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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Σ 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.By the first-principles calculations based on the density functional theory, the tensile strength of Al metal with dislocations of twist grain boundaries (GBs) is predicted from its electronic structure to its essential mechanical properties. The results show that the theoretical tensile strength for Al twist GB is about 8.73GPa and it is less than that for Al glide GB(9.5GPa) (Phys. Rev. B 75, 174101 (2007)). However, its fracture strain for Al twist GB is 24% and 16% more than that for Al glide GB. It suggests that the mechanical properties of the metal can be greatly improved by experimentally modulating its defect or dislocation. Furthermore, the physics of the fracture of Al twist GB is analyzed by the distributions of charge density and the changes of bond length, and it is found that the facture appears in the GB. Our theoretical predictions can play an important role in guiding the improvement of mechanical properties and structural designs for Al metal.
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