氧含量对碳化硅晶体的拉伸性能的影响

Effect of Oxygen Content on the Tensile Properties of SiC

碳化硅具有良好的抗腐蚀和抗氧化性能,是先进核反应堆核燃料包壳的候选材料之一,但杂质元素会对碳化硅材料的机械性能产生重要影响。杂质元素对材料拉伸性能的影响可用第一性原理进行分析。首先构建一个2×2×2的3C-SiC超晶胞结构,使用VASP(Vienna Ab-initio Simulation Package)程序模拟SiC晶体的理想拉伸过程;在不同间隙位增加1个或2个氧原子,构建不同的碳化硅晶胞模型,并计算含氧SiC晶体拉伸强度;通过模拟计算了一个掺杂原子和两个掺杂原子在不同间隙位的拉伸强度,最后总结含氧量对SiC拉伸强度的影响。计算结果表明,掺氧后SiC材料更容易发生脆性断裂,同时氧原子增加后SiC的抗拉强度变小了,说明氧含量对SiC的拉伸性能有明显影响。

SiC is one of the candidate cladding materials for the advanced nuclear reactor and has a strong resistance to corrosion and oxidation. The impurities in SiC may have a significant effect on the mechanical properties. The tensile strength of SiC was studied by Ab-initio method. By VASP, a 3C-SiC supercell was built in 2 × 2 × 2. The ideal tensile process of oxygen doped SiC was simulated by VASP. The effects of oxygen on the tensile properties were studied. The tensile strength of supercells with one or two oxygen atom in different interstitial sites was simulated. The effect of oxygen content on the tensile strength was summarized. The results show that the doped oxygen makes SiC materials more fragile and easier to crack, and the tensile strength decreases with the increase of oxygen content. This indicates that the oxygen content has a significant effect on the tensile properties of SiC.