高韧性三元层状陶瓷:从MAX相到MAB相

High-fracture-toughness ternary layered ceramics:from the MAX to MAB phases

三元层状化合物MAX相和新近引起人们注意的MAB相以其兼具陶瓷和金属的共同特性成为结构陶瓷领域20余年的研究热点,而高损伤容限和高断裂韧度是其区别于传统陶瓷的本质特征。本文简要回顾了MAX相的整体发展脉络和MAB相的最新研究进展,重点分析了纳米层状结构对宏观力学行为的影响及其内在机制。基于第一性原理计算结果建立的键刚度模型在实现对化学键强度的定量表征基础上,更重要的是阐明了"足够"弱的层间结合是三元层状陶瓷表现出非凡力学性能的根本原因。而Fe_(2)AlB_(2)在室温附近所出现的磁热效应(MCE)则显示了MAB相化合物在功能领域的良好应用前景。经过20余年的持续研究,MAX相化合物的结构和性能逐渐变得清晰,目前针对具体场景的应用研究在世界各地蓬勃开展起来。然而,目前对MAB相化合物的认识还很有限。因此,合成和表征现有已知MAB相化合物的结构、力学性能、物理性能以及基于应用背景的使役行为是现阶段的重要任务。其中,基于密度泛函理论(DFT)的第一性原理数值模拟可扮演重要角色,正如其在理解MAX相化合物的非凡性能和发现新型化合物时所起的重要作用一样。

The MAX phase of the ternary layered compound and the recently attracted attention of the MAB phase have become the research hotspots in the field of structural ceramics for more than 20 years because of their common characteristics of ceramics and metals.The high damage tolerance and high fracture toughness are different from the essential characteristics of traditional ceramics.The overall development of MAX phase and the latest research progress of MAB phase were briefly reviewed in this article,focusing on the analysis of the effect of multi-scale layered structure on macro-mechanical behavior and its internal mechanism.Based on the results of first-principles calculations,the bond stiffness model was established and the quantitative characterization of chemical bond strength was realized,and more importantly,it was clarified that"sufficiently"weak interlayer bonding is the root cause for the extraordinary mechanical properties of ternary layered ceramics.The magnetocaloric effect(MCE)of Fe_(2)AlB_(2) near room temperature shows the good application prospects of MAB phase compounds in the functional field.After more than 20 years of continuous research,the structure and performance of MAX-phase compounds have gradually become clear.At present,application research for specific scenarios is vigorously carried out all over the world.However,the current knowledge of MAB phase compounds is still very limited.Therefore,synthesizing and characterizing the structure,mechanical properties,physical properties,and service behaviour of existing MAB phase compounds are the important tasks at this stage.First-principles numerical simulation based on density functional theory(DFT)can play an important role,just as in understanding the extraordinary properties of MAX phase compounds and discovering new compounds.