Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, FIN-00076 Aalto, Espoo, Finland.
Department of Physics, P.O. Box 43, FIN-00014 University of Helsinki, Finland.
Phys Rev E. 2016 Jan;93(1):013309. doi: 10.1103/PhysRevE.93.013309. Epub 2016 Jan 21.
The stress-driven motion of dislocations in crystalline solids, and thus the ensuing plastic deformation process, is greatly influenced by the presence or absence of various pointlike defects such as precipitates or solute atoms. These defects act as obstacles for dislocation motion and hence affect the mechanical properties of the material. Here we combine molecular dynamics studies with three-dimensional discrete dislocation dynamics simulations in order to model the interaction between different kinds of precipitates and a 1/2〈111〉{110} edge dislocation in BCC iron. We have implemented immobile spherical precipitates into the ParaDis discrete dislocation dynamics code, with the dislocations interacting with the precipitates via a Gaussian potential, generating a normal force acting on the dislocation segments. The parameters used in the discrete dislocation dynamics simulations for the precipitate potential, the dislocation mobility, shear modulus, and dislocation core energy are obtained from molecular dynamics simulations. We compare the critical stresses needed to unpin the dislocation from the precipitate in molecular dynamics and discrete dislocation dynamics simulations in order to fit the two methods together and discuss the variety of the relevant pinning and depinning mechanisms.
在晶体固体中，位错的应力驱动运动，以及随之而来的塑性变形过程，极大地受到各种点状缺陷（如沉淀物或溶质原子）的存在或不存在的影响。这些缺陷作为位错运动的障碍，从而影响材料的机械性能。在这里，我们结合分子动力学研究和三维离散位错动力学模拟，以模拟不同类型的沉淀物与 BCC 铁中的 1/2〈111〉{110} 刃型位错之间的相互作用。我们已经将不可移动的球形沉淀物实现到 ParaDis 离散位错动力学代码中，位错通过高斯势与沉淀物相互作用，对位错段产生一个法向力。用于离散位错动力学模拟的沉淀物势、位错迁移率、剪切模量和位错核心能量的参数是从分子动力学模拟中获得的。我们比较了从分子动力学和离散位错动力学模拟中解除位错与沉淀物的结合所需的临界应力，以拟合两种方法，并讨论了各种相关的固定和解锁机制。
