晶界空位与碳原子对铁晶界力学性能的影响

 为了从纳米尺度上探究与表征bcc-Fe的晶界变形行为,采用分子动力学方法分析了4种不同的bcc-FeΣ3晶界(Σ3(111)、Σ3(112)、Σ3(111)/(115)、Σ3(112)/(552))的拉伸与剪切变形过程,研究了晶界上空位和碳的原子分数对晶界拉伸和剪切性能的影响。结果表明,随着空位与碳原子所占晶界原子分数的增加,Σ3(112)晶界的拉伸应力-应变曲线屈服阶段逐渐消失。随着空位原子分数的升高,Σ3(111)晶界抗拉强度逐渐降低,而其余3种晶界抗拉强度也有不同程度的减小。含碳原子的Σ3(111)晶界抗拉强度有所增加,相反,其余3种晶界抗拉强度均低于原始无缺陷晶界。4种晶界的剪切强度均由于空位的存在或碳原子置换而明显减小。

Effects of vacancies and C atoms on mechanical properties of Fe grain boundary

In order to explore and characterize the deformation behavior of bcc-Fe grain boundaries from the nanoscale,the tensile and shear deformation processes of four different bcc-Fe Σ3 grain boundaries,i.e. Σ3(111),Σ3(112),Σ3(111)/(115) and Σ3(112)/(552),are investigated by molecular dynamics simulation. The effect of the vacancies and C atoms with different atomic percents on the machanical properties of the four different grain boundaries are discussed. The results indicate that the tensile stress-strain curve yield stage of Σ3(112) grain boundary gradually disappears due to the increase of the atomic percent of the grain boundary occupied by vacancies and C atoms.The tensile strength of Σ3(111)grain boundary gradually decreases with the increases of the atomic percent of vacancies,and the tensile strength of the other three grain boundaries are reduced in different degree. The tensile strength of Σ3(111) grain boundary containing C atoms increases,however,the other three grain boundary tensile strengths are lower than the original defect-free grain boundaries. The shear strength of the four grain boundaries is significantly reduced by the presence of vacancies or the replacement of C atoms.