辐照条件下SiC晶界导热性能的分子动力学分析

Effect of Irradiation on the Grain Boundary Thermal Conductivity of SiC:a Molecular Dynamics Study

SiC材料由于具有优良的物理化学性质而在工程领域得到广泛应用。但在辐照条件下,Frenkel缺陷势必影响材料的宏观性质。尤其在核能工程领域,辐照无法避免,而传热性质是材料的关键性质之一。本文采用分子动力学方法模拟了SiC材料晶界导热性质在辐照缺陷存在条件下的变化规律。研究结果表明,晶界扭转角度越大,界面能也越大,并且界面热阻大致与界面能呈正比关系。辐照缺陷的存在使界面热阻增加了一个数量级。声子态密度分析结果表明,界面附近原子晶格失配程度增加是导致辐照后界面热阻进一步增加的原因。

SiC is widely used in industry due to exposed to irradiation, Frenkel defects induced by properties of the material. In particular, when SiC is its excellent physical and chemical properties. When it is the irradiation will significantly alter the macroscopic used as nuclear engineering components, it is impossible to avoid irradiation, where macroscopic properties of the materials, such as thermal conductivity, are also critical. In this work, molecular dynamics study has been conducted on the grain boundary thermal conductivity of SiC under irradiation condition. Nine twist grain boundary models were created and rNEMD method was employed to calculate grain boundary thermal resistance. Results show that interracial energy increases with increasing grain boundary twist angle, which is also proportional to the interfacial thermal resistance. Due to the presence of irradiation defects, the interracial thermal resistance increases by one order of magnitude compared to the un-irradiated counterpart. It is believed that this is due to the lattice mismatch induced by the extensive irradiation defects near the grain boundary, as revealed by the vibrational density of states analysis.