论文标题
塑料屈服和变形爆发在存在来自连贯沉淀的无序的情况下
Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates
论文作者
论文摘要
与其他元素合金的金属通常是为了提高材料强度或硬度。一个关键的显微镜机制是降水硬化，降水阻碍了脱位运动，但是这种障碍在确定集体脱位动力学性质中的作用仍有待理解。在这里，使用来自零沉淀的完全相干球形沉淀的FCC单晶的三维离散脱位动力学模拟，最高为$ρ_p= 10^{21} \，\ \ \ \ \ text {m}^{ - 3} $，并以各种脱位 - 脱位 - 脱位相互作用的互动强度。当脱位前后相互作用不起作用时，屈服在纯晶体上是质量的，即以“脱位堵塞”为主，导致玻璃脱位动力学在任何应力值下表现出关键特征。我们证明，增加沉淀的密度和/或脱位 - 接种相互作用强度会产生真正的产量或脱位组件，并具有临界的屈服应力。这在脱位雪崩的统计数据中可以清楚地看到，当在逐渐增加外部应力时观察到的雪崩量，并且在系统对恒定施加应力的响应中也表现出来。根据培根 - 骨堆古的关系，讨论了与沉淀物的屈服缩放。
Alloying metals with other elements is often done to improve the material strength or hardness. A key microscopic mechanism is precipitation hardening, where precipitates impede dislocation motion, but the role of such obstacles in determining the nature of collective dislocation dynamics remains to be understood. Here, three-dimensional discrete dislocation dynamics simulations of FCC single crystals are performed with fully coherent spherical precipitates from zero precipitate density upto $ρ_p = 10^{21}\,\text{m}^{-3}$ and at various dislocation-precipitate interaction strengths. When the dislocation-precipitate interactions do not play a major role the yielding is qualitatively as for pure crystals, i.e., dominated by "dislocation jamming", resulting in glassy dislocation dynamics exhibiting critical features at any stress value. We demonstrate that increasing the precipitate density and/or the dislocation-precipitate interaction strength creates a true yield or dislocation assembly depinning transition, with a critical yield stress. This is clearly visible in the statistics of dislocation avalanches observed when quasistatically ramping up the external stress, and is also manifested in the response of the system to constant applied stresses. The scaling of the yielding with precipitates is discussed in terms of the Bacon-Kocks-Scattergood relation.
