α-铁中氦缺陷对氢原子的俘获

体心立方结构的金属铁(α-铁)是聚变反应堆重要的候选结构材料,受氢和氦原子的辐照后可能会发生力学性能的退化。了解氢和氦原子在铁中的聚集行为是反应堆聚变材料研究的重点。本文采用密度泛函理论计算了α-铁中HeHn集团的稳定性,揭示了替代位氦缺陷俘获氢原子的过程和机制,结果表明,1个氦原子最多可俘获4个氢原子,被俘获的氢原子占据氦原子周围的八面体间隙位,且氢原子倾向于彼此聚拢。对氢原子俘获能的计算表明,氢原子足量时,HeH4是α-铁中主要的氢氦集团构型,反之则以HeH2为主。

Hydrogen Trapping by Helium Defects in α-Fe

The α-Fe is considered as a promising candidate for structure material in fusion reactors, which may undergo mechanical degradation due to irradiation of hydrogen and helium atoms. The clustering behavior of hydrogen and helium atoms in α-Fe is an important concern in fusion materials research. Using density functional theory calculations, the stability of the HeH_n cluster and the trapping behavior of hydrogen atoms by a substitutional helium defect were investigated. And it shows that a helium atom can trap four hydrogen atoms at most, and the trapped hydrogen atoms tend to sit neighboring octahedral sites. The trapping energy of hydrogen atoms implies that HeH₄ is the major structure in α-Fe when hydrogen atoms are abundant, and HeH₂ predominates otherwise.