用改进分析型嵌入原子法计算金属钼中刃位错的弛豫结构和应变能

CALCULATIONS OF THE RELAXED STRUCTURE AND STRAIN ENERGY OF EDGE DISLOCATION IN METAL Mo BY MODIFIED ANALYTICAL EMBEDDED-ATOM METHOD

把MAEAM与MD模拟方法相结合,以Mo为例从原子尺度对bcc金属中的a【100】刃位错的弛豫结构和应变能进行了计算机模拟．结果表明：其弛豫结构具有C_2V点群对称性；当离位错线的径向距离R(?)1．5b=0．472nm时,单位长度位错线的应变能E_s与In(R/26)成线性关系,由此确定的位错芯区半径r_c=0．472nm,由线性拟合的截距和斜率确定的位错芯区的畸变能E_(core)=16．334 eV/nm；确定能量表达式中的系数K=105．6 eV/nm^3,接近弹性理论的计算值(K= (μ)/(4π(1-v))=88 eV/nm^3)．

Combining MAEAM with MD simulation method, both the relaxed structure and strain energy of an a[100] edge dislocation in metal Mo have been simulated systematically in atomic scales. The results show that the relaxed structure has a C2v point group symmetry, and the calculated strain energy E8 per unit length of the dislocation is a linear function of ln（R/2b） when the radial distance R ≥ 1.5b=0.472 nm, thus the corresponding core radius rc=0.472 nm. From intercept and slope of the straight line fitting those data corresponding to the outside of the dislocation core, the dislocation core energy Ecore=16.334 eV/nm and the coefficient in energy expression K=105.6 eV/nm^3 were obtained, the latter nears the predicted value by elasticity theory （K=μ/4π（1-v）=88eV/nm^3）.