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本文基于密度泛函理论第一原理方法,从影响力学性能本质的电子结构计算上,对含∑5{001}扭转晶界位错Al金属拉伸强度进行了预测,发现其理论拉伸强度达到8.73 GPa,临界应变为24%.拉伸强度低于文献报道(Phys.Rev.B 75,174101(2007))的倾斜晶界位错Al金属的理论拉伸强度9.5 GPa,但其临界应变却远大于倾斜晶界的16%.本研究结果表明,通过工艺参数控制,改变缺陷形态,可极大地改变其力学性能.进一步地,从电子结构层次上,分析了含晶界位错Al金属拉伸断裂行为的实质,通过分析电荷密度分布、键长变化等,发现其断裂处发生在晶界处;理论计算结果将对Al金属结构设计及力学性能改善具有重要的指导作用.
Based on the first principles of density functional theory, from the calculation of the electronic structure that affects the nature of mechanical properties, the tensile strength of dislocated Al metal with Σ5 {001} grain boundaries is predicted and the theoretical tensile strength 8.73 GPa and a critical strain of 24%. The tensile strength is lower than the theoretical tensile strength of 9.5 GPa in slanted grain boundary dislocations reported in the literature (Phys. Rev. B 75, 174101 (2007)), but the critical strain Which is much larger than 16% of the inclined grain boundaries.The results of this study show that the mechanical properties can be greatly changed by controlling the process parameters and changing the defect morphology.Furthermore, from the electronic structure level, The essence of tensile fracture behavior is analyzed by analyzing charge density distribution and bond length variation. It is found that the fracture occurs at the grain boundary. The theoretical calculation results will play an important guiding role in the design of Al metal structure and the improvement of mechanical properties.