ABSTRACT

The mechanism of crystallographic orientation dependent on helium-induced blister formation in plasma-facing tungsten was studied by helium implantation, scanning electron microscopy (SEM) observation, and molecular dynamics (MD) simulation. In the present work, the electropolished high-purity tungsten was exposed to 18 keV helium ions to a fluence of 1.1 × 10¹⁸ He·cm^-2at room temperature. Combined with the electron backscatter diffraction (EBSD) techniques, scanning electron microscopy observations indicate that crystallographic orientation of the underlying grain controls the behavior of blister formation. It is obvious that different grains developed different morphologies after helium implantation, and the severe blisters with larger size and higher exfoliation ratio were observed on grains oriented near <100> direction. Based on the strain–stress relation obtained from MD simulation, it was found that the blisters on grains with orientation near <100> direction grows quickly and exfoliate firstly, and the severe blistering will be achieved for grains oriented near <111> direction. It could also be foreseen that much higher fluence was expected to introduce more severe blisters on grains near <111> direction.

摘要

通过氦注入、扫描电子显微镜 (SEM) 观察和分子动力学 (MD) 模拟研究了晶体取向依赖于面向等离子体的钨中氦诱导气泡形成的机制。在目前的工作中，电解抛光的高纯钨暴露于 18 keV 氦离子，通量为 1.1 × 10 ¹⁸ He·cm ^-2在室温下。结合电子背散射衍射 (EBSD) 技术，扫描电子显微镜观察表明底层晶粒的晶体取向控制着气泡形成的行为。很明显，不同晶粒在注入氦气后形成了不同的形貌，并且在接近<100>方向的晶粒上观察到了更大尺寸和更高剥落率的严重气泡。根据MD模拟得到的应变-应力关系发现，取向接近<100>方向的晶粒上的气泡迅速生长并首先剥落，而取向接近<111>方向的晶粒将出现严重的气泡。