|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Bulk Metallic Glasses XV
||Composition Dependence and Structural Signature of Beta-relaxation in La-based Metallic Glasses
||Xiaodong Wang, Jin Zhang, Qing Yu, Qingping Cao, Jianzhong Jiang
|On-Site Speaker (Planned)
The secondary beta-relaxation is an intrinsic feature of glassy materials. However, its structural origin is still not well understood. Here we discover that the beta-relaxation is composition dependent, which becomes more pronounced and almost decoupled with excess free volume in La-Al-Ni metallic glasses(MGs) by annealing. However, it disappears in the annealed La-Al-Cu MGs. Our results demonstrate that the beta-relaxation in both kinds of MGs more depends on the Ni- and Cu-centered atomic packing structures rather than the overall structural relaxation. By combining synchrotron x-ray techniques with ab initio molecular dynamics, we find that the loose packing in tricapped-trigonal-prism-like polyhedra favors the larger local vibrations of center Ni atoms in the La50Al15Ni35 MG, in contrast with the smaller vibrations of Cu atoms in the close-packed polyhedra in the La50Al15Cu35 MG. This work provides a pathway to understand the different structural relaxation behaviors of MGs from their locally atomic packing and vibrations.
||Planned: Supplemental Proceedings volume