基于跨尺度理论计算的γ’析出相强化FCC高熵合金的机理分析

High-entropy alloys are a new type of metal materials that have developed rapidly in recent years. Differing from traditional metal materials, the chemical disorder of high-entropy alloys provides a new idea for the strengthening and toughening of metal structural materials. Recently, the discovery of γ' nanocrystal coherent precipitates in FCC high-entropy alloys provides a new way to solve the strength-ductility trade-off of traditional metal materials. Due to the relatively short history of the development of high-entropy alloys, the research on high-entropy alloys at home and abroad mainly explores its properties through experiments. Recent experimental reports show that precipitation strengthening is an effective means of strengthening high-entropy alloys. Considering the limitation of experiments and the advantage of numerical calculation, this proposal will systematically study the scientific issues of γ' nanocrystalline precipitates in FCC high-entropy alloys by first-principles calculations, phase-field simulation, and finite element calculations. Based on the reported experimental research, the formation conditions and thermal stability of γ' nano-precipitates in FCC high-entropy alloys will be explored; the microstructure evolution of γ' nano-precipitates under mechanical loading will be studied, and the microstructure-macro performance correlation will be established; establish the guiding principles for developing high-performance high-entropy alloys, and develop high-performance high-entropy alloys with engineering application prospects in combination with experiments.

高熵合金是近年来快速发展起来的一类新型金属材料，同传统金属材料由化学成分有序主导不同，高熵合金是一种多主元、本征的化学长程无序金属材料。最近FCC高熵合金中γ’纳米晶共格析出相的发现为解决金属材料强度-韧性的矛盾提供了新的途径。由于高熵合金发展的历史相对较短，目前国内外对于高熵合金的研究主要通过实验探索其性质，实验报道显示析出强化是高熵合金的一种有效强化手段，但是存在着一系列挑战。为了加速高性能高熵合金的研发速度并考虑到理论计算的优越性，本项目将通过基于第一性原理计算、相场模拟和有限元计算的跨尺度理论计算来系统地研究FCC高熵合金中γ’纳米晶析出相的相关科学问题。探索FCC高熵合金中γ’纳米析出相的形成规律和热稳定性；研究高熵合金γ’纳米晶析出相在加载下的微结构动态演化，并建立微结构-宏观性能的关联；建立开发高性能高熵合金的指导原则，并同实验结合开发出具有工程应用前景的高性能高熵合金。

高熵合金是一种基于崭新材料设计理念的新型金属材料，由于其优异的力学性能，高熵合金已经吸引了材料科学家们极大的研究兴趣并显示出重要的应用前景。析出强化是显著提升FCC高熵合金力学性能的重要途径之一，然而高熵合金的发展历史相对较短，FCC高熵合金力学性能的提升建立在对析出相的形核/长大、晶粒粗化、相稳定性等相关科学问题的深入理解之上。本项目以FCC高熵合金为研究对象，通过第一性原理计算、分子动力学模拟、蒙特卡洛计算、相场模拟、有限元计算及热/动力学计算等多种研究技术，构建了数据驱动的跨尺度关联，开展了FCC高熵合金微观组织演化和宏观力学性能相关的研究。主要取得了以下成果：（1）揭示了典型FCC高熵合金中r’析出相稳定存在的温度和成分区间，针对在加载条件下的微结构动态演化，开发了一套考虑析出相和基体错配应变的纳米晶多组元合金相场模型；（2）提出了通过元素掺杂和退火工艺调控典型FCC高熵合金稳定性的策略；（3）阐明了典型FCC高熵合金强韧化机理及力学性能提升途径；（4）通过跨尺度计算结合机器学习技术实现了典型FCC高熵合金的抗氢脆设计。本项目成功构建了针对高熵合金的跨尺度计算方法，实现了从纳观到宏观更好地理解并提升高熵合金力学性能的目标，最终，本项目的研究成果也成功推广到了其它多组元金属材料领域。