摘要
国际热核聚变实验堆(ITER)中的偏滤器部分受到大量氦、氢离子流轰击,钨因熔点高、高温性能优异而常被选作这一部件的护甲材料,但氦、氢倾向于在晶界等缺陷处聚集成团簇,从而引起钨表面起泡、肿胀等,致使材料性能下降,使用寿命下降。文中采用分子静力学方法研究了氦和氢在钨晶界附近的性质。首先计算了25个绕<100>轴旋转不同角度的对称倾斜钨晶界的晶界能,选取其中能量较低的∑5(310)和∑5(210)晶界为研究对象,计算了缺陷与晶界的相互作用。结果表明:在晶界附近,垂直于界面的方向上原子层间距明显增大,晶界的膨胀畸变和面间滑移为缺陷提供了有利环境;晶界的影响区域为4,在这一范围内空位、间隙氦和间隙氢的形成能小于块体中的;当离晶界面距离大于4,可近似认为是块体。研究结果可为钨中氦/氢泡生长和释放相关的实验提供一定依据和指导。
The divertor plates in the International Thermonuclear Experimental Reactor（ ITER） are subjected to high-flux helium, hydrogen plasma bombardment. Due to the high temperature capabilities and good sputtering erosion resistance of tungsten,it has been chosen as the most promising candidate armor material for these components. Helium and hydrogen atoms have a strong tendency to accumulate in defects such as grain boundaries（ GB）. The accumulation of impurities results in the formation of bubbles,which are responsible for detrimental effects of materials such as blistering and swelling, ultimately resulting in the deterioration of mechanical properties of materials. In this paper,molecular statics simulation was employed to investigate the behavior of helium and hydrogen near GB of tungsten. Firstly,the GB energies of twenty-five types of symmetric100 tilt GBs with different misorientation angles were calculated. Then the ∑ 5（ 310） and ∑ 5（ 210） GBs,which have lower interfacial energies,were chosen to study the interaction between defects and GBs in tungsten. The results show that in the direction perpendicular to the GB plane,the atomic layer spacing near GB is larger than that of bulk. The expansion in GB and displacement between GB surfaces provide a good environment for defect formation and trapping. The influence range of GB is about 4 ,where the formation energies of vacancies,interstitial helium and hydrogen atoms are smaller than that of bulk. The regions that the distance from GB is larger than 4 can be considered as bulk-like regions. These results can provide some reference for the experiment.
出处
《广西大学学报（自然科学版）》
CAS
北大核心
2017年第6期2113-2119,共7页
Journal of Guangxi University（Natural Science Edition）
基金
国家自然科学基金资助项目(11405034)
广西自然科学基金资助项目(2015GXNSFBA139011)
2016年广西大学"大学生创新创业训练计划"(201610593223)
关键词
氦
氢
钨晶界
分子静力学模拟
helium
hydrogen
tungsten grain boundary
molecular statics simulation
