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本文采用分子动力学模拟方法研究了在拉伸载荷下,堆垛层错和温度对纳米多晶镁力学性能的影响.在模拟中,采用嵌入原子势描述镁原子之间的相互作用.计算结果表明:在纳米晶粒中引入堆垛层错能明显增强纳米多晶镁的屈服应力,但堆垛层错对纳米多晶镁杨氏模量的影响很小;温度为300.0K时,孪晶在晶粒交界附近形成,孪晶随着拉伸应变的增加而逐渐生长.当拉伸应变达到0.087时,一种基面与X-Y面成大约35°角且内部包含堆垛层错的新晶粒成核并快速增长.也就是说,孪晶和新晶粒的形成和繁殖是含堆垛层错的纳米多晶镁在300.0K温度下的主要变形机理.模拟结果也显示,当温度为10.0K时,位错的成核和滑移是含堆垛层错的纳米多晶镁拉伸变形的主要形式.
In this paper, the influence of stacking faults and temperature on the mechanical properties of nano-polycrystalline magnesium under tensile load was studied by using molecular dynamics simulation method.In the simulation, the interaction between magnesium atoms was described by using embedded atomic potential The results show that the introduction of stacking faults in nanocrystalline grains can significantly increase the yield stress of nanosized polycrystalline magnesium. However, the stacking faults have little effect on the Young’s modulus of nanocrystalline polycrystalline magnesium. When the temperature is 300.0K, Formed near the grain boundaries and twins grew as the tensile strain increased.When the tensile strain reached 0.087, a new crystal with a base surface at an angle of about 35 ° to the XY plane and containing internal stacking faults The nucleation and rapid growth of the grains, that is to say, the formation and propagation of twins and new grains are the main deformation mechanisms of the nanosized polycrystalline magnesium with stacking faults at 300.0 K. The simulation results also show that when the temperature is At 10.0K, nucleation and slip of dislocations are the main forms of tensile deformation of nanometer polycrystalline magnesium with stacking faults.