The influence of vacancies diffusion-induced dislocation climb on the creep and plasticity behaviors of nickel-based single crystal superalloy
The influence of vacancies diffusion-induced dislocation climb on the creep and plasticity behaviors of nickel-based single crystal superalloy
复制标题
空位扩散诱导位错攀爬对镍基单晶高温合金蠕变和塑性行为的影响
DOI：
10.1016/j.commatsci.2014.12.035
复制
发表时间：
2015
影响因子：
3.3
通讯作者：
Li Zhenhuan
中科院分区：
文献类型：
--
作者：
Yang Hui;Huang Minsheng;Li Zhenhuan
在通常高温工作的镍基单晶高温合金中，除位错滑移外，空位扩散引起的位错攀移是一种重要的蠕变/塑性机制。为了揭示和捕捉NBSCS一次蠕变和早期塑性背后的位错动力学机制，扩展了纯滑动三维离散位错动力学(3D-DDD)模拟框架，引入了空位扩散诱导的攀移机制。利用这一扩展的3D-DDD框架，模拟了NBSCS中γ基窄通道中的攀移辅助位错滑移，研究了高温服役的NBSCS的初期蠕变和早期塑性行为，特别是位错攀移在其中的重要作用。详细研究了环境温度、外加应力和空位过饱和度等直接影响位错攀移速度的重要因素，以及两相组织的尺寸(即析出相尺寸和基质通道宽度)对NBSCSS一次蠕变的影响。此外，还详细研究和讨论了位错攀移在NBSCSS早期塑性行为中的重要作用，包括应变速率效应和拉-压不对称性。此外，还再现了位错攀移引起的典型位错组态及其动力学演化，包括包裹在析出物拐角的三角形位错环和{0，0，1}γ/γ‘界面上的位错结，与实验观察和前人发表的计算模拟结果一致。
In the nickel-based single crystal superalloys (NBSCSs) that usually works at high temperature, the vacancies diffusion-induced dislocation climb is an important creep/plasticity mechanism besides the dislocation glide. In order to uncover and capture the dislocation dynamics mechanisms behind primary creep and early plasticity of NBSCSs, the glide-only three-dimensional discrete dislocation dynamics (3D-DDD) simulation framework is extended by incorporating the vacancies diffusion-induced climb mechanism. By means of this extended 3D-DDD framework, the climb-assisted dislocation glide in the narrow γ matrix channels of NBSCSs is simulated to study the primary creep and early plasticity behaviors of NBSCSs serving at elevated temperature, with special attention on the important role of dislocation climb in them. The influences of some important factors, such as ambient temperature, applied stress and vacancy supersaturation, which can directly affect the dislocation climb velocity, and the sizes of the two-phase microstructure (i.e., the precipitate size and matrix channel width) on the primary creep of NBSCSs, are studied in detail. In addition, the important role that dislocation climb plays in the early plasticity behaviors of NBSCSs, including the strain rate effect and the tension–compression (T–C) asymmetry, is investigated and discussed carefully. Moreover, some dislocation climb-induced typical dislocation configurations and their dynamics evolutions, including the triangular dislocation loop wrapping around the corner of the precipitate and the dislocation junctions on the {0 0 1} γ/γ′ interface, are reproduced, in good agreement with the experimental observation and previous computational simulation published.