论文标题
脆弱模型二进制玻璃中的微塑性
Micro-plasticity in a fragile model binary glass
论文作者
论文摘要
对型号的二进制玻璃，应应变速率低至$ 10^{4} $/sec（对应于每1 $ $ $ $ sec的0.01剪切应变），对名义上弹性状态的原子变形模拟进行了。尽管在考虑的四个数量级应变速率上发生了完全不同程度的结构弛豫，但显示出较小的弹性软化，显示出强大的弹性。对原子尺度结构的仔细检查表明，对于两种局部原子环境，材料响应明显不同。跨越Iscosahedrally协调子结构的系统纯粹是弹性响应的，而其余的子结构也接受了微塑料的进化。这导致了异质的内部应力分布，卸载后会导致负蠕变并完全残留应变恢复。关于局部应力，原子位移和SU（2）局部粘结拓扑的详细结构分析表明，这种微观过程可能会导致局部应力发生很大变化，并且在几何沮丧的区域中更可能发生，其特征是以更高的自由体积和较高的弹性刚度为特征。这些见解将原子光放到结构起源上，该结构起源可能控制着响应弹性载荷方案的最新实验观察结果。
Atomistic deformation simulations in the nominally elastic regime are performed for a model binary glass with strain rates as low as $10^{4}$/sec (corresponding to 0.01 shear strain per 1$μ$sec). A robust elasticity is revealed that exhibits only minor elastic softening, despite quite different degrees of structural relaxation occurring over the four orders of magnitude strain rates considered. A closer inspection of the atomic-scale structure indicates the material response is distinctly different for two types of local atomic environments. A system spanning iscosahedrally coordinated substructure responds purely elastically, whereas the remaining substructure also admits microplastic evolution. This leads to a heterogeneous internal stress distribution which, upon unloading, results in negative creep and complete residual-strain recovery. A detailed structural analysis in terms of local stress, atomic displacement, and SU(2) local bonding topology shows such microscopic processes can result in large changes in local stress and are more likely to occur in geometrically frustrated regions characterized by higher free volume and softer elastic stiffness. These insights shed atomistic light onto the structural origins that may govern recent experimental observations of significant structural evolution in response to elastic loading protocols.
