evaluation over the full breadth of the multicomponent design space, the project has the potential to deepen the scientific community's understanding of these complex alloys and identify new materials with vastly improved and unexpected combinations of properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.