第一性原理设计和筛选高性能钴基高温合金

Cobalt-based superalloys are newly developed high-temperature engineering materials. They exhibit superior hot corrosion, oxidation, and wear resistance compared to conventional Ni-based superalloys. Experimental studies have shown that discovery of the γ/γ' high-temperature strengthening offered novel Co-based superalloy higher strength and higher melting temperature corresponding to Ni-based superalloys. Such excellent high-temperature properties and mechanical properties make Co-based superalloys having huge potential applications in high-performance equipments such as aircraft engines and power-generation systems, etc. To achieve excellent structural materials, it is vital to optimize alloy components and their ratios. It is rather expensive and inefficient to design alloys using traditional trial-and-error tools. The molecular dynamics methods and traditional first-principles methods are not suitable to screen the alloys. The former cannot build a connection between electronical structures and macroscopic properties due to its low accuracy, whereas the latter becomes very time-consuming in the case of multicomponent systems. However, the advanced ab initio alloy theory as formulated within the EMTO-CPA method become the ideal choice when designing and screening complex alloys. The EMTO-CPA approach can accurately describe multicomponent and multiphase complex alloys with continuously changed alloy components. The aim of this proposal is to investigate the effect of eighteen kinds of doped elements on the electronical structures of multicomponent Co-based superalloys using the EMTO-CPA method. As a starting point, we will investigate the composition and temperature dependences of the elastic moduli, micro-mechanical properties, and electronic structures of Co-based superalloys. From these results, we will be able to reveal the microscopic mechanism responsible for the observed mechanical properties of Co-based superalloys from first-principles. We will establish atomistic level databases which can be used for designing and screening high-performance novel Co-based superalloys.

钴基高温合金是新兴的高性能工程材料，它具有比常规的镍基高温合金更好的抗腐蚀、抗氧化和抗疲劳等性能，实验表明γ/γ'双相硬化机制的发现使其具有比镍合金更高的高温强度和融化温度，有望用于高精尖设备如航空发动机和发电系统等。优化合金组元及其配比是得到高性能材料的关键。实验方法耗资巨大且低效。分子模拟方法和传统的第一性原理方法都不适于筛选合金，前者精度不高，无法建立电子结构与宏观性能的关系；后者处理多元体系时非常耗时。而先进的第一性原理合金理论EMTO-CPA方法，能够精确地描述组元成分连续变化的合金，是设计和筛选复杂合金的理想工具。本项目拟采用EMTO-CPA方法，阐明18种掺杂元素对钴基高温合金的电子结构的影响，以此为出发点研究合金的弹性性能、机械性能和电子结构的成分和温度依赖性，从而在电子层面上揭示钴基高温合金的性能的微观机制，为合理设计和筛选高性能的新型钴基高温合金提供科学的理论依据。

钴基高温合金是一类高性能工程材料，它具有比常规的镍基高温合金更好的抗腐蚀、抗氧化和抗疲劳等性能，有望用于高精尖设备如航空发动机和发电系统等。优化合金组元及其配比是得到高性能材料的关键。实验方法耗资巨大且低效，分子模拟方法和传统的第一性原理方法都不适于筛选合金。先进的第一性原理合金理论EMTO-CPA方法，能够精确地描述组元成分连续变化的合金，并且可以任意调节合金的成分配比，计算的效率和准确性都很高，是设计和筛选复杂合金的理想工具。为此，本项目在已有的研究基础上，通过采用并扩展改进EMTO-CPA方法，研究合金化效应对钴基高温合金、Fe-Co二元合金、Fe-Mn-Al三元合金、AlxCrMnFeCoNi多元合金的弹性性能、机械性能和电子结构的影响规律；阐明温度效应对弹性性能的影响机制。得出以下结论：.1）通过采用EMTO-CPA方法，研究了多种掺杂元素对复杂合金的弹性性能、机械性能和电子结构的合金化效应，在电子层面上揭示了影响合金性能的微观机制，通过优化合金成分和明确各个组元的效应来合理设计和筛选合金。.2）扩展并改进现有的第一性原理EMTO-CPA方法，在EMTO中编译和引入部分局域磁矩无序模型 （Partial Disordered Local Magnetic Moment, PDLM），利用EMTO-CPA-PDLM方法来解释合金的弹性性能和机械性能的随温度变化的规律。.本项目的研究结果扩展并改进了现有的EMTO-CPA方法，引入PDLM模型，能够在第一性原理计算中考察温度效应对合金性能的影响机制，并揭示了合金成分和温度效应对合金弹性性能和机械性能的影响规律，为开发高性能复杂合金提供了理论依据。.近三年，在该项目的资助下发表SCI国际期刊论文4篇，其中包括Physical Review B 1篇、Acta Materialia 1篇、Journal of Physics: Condensed Matter 1篇、Journal of Applied Physics 1篇。培养硕、博生4名，其中毕业1名硕士生。项目组成员参加国际、国内学术交流会6人次并做口头报告，其中邀请报告3人次。