Collision cascades initiated by fast Ni projectiles with energy E = 5, 10, 15 and 20 keV at the surface of nickel target at temperature T = 100, 300, 600, 900 and 1200 K were studied by molecular dynamics simulations. Representative sampling of 24 surface collision cascades per $\left(E,T\right)$ set was generated to get the statistically reliable number of Frenkel pairs $N_{\mathit{FP}}$ and the fraction of vacancies ${\sigma }_{\mathit{vac}}$ and self-interstitial atoms (SIAs) ${\sigma }_{\mathit{SIA}}$ in point defect clusters as functions of the projectile energy and irradiation temperature. It was established that $〈N_{\mathit{FP}}〉,〈{\sigma }_{\mathit{vac}}〉$ and $〈{\sigma }_{\mathit{SIA}}〉$ in surface collision cascades in nickel averaged over cascade series with the same $\left(E,T\right)$ are higher than those produced in collision cascades in the bulk of the material under the same simulation conditions. Point defects generated in surface cascades predominantly agglomerate into clusters. Spatial separation of vacancies and SIAs due to the interaction of collision cascades with the free surface is the major driving mechanism responsible for the increased number of $〈N_{\mathit{FP}}〉,〈{\sigma }_{\mathit{vac}}〉$ and $〈{\sigma }_{\mathit{SIA}}〉$ produced in surface collision cascades in nickel.

通过分子动力学模拟研究了镍靶表面上能量为E = 5、10、15和20 keV的快速Ni弹丸在温度为T = 100、300、600、900和1200 K时引发的碰撞级联。每个24个表面碰撞级联的代表性采样$\left(Ë，Ť\right)$ 生成集合以获得统计上可靠的Frenkel对数 ${ñ}_{\mathit{FP}}$ 和空缺的分数 ${\sigma }_{\mathit{真空}}$ 和自填隙原子（SIA） ${\sigma }_{\mathit{新航}}$点缺陷簇的位置取决于射弹能量和照射温度。已经确定$〈{ñ}_{\mathit{FP}}〉，〈{\sigma }_{\mathit{真空}}〉$ 和 $〈{\sigma }_{\mathit{新航}}〉$ 在相同的级联级数上平均的镍表面碰撞级联 $\left(Ë，Ť\right)$在相同的模拟条件下，该值要比在大多数材料中碰撞级联中生成的值高。表面级联中产生的点缺陷主要聚集成簇。由于碰撞级联与自由表面的相互作用而导致的空位和SIA的空间分离是导致金属表面数量增加的主要驱动机制。$〈{ñ}_{\mathit{FP}}〉，〈{\sigma }_{\mathit{真空}}〉$ 和 $〈{\sigma }_{\mathit{新航}}〉$ 在镍表面碰撞小瀑布中产生。