Mapping the kinetic evolution of metastable grain boundaries under non-equilibrium processing
Mapping the kinetic evolution of metastable grain boundaries under non-equilibrium processing
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DOI：
10.1016/j.actamat.2020.09.013
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发表时间：
2020-11
期刊：
影响因子：
9.4
通讯作者：
Zhitong Bai;G. Balbus;D. Gianola;Yue Fan
中科院分区：
文献类型：
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作者：
Zhitong Bai;G. Balbus;D. Gianola;Yue Fan
通过原子建模研究了快速驱动条件下多个亚稳态晶界（GB）的动力学演化。在增强的统计分析的帮助下，绘制出了GB在广泛的亚稳态温度空间上的能量演化，其中以高保真度检索了两种不同的状态——老化状态和恢复状态。通过比较各种条件下（例如随机扰动、等温退火和快速加热/冷却）的结果，表明这种老化/再生机制图是通用的，与用于引发亚稳态GB的实际刺激无关。老化/恢复现象被证明源于系统势能景观连续转变期间上坡攀登和下坡下降的能量不平衡。无需引入自由参数，该模型就可以协调飞秒激光照射下实验测量的纳米晶金属的硬度变化，因此它为实现多种界面状态和促进以前无法达到的性能状态提供了新的视角。
The kinetic evolution of a multiplicity of metastable grain boundaries (GBs) under fast driving conditions are studied by atomistic modeling. Assisted with an enhanced statistical analysis, the energetic evolution of GBs over a broad metastability-temperature space is mapped out, wherein two distinct regimes—an ageing regime and a rejuvenating regime—are retrieved with high fidelity. By comparing the results under various conditions (e.g.random perturbations, isothermal annealing, and fast heating/cooling), it is shown that such ageing/rejuvenating mechanism map is universal, irrespective of the actual stimuli used to elicit the metastable GBs. The ageing/rejuvenating phenomena are demonstrated to stem from the energy imbalance of uphill climbing and downhill dropping during sequential transitions in the system's potential energy landscape. Without the necessity of introducing free parameters, such model can reconcile experimentally measured hardness variation of nanocrystalline metals subjected to femto-second laser irradiation, and it therefore provides a novel perspective on achieving a plurality of interfacial states and facilitating previously inaccessible property regimes.