当前位置: X-MOL 学术Eur. J. Mech. A Solids › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Dislocation nucleation and segregation under adhesive contact of a nano-asperity coating on a crystalline solid
European Journal of Mechanics - A/Solids ( IF 4.1 ) Pub Date : 2021-05-04 , DOI: 10.1016/j.euromechsol.2021.104311
Seung Tae Choi , Nghia Trong Mai , Vinh Phu Nguyen

Crystalline metals are typically coated with materials such as natural oxides for engineering applications, wherein the coating surface has nanoscale roughness. Although the nanoscale asperities of material surfaces typically play a key role in the evolution of surface plasticity under contact loading, the dislocation activities interplaying with a nano-asperity coating and the resulting non-trivial surface microplasticity are yet to be investigated. In this study, the nanoscale roughness of a coating layer is modeled with a stepped coating to investigate its effect on the dislocation nucleation and surface microplasticity evolution. The adhesive contact of a flat indenter on a stepped coating on a substrate was analyzed as a unit process of dislocation emission from the surface step using continuum anisotropic elasticity, which further provided the critical applied stresses required for an incipient dislocation to be emitted from the interface as well as the configurational forces acting on the dislocation. In addition, molecular dynamics simulation of a stepped coating on a crystalline face-centered cubic metal was conducted using the large-scale atomic/molecular massively parallel simulator. The interatomic potential of the coating material and the atomic interaction between the flat indenter and coating were modeled using the Lennard-Jones potential, whose parameters were adjusted to tailor the elastic constants, residual stress in the coating layer, and adhesion energy between the flat indenter and coating. When the indenter was compressed against the coating with a surface step, dislocations were nucleated from the step and emitted into the metal substrate, from which the effects of protective coating on the dislocation nucleation and evolution of surface microplasticity were investigated. Furthermore, the formation of a dislocation double layer due to dislocation segregation was re-examined in the presence of a coating layer. The results of this study have potential implications for nanoscale thin film engineering, and the unit process model can serve as a building block for developing a scale-bridging and statistical model of rough surface contact.



中文翻译:

在晶体固体上的纳米粗糙涂层的粘合剂接触下位错成核和偏析

结晶金属通常用诸如天然氧化物之类的材料涂覆以用于工程应用,其中,涂覆表面具有纳米级的粗糙度。尽管材料表面的纳米级凹凸通常在接触载荷下表面可塑性的演变中起关键作用,但位错活性与纳米级粗糙涂层相互作用以及由此产生的非平凡表面微塑性仍待研究。在这项研究中,用阶梯涂层对涂层的纳米级粗糙度进行建模,以研究其对位错形核和表面微塑性演变的影响。所述粘合剂接触使用连续各向异性各向异性分析了基底上台阶涂层上平压头的位移,作为表面台阶上位错发射的单位过程,这进一步提供了从界面发射初期位错所需的临界外加应力,以及作用于位错的构型力。此外,使用大规模原子/分子大规模并行模拟器对结晶面心立方金属上的阶梯涂层进行了分子动力学模拟。所述原子间作用势使用的Lennard-Jones势,其参数被调整以调节涂层材料和平面压头和涂层之间的原子相互作用进行建模弹性常数,涂层中的残余应力以及平坦压头和涂层之间的附着力。当用表面台阶将压头压在涂层上时,位错从台阶上成核并释放到金属基材中,由此研究了保护层对位错成核和表面微塑性演变的影响。此外,在存在涂层的情况下,重新检查了由于位错偏析而形成的位错双层。这项研究的结果对纳米级薄膜工程具有潜在的影响,单位工艺模型可以作为开发粗糙表面接触的尺度桥接和统计模型的基础。

更新日期:2021-05-08
down
wechat
bug