摘要
分别建立了有序结构γ′相亚点阵中原子置换行为引起的体应变最小和不同密排方向上原子尺寸失配度最小的目标函数,并给出了两个亚点阵(顶角与面心)之间元素含量平衡分配及其范围的约束条件.以单晶合金CMSX-2和SRR99为对象,使用Powell和出Simplex复合优化算法,分别计算了γ′相单位晶胞两个亚点阵中的元素浓度(原子位置浓度)和亚点阵分数(单位晶胞内顶角和面心原子各占百分数);此外,建立了已知亚点阵元素浓度计算γ′相点阵常数的算式,并将其分别用于Ni_3Al和上述两种合金γ′相的点阵常数计算.将上述计算结果与用原子探针场离子显微分析导出的元素出现概率法所得亚点阵元素浓度进行了比较,并将计算与报道所得γ′相点阵常数进行了比较,吻合性良好.从而,给出了一种只需知道有序结构相成分,即可测算其单位晶胞中亚点阵元素浓度及点阵常数的新方法.
Objective functions on minimizing the atomic volume elastic strain and the atomic
size misfit in close--packed directions due to the atomic substitution in sublattices of γ' phase are
established, respectively. Constrain conditions on equilibrium partition of a1loying elements and on
their concentration range in sublattices of γ' phase are correspondingly built up. Using superalloys
CMSX--2 and SRR99 as objects investigated and adopting a compound optimization calculation method
with the Powell and the Simplex algorithms, the elemental concentration and the site fraction of the
two sublattices can be calculated. In addition, a calculation formula on lattice parameter of γ' phase
closely associated with the elemeotal concentration and with the site occupancy of the sublattices is
derived. All the calculated results by use of the present methods show quite good accordance with the
reported values. The method proposed can predict the elemental concentration in sublattices and the
lattice parameter of γ' phase when the chemical composition of the γ' phase investigated is known.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第6期569-573,共5页
Acta Metallurgica Sinica
基金
国家自然科学基金50071042
关键词
镍基合金
Γ相
优化计算
亚点阵浓度
点阵常数
Ni base alloy
γ’phase
optimizing calculation
elemental concentration in sublattice
lattice parameter
