ABSTRACT

A molecular dynamics simulation-based study has been performed to examine the deformation behaviour of the predetermined parallel and perpendicular centreline cracks in CNTs embedded nanocrystalline aluminum (CNTs-NC Al) composite specimens under uniaxial loading. The hybrid potential (i.e. EAM, AIREBO, and LJ) method is adopted for carrying out the tensile deformation at three different temperatures (such as 10 K, 300 K, and 653 K). The mechanical properties are evaluated for both cases of parallel and perpendicular cracks of NC Al and CNTs-NC Al specimens. (30,30) CNT-NC Al specimen has shown superior fracture strain and ultimate tensile strength (UTS) at low temperature, whereas, higher fracture strain and lower UTS at high temperature than NC Al specimen. The mechanical properties of CNTs-NC Al nanocomposites are affected by the pre-existing crack and loading direction. The CNTs-NC Al nanocomposite specimens have exhibited the highest dislocation density compared to the NC Al specimen. The Shockley partial dislocations are a major driving factor for the parallel and perpendicular cracks of both (NC Al and CNTs-NC Al) specimens. The structural evolution and defect variation (such as stacking faults interaction with various dislocations, twin boundary, and grain boundary widening) has been elucidated during the tensile deformation of NC Al and CNT-NC Al nanocomposites.

摘要

已经进行了基于分子动力学模拟的研究，以检查在单轴加载下 CNTs 嵌入纳米晶铝 (CNTs-NC Al) 复合样品中预定平行和垂直中心线裂纹的变形行为。采用混合势（即EAM、AIREBO和LJ）方法在三种不同温度（如10 K、300 K和653 K）下进行拉伸变形。对 NC Al 和 CNTs-NC Al 试样的平行和垂直裂纹两种情况评估机械性能。(30,30) CNT-NC Al 试样在低温下表现出优异的断裂应变和极限拉伸强度 (UTS)，而高温下的断裂应变和 UTS 低于 NC Al 试样。CNTs-NC Al纳米复合材料的力学性能受预先存在的裂纹和加载方向的影响。与 NC Al 试样相比，CNTs-NC Al 纳米复合材料试样表现出最高的位错密度。肖克利部分位错是（NC Al 和 CNTs-NC Al）试样平行和垂直裂纹的主要驱动因素。在 NC Al 和 CNT-NC Al 纳米复合材料的拉伸变形过程中，已经阐明了结构演变和缺陷变化（例如堆垛层错与各种位错的相互作用、孪晶界和晶界加宽）。肖克利部分位错是（NC Al 和 CNTs-NC Al）试样平行和垂直裂纹的主要驱动因素。在 NC Al 和 CNT-NC Al 纳米复合材料的拉伸变形过程中，已经阐明了结构演变和缺陷变化（例如堆垛层错与各种位错的相互作用、孪晶界和晶界加宽）。肖克利部分位错是（NC Al 和 CNTs-NC Al）试样平行和垂直裂纹的主要驱动因素。在 NC Al 和 CNT-NC Al 纳米复合材料的拉伸变形过程中，已经阐明了结构演变和缺陷变化（例如堆垛层错与各种位错的相互作用、孪晶界和晶界加宽）。