Microstructure evolution during near- Tg annealing and its effect on shear banding in model alloys

Abstract

By performing extensive molecular dynamics simulations, we investigate the deformation behavior in Al90Sm10 and Cu64.5Zr35.5 alloys after elongated isothermal annealing in the vicinity of the glasstransition temperature (Tg). Different microstructural response to the annealing process was observed: Al90Sm10 maintains the glassy structure with improved energetic stability, enhanced short-range order (SRO), and a more pronounced spatial network that extends beyond the first atomic shell, while Cu64.5Zr35.5 forms nanocrystalline Laves Cu2Zr phases. Shear banding occurs in both annealed systems under shear loading. For Al90Sm10, the spatial network formed by the local clusters characterizing the SRO of the system is significantly weakened but remains appreciable in the shear band. In contrast, the crystalline ordering in the Cu64.5Zr35.5 is completely destroyed during shear banding. Consequently, while displaying higher yield strength, the annealed Cu64.5Zr35.5 sample appears to be less ductile. By carefully examining the effect of microstructures on the structural ordering in the shear band and the consequent mechanical response, our work contributes to a better understanding of the deformation mechanism of amorphous alloys as compared with that in crystalline materials.

Simulation and analysis of melting behavior of local atomic structure of refractory metals vanadium

“…子的任意变化矢量. 通常可以利用正交矩阵与缩放 因子的共同调节使得RMSD可以保持一个测定的 不变量, 从而获得变换后各点距原点的距离 [51] : 15 K/s 2500 3000 3500 4000 4500 此外, 考虑到熔化过程中的MD模拟 [35] 与实 验 [37,40] 均是在有限温度下进行的, 所以本文通过 计算团簇的原子振动频率 [52] 后, 进一步从熵与吉 布斯自由能的角度来研究各团簇的热力学稳定性 [52]…”