中子辐照引起的位移级联能在金属中产生各种缺陷.通过三维分子动力学方法模拟了bcc-Fe在不同空位浓度下中子辐照的位移级联过程.模拟结果表明,在空位浓度0％和初始碰撞原子能量5keV的情形下,位移级联过程会出现大量空位、间隙原子团等缺陷.经过0.5ps后点缺陷数量NF达到最大值1632,之后其逐渐减少,10ps后稳定在60.预置空位的存在加速了级联过程中点缺陷的湮灭.进一步的模拟指出,预置空位浓度越高,则点缺陷复合也就越快.这些结果有助于描述核反应堆结构钢的某些微观失效机理.%The neutron irradiation on metal materials could generate various defects which are caused by displacement cascades. The displacement cascades of neutron irradiation with various vacancy concentrations in bcc-Fe are simulated by three-dimensional molecular dynamics method. The simulation results show that a large number of vacancies and self interstitial atoms (SIAs) clusters would appear for the case of 0% vacancy concentration and 5keV primary knock-on atom energy. The number of point defect NF reached to peak value 1632 after 0. 5ps. It will decrease sequently and the number of point defect will go stable value 60 after 10 ps. The existence of pre-vacancy defects would accelerate the defect annihilation in the cascade process. The further simulation indicated that the defect annihilation is the faster in the case of the higher pre-vacancy concentration. These results could be useful for describing some mechanism of microcosmic failure for structural steels components in nuclear reactors.
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