金属玻璃中滑移的精确可解模型
Exactly solvable model of sliding in metallic glass
摘要：
在低温下，T -> 0，完美晶体的屈服应力等于其所谓的理论强度。非完整晶体的屈服应力由位错迁移率的应力阈值控制。非晶态固体既没有理想的结构，也没有滑移位错。其屈服应力，即宏观非弹性变形开始时的应力，取决于局部非弹性变形发生时的局部（归因于每个原子位置）临界应力的分布。本文描述了具有任意均匀局部临界应力分布的平面层强度和滑移的精确可解模型。找到了非热滑动的宏观应力门槛值，描述了滑动层的热激活蠕变动力学。热激活滑动的速率与低温强度参数密切相关。滑动激活体积与所施加的外部应力成比例，其中β<1。所提出的模型解释了多簇金属玻璃低温变形的机制和屈服应力，因为多簇金属玻璃的簇间边界是所述类型的自然滑动层。
英文摘要：
At low temperature, T -> 0, the yield stress of a perfect crystal is equal to its so called theoretical strength. The yield stress of non-perfect crystals is controlled by the stress threshold of dislocation mobility. A non-crystalline solid has neither an ideal structure nor gliding dislocations. Its yield stress, i.e. the stress at which the macroscopic inelastic deformation starts, depends on distribution of local, attributed to each atomic site, critical stresses at which the local inelastic deformation occurs. We describe exactly solvable model of planar layer strength and sliding with an arbitrary homogeneous distribution of local critical stresses. The macroscopic stress threshold of the athermal sliding is found. Kinetics of thermally-activated creep of the sliding layer is described. The rate of the thermally activated sliding is tightly connected with parameters of the low temperature strength. The sliding activation volume scales with the applied external stress as ~ σ^-β, where β<1. The proposed model accounts for mechanisms and the yield stress of the low temperature deformation of polycluster metallic glasses, since intercluster boundaries of a polycluster metallic glass are natural sliding layers of the described type.
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