Interfacial plasticity governs strain delocalization in metallic nanoglasses
Interfacial plasticity governs strain delocalization in metallic nanoglasses
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DOI：
10.1557/jmr.2019.101
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发表时间：
2019-07-15
影响因子：
2.7
通讯作者：
Trelewicz, Jason R.
中科院分区：
文献类型：
--
作者：
Cheng, Bin;Trelewicz, Jason R.
纳米玻璃塑性中的本征尺寸效应与界面网络施加的结构长度尺度有关，对这一行为的控制对于设计具有更好机械响应的非晶态合金至关重要。本文采用原子模拟方法研究了纳米玻璃中的应变离域现象，并与非晶态晶体结构的界面特征和长度尺度进行了明确的关联。结果表明，在一定条件下，强度与晶粒度无关，但随界面的过剩自由体积和短程有序度而变化。纳米玻璃退火后的结构均匀化增加了它们的强度，使其接近大块金属玻璃的值；然而，持续的应变分配到界面区域阻止了初级剪切带的形成。因此，纳米玻璃塑性中的本征尺寸效应源于界面区偏向塑性应变的积累，这最终将控制纳米玻璃中的应变离域和均匀流动。
Intrinsic size effects in nanoglass plasticity have been connected to the structural length scales imposed by the interfacial network, and control over this behavior is critical to designing amorphous alloys with improved mechanical response. In this paper, atomistic simulations are employed to probe strain delocalization in nanoglasses with explicit correlation to the interfacial characteristics and length scales of the amorphous grain structure. We show that strength is independent of grain size under certain conditions, but scales with the excess free volume and degree of short-range ordering in the interfaces. Structural homogenization upon annealing of the nanoglasses increases their strength toward the value of the bulk metallic glass; however, continued partitioning of strain to the interfacial regions inhibits the formation of a primary shear band. Intrinsic size effects in nanoglass plasticity thus originate from biased plastic strain accumulation within the interfacial regions, which will ultimately govern strain delocalization and homogenous flow in nanoglasses.