Shear shuffling governs plastic flow in nanocrystalline metals: An analysis of thermal activation parameters
Shear shuffling governs plastic flow in nanocrystalline metals: An analysis of thermal activation parameters
复制标题
剪切洗牌控制纳米晶金属中的塑性流动：热活化参数分析
DOI：
10.1103/physrevb.00.004100
复制
发表时间：
2014
影响因子：
3.7
通讯作者：
R. Birringer
中科院分区：
文献类型：
--
作者：
M. Grewer;R. Birringer
根据对晶粒尺寸 $\ensuremath{\le}$10 nm 的纳米晶 PdAu 合金的应变率和温度相关变形研究，剪切激活体积 (6 ${\text{b}}^{3}$)、应变率灵敏度 ($0.03$) 以及亥姆霍兹 (0.9 eV) 和吉布斯激活自由能 ($\ensuremath{\Delta}G=0.2$ eV)提取的。与金属玻璃的值非常相似，表明晶界介导的剪切改组在纳米尺度低端的塑性中占主导地位。更根本的是，我们发现能垒高度表现出普遍的缩放行为$\ensuremath{\Delta}G\ensuremath{\propto}\ensuremath{\Delta}{\ensuremath{\tau}}^{3/2}$，其中$\ensuremath{\Delta}\ensuremath{\tau}$是残余负载，从而产生了Johnson-Samwer ${T}^{2/3}$缩放定律的推广金属玻璃的屈服。
From strain-rate- and temperature-dependent deformation studies on nanocrystalline PdAu alloys with grain sizes $\ensuremath{\le}$10 nm, the shear activation volume (6 ${\text{b}}^{3}$), strain-rate sensitivity ($0.03$), as well as the Helmholtz (0.9 eV) and Gibbs free energy of activation ($\ensuremath{\Delta}G=0.2$ eV) have been extracted. The close similarity to values found for metallic glasses indicates that grain boundary mediated shear shuffling dominates plasticity at the low end of the nanoscale. More fundamentally, we find that the energy barrier height exhibits universal scaling behavior $\ensuremath{\Delta}G\ensuremath{\propto}\ensuremath{\Delta}{\ensuremath{\tau}}^{3/2}$, where $\ensuremath{\Delta}\ensuremath{\tau}$ is a residual load, giving rise to a generalization of the Johnson-Samwer ${T}^{2/3}$ scaling law of yielding in metallic glasses.