A Hall-Petch-Like Relationship Linking Nanoscale Heterogeneity to Yield Stress of Heterogeneous Metallic Glasses
A Hall-Petch-Like Relationship Linking Nanoscale Heterogeneity to Yield Stress of Heterogeneous Metallic Glasses
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DOI：
10.1016/j.ijplas.2023.103759
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发表时间：
2023-09
影响因子：
9.8
通讯作者：
Yucong Gu;Jonathan Cappola;Jian Wang;Lin Li
中科院分区：
文献类型：
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作者：
Yucong Gu;Jonathan Cappola;Jian Wang;Lin Li
金属玻璃（MG）在小变形时通过剪切转变区（STZ）和在大变形时通过剪切带进行塑性变形。STZ机制与微观结构的不均匀性有关，包括与原子聚集及其空间分布相关的纳米不均匀性。剪切带的出现是由于STZ的聚结。在这项研究中，我们调查的屈服行为的异质MG通过改变空间相关性和标准偏差的局部剪切模量与原子簇在纳米尺度上。使用一个细观剪切转变区（STZ）动力学模型，我们计算屈服强度和观察变形行为与STZ的形成和扩展。我们提出了一个霍尔-佩奇的关系，其中的MG规模的屈服应力与空间相关长度的平方根成反比。我们的研究结果表明，MG的屈服对应于STZ从软区到硬区的渗流。在宏观屈服之前，激活的STZ倾向于在软区域内积累，形成Super-STZ阵列，这类似于在晶界处形成位错堆积。我们使用Eshelby夹杂物模型推导出Super-STZ前部的应力集中，并通过空间相关长度和纳米尺度异质性的标准差，制定了Hall-Petch方程来量化MG的产量。我们的研究结果提供了深入了解的结构-性能关系的MG和具有可调性能的纳米MG的设计具有重要意义。
Metallic glasses (MGs) undergo plastic deformation through shear transformation zones (STZs) at small deformations and shear banding at large deformations. The STZ mechanism is linked to microstructural heterogeneities, including nano-heterogeneities associated with atom clustering and their spatial distribution. Shear banding occurs due to the coalescence of STZs. In this study, we investigate the yielding behavior of heterogeneous MGs by varying the spatial correlation and standard deviation of local shear moduli associated with clustering atoms on the nanoscale. Using a mesoscale shear transformation zone (STZ) dynamics model, we compute the yielding strength and observe deformation behaviors associated with the formation and propagation of STZs. We propose a Hall-Petch-like relationship where the yield stress of the MG scales inversely with the square root of the spatial correlation length. Our results show that the yielding of MGs corresponds to the percolation of STZs from soft to hard regions. Prior to macroscopic yielding, the activated STZs tend to accumulate inside soft regions, forming a Super-STZ array, which is similar to the formation of dislocation pile-up at grain boundaries. We derive the stress concentration in the front of the Super-STZ using the Eshelby inclusion model and formulate a Hall-Petch-like equation to quantify the yield of MGs with the spatial correlation length and standard deviation of the nanoscale heterogeneity. Our results provide insights into the structure-property relationship of MGs and have important implications for the design of nanoscale MGs with tunable properties.