IMECH-IR  > 非线性力学国家重点实验室
Alternative TitleBoson Peak Interpretation of Plastic Flow in Metallic Glasses
Thesis Advisor蒋敏强
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline固体力学
Keyword非晶合金 塑性流动 剪切转变 玻色峰 方向序
Other Abstract






    Not like the dislocation-mediated plasticity of crystals, there is much controversy on the plastic flow of amorphous alloys with long-range disorder, since its structural origin is not clear. Amorphous alloys as a new member of glasses display an excess of low-frequency vibrational density of states over the Debye level, i.e., the so-called "boson peak". From a viewpoint of atomic vibrations, the boson peak opens an window into the structural origin of amorphous plasticity. To this end, this study performs both atomistic simulations and theoretical analyses, and some results are obtained as follows.

1. Through analyzing the atomic vibrations in different local environments, an structural parameter, termed orientation order, is proposed to characterize the most probable direction of low-frequency modes contributing to the boson peak. It is interesting to find that the intensity of boson peak has a linear dependence with the length of orientation order. Spatially, the orientation order shows an inhomogeneous distribution, which is consistent with the picture of the quasi-localized modes.

2. The motion equations of atoms in amorphous alloys are decoupled via diagonalizing Hessian Matrix. It is revealed that the large displacements of atoms in amorphous alloys are controlled by those low-frequency modes belonging to boson peak. Based on this, the stress relaxation around Tg, a typical plastic behavior, can be quantitatively described.

3. The shear transformation events is captured in time domain, by using the sudden increasing of boson peak as an indicator. The spatial location of shear transformation is predicted by atomic participation ratio within the boson peak frequencies.

Call NumberMas2018-029
Document Type学位论文
Recommended Citation
GB/T 7714
杨杰. 非晶合金塑性流动的玻色峰解释[D]. 北京. 中国科学院大学,2018.
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