用分子动力学方法研究了不同温度下无定形Si-C、Si-B-C体系的扩散行为, 分析掺杂B原子对体系热稳定性及高温抗蠕变性的影响. 基于UFF力场, 在300、773、1273、1773及2073K下, 用分子动力学方法计算并比较了它们的MSD曲线及扩散系数, 分析温度对原子自扩散的影响. 无定形体系引入B原子后, 原子自扩散系数降低; 随温度升高, 自扩散系数缓慢上升, 接近2073K附近B原子的自扩散有明显加速趋势, 说明体系能够在2073K以下不发生相分离, 保持热稳定及良好的高温抗蠕变性.
Molecular dynamics simulations of amorphous Si-C and Si-B-C systems were carried out in order to investigate the diffusion behavior, and analyze the influence of the addition of B on the thermal stability and creep resistance at high temperature of the amorphous systems. Universal force field was used to describe atomic interactions in the systems at 300K, 773K, 1273K, 1773K and
2073K. MSD curves and diffusion constants at different temperatures were calculated and compared. After the addition of B in the amorphous Si-B-C system, self-diffusion constants of constituent atoms decreased at the same temperature, and increased with temperatures in both the amorphous systems. The results show that self-diffusion of B tends to ascend apparently up to 2073K, which accounts for that phase separation of the amorphous state would take place
at about 2073K. Below this temperature, the Si-B-C system will remain the thermal stability and good creep resistance.
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