Cavitation in Amorphous Solids
Cavitation in Amorphous Solids
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DOI：
10.1103/physrevlett.110.185502
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发表时间：
2013-04-30
影响因子：
8.6
通讯作者：
Falk, Michael L.
中科院分区：
文献类型：
--
作者：
Guan, Pengfei;Lu, Shuo;Falk, Michael L.
对金属玻璃中空化的分子动力学模拟表明，空化速率随等待时间的变化而变化。在短时间尺度上，成核速率和临界空穴尺寸与经典成核理论相称，该理论解释了空化过程中的塑性耗散和空穴表面能对空穴尺寸的依赖关系。除了托尔曼长度之外，所有的参数都可以直接从独立的计算中提取，或者根据物理原理进行估计。在较长的时间尺度上，剪切松弛形式的应变时效会导致空化速率的系统性降低。由于表面能在小腔中被抑制而产生的高空化率为金属玻璃中观察到的准脆性断裂提供了可能的解释。
Molecular dynamics simulations of cavitation in a Zr50Cu50 metallic glass exhibit a waiting time dependent cavitation rate. On short time scales nucleation rates and critical cavity sizes are commensurate with a classical theory of nucleation that accounts for both the plastic dissipation during cavitation and the cavity size dependence of the surface energy. All but one parameter, the Tolman length, can be extracted directly from independent calculations or estimated from physical principles. On longer time scales strain aging in the form of shear relaxations results in a systematic decrease of cavitation rate. The high cavitation rates that arise due to the suppression of the surface energy in small cavities provide a possible explanation for the quasibrittle fracture observed in metallic glasses.