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Generalized stability criterion for exploiting optimized mechanical properties by a general correlation between phase transformations and plastic deformations
Acta Materialia ( IF 8.3 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.actamat.2020.10.005
Linke Huang , Weitong Lin , Yubing Zhang , Dan Feng , Yujiao Li , Xiang Chen , Kai Niu , Feng Liu

Abstract Designing structured materials with optimized mechanical properties generally focuses on engineering microstructures, which are closely determined by the processing routes, such as phase transformations. However, the direct connection between phase transformations and mechanical properties remains largely unexplored. Here, we propose a new concept of generalized stability (GS) to correlate phase transformations with plastic deformations in terms of the trade-off relationship that exists between thermodynamics and kinetics. We then suggest that, to achieve structured materials with excellent strength–plasticity combinations, phase transformations and/or plastic deformations with high GS, thermodynamic driving force (ΔG), and kinetic activation energy (Q), are highly expected. We verify the GS concept against a phase transformation-modulated nanostructured Fe alloy, for which an ultrahigh yield strength of 2.61 GPa and an ultimate compressive strength of 3.32 GPa while having a total strain to failure of 35% are achieved via multiple strengthening and hardening mechanisms. A theoretical analysis, in combination with microstructural characterization, indicates that the desired thermo-kinetic parameter triplets (i.e., high GS-high ΔG-high Q) could be inherited from the phase transformation to the plastic deformation, which ultimately yields good mechanical performance. The proposed concept can be regarded as the first theoretical criterion or a general rule that correlates phase transformation with plastic deformation, and can assist in the rapid selection of phase transformations to facilitate superior mechanical properties.

中文翻译:

通过相变和塑性变形之间的一般相关性来开发优化机械性能的广义稳定性准则

摘要 设计具有优化机械性能的结构材料通常侧重于工程微观结构,这与相变等加工路线密切相关。然而,相变与机械性能之间的直接联系在很大程度上仍未得到探索。在这里,我们提出了广义稳定性 (GS) 的新概念,以根据热力学和动力学之间存在的权衡关系将相变与塑性变形相关联。然后我们建议,为了获得具有优异强度-塑性组合的结构化材料,高度期望具有高 GS、热力学驱动力 (ΔG) 和动能活化能 (Q) 的相变和/或塑性变形。我们针对相变调制的纳米结构 Fe 合金验证了 GS 概念,通过多种强化和硬化机制实现了 2.61 GPa 的超高屈服强度和 3.32 GPa 的极限压缩强度,同时具有 35% 的总失效应变. 理论分析与微观结构表征相结合,表明所需的热动力学参数三元组(即高 GS-高 ΔG-高 Q)可以从相变到塑性变形继承,最终产生良好的机械性能。所提出的概念可以被视为第一个理论标准或将相变与塑性变形相关联的一般规则,
更新日期:2020-12-01
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