剪切应力下扩展位错穿越孔洞和夹杂相的相场模拟  

Phase field simulation of an extended dislocation passing through void and inclusion under shear stress

作　　者：郭文慧 倪勇[1] GUO Wenhui;NI Yong(Department of Modern Mechanics, School of Engineering Science, University of Science and Technology of China, Hefei 230027, China)

机构地区：[1]中国科学技术大学工程科学学院近代力学系,安徽合肥230027

出　　处：《中国科学技术大学学报》2020年第4期542-550,共9页JUSTC

基　　金：国家自然科学基金(11672285)资助.

摘　　要：利用结合了相场微弹性理论和位错派纳模型的相场方法,数值模拟研究了面心立方晶体铝和铜中剪切应力下扩展位错穿越孔洞和夹杂相的过程.相场微弹性理论用来计算位错和孔洞/夹杂相之间的长程弹性相互作用,派纳模型中采用一维晶体能函数描述扩展位错结构,Ginzburg-Landau动力学方程描述位错滑移的过程.模拟结果显示位错接近孔洞时,位错先被吸引到孔洞边缘而后被钉扎最后脱离孔洞;而当位错接近夹杂相时,位错先被夹杂相弯曲而后绕过夹杂相并产生位错环.研究发现层错能比较小的情况下扩展位错接近孔洞/夹杂相时会发生层错收窄,而绕过孔洞/夹杂相时会出现领先不全位错先穿越、滞后不全位错后穿越并伴随局部层错展宽的现象.该模拟结果不仅与前人原子层次模拟结果一致,而且进一步在更长的时间尺度下揭示了应力幅值、层错能参数对扩展位错穿越孔洞/夹杂相动力学过程的影响.The dynamics of the extended dislocation passing through the void and inclusion in the face-centered cubic(FCC)crystals of aluminum(Al)and copper(Cu)under shear stress were simulated by phase-field method combined with the phase-field microelasticity(PFM)theory and the Peierls-Nabarro(PN)model,respectively.The PFM theory was employed to calculate the long-range elastic interaction between the dislocation and the void(or the inclusion phase),the PN model was used to describe the structure of the extended dislocation based on the one-dimensional crystal energy function,and the Ginzburg-Landau dynamic equation was used to describe the movement of the dislocation.The simulated results showed that when the dislocation slips to the void,the dislocation is attracted to the edge of the void first and then pinned and finally depinned.When the dislocation slips to the inclusion phase,the dislocation is first bent by the inclusion and then passes through the inclusion with a dislocation loop left.Moreover,in the case that the stacking fault(SF)energy is relatively low,it was found that the SF narrows when the extended dislocation approaches the void(or the inclusion phase).While an extended dislocation passes through the void(or the inclusion phase),the leading partial dislocation passes through the void first,and then the trailing partial dislocation passes through the void,which is also accompanied by the phenomenon of SF broadening.Our simulation results are not only consistent with the previous atomic simulated results,but also further reveal the effects of stress amplitude and SF energy parameters on the dynamics of the extended dislocation passing through the void(or the inclusion)at a longer time scale.

关 键 词：弹性作用 刃型扩展位错 孔洞 夹杂相 相场模型 

分 类 号：O343.7[理学—固体力学] O772[理学—力学]