Grove Maximilian, Peterlechner Martin, Rösner Harald, Imlau Robert, Zaccone Alessio, Wilde Gerhard
Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany.
Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany.
Ultramicroscopy. 2021 Apr;223:113220. doi: 10.1016/j.ultramic.2021.113220. Epub 2021 Feb 9.
Shear bands resulting from plastic deformation in cold-rolled AlYFe metallic glass were observed to display alternating density changes along their propagation direction. Electron-energy loss spectroscopy (EELS) was used to investigate the volume plasmon energy losses in and around shear bands. Energy shifts of the peak centre and changes in the peak width (FWHM) reflecting the damping were precisely determined within an accuracy of a few meV using an open source python module (Hyperspy) to fit the shapes of the plasmon and zero-loss peaks with Lorentzian functions. The maximum bulk plasmon energy shifts were calculated for the bright and dark shear band segments relative to the matrix to be about 38 and 14 meV, respectively. The damping was observed to be larger for the denser regions. The analysis presented here suggests that the changes in the plasmons are caused by two contributions: (i) Variable damping in the shear band segments due to changes in the medium-range order (MRO). This affects the static structure factor S(k), which, in turn, leads to either reduced or increased damping according to the Ziman-Baym formula. (ii) The ionic density and the effective electron mass appearing in the zero-momentum plasmon frequency formula E(q=0) are coupled and give rise to small variations in the plasmon energy. The model predicts plasmon energy shifts in the order of meV.
观察到冷轧AlYFe金属玻璃中塑性变形产生的剪切带沿其传播方向呈现出交替的密度变化。利用电子能量损失谱（EELS）研究了剪切带内部及周围的体等离子体能量损失。使用开源Python模块（Hyperspy），通过用洛伦兹函数拟合等离子体峰和零损失峰的形状，在几meV的精度范围内精确确定了反映阻尼的峰中心能量位移和峰宽（半高宽）变化。相对于基体，计算出明亮和黑暗剪切带段的最大体等离子体能量位移分别约为38和14 meV。观察到较密集区域的阻尼更大。这里提出的分析表明，等离子体的变化由两种因素引起：（i）由于中程有序（MRO）变化，剪切带段中的可变阻尼。这会影响静态结构因子S(k)，进而根据齐曼-贝姆公式导致阻尼减小或增大。（ii）零动量等离子体频率公式E(q = 0)中出现的离子密度和有效电子质量相互耦合，导致等离子体能量出现小的变化。该模型预测等离子体能量位移在meV量级。
