中文摘要：

建立了用于计算γ′-Ni3Al和γ″-Ni3Nb成分及含量的最优化数学模型，证明了通过复相分离法（MulIiple Phases Separation Method，以下简称MPSM）计算两相成分及含量的可行性和准确性，利用MPSM法计算了调整（Al＋Ti）／Nb比值后析出相的成分、含量及分配量，解释了调整该比值对改型IN718合金高温稳定性影响的原因。

英文摘要：

An optimized mathematical model was established to calculate the composition and volume fraction of γ′-Ni3Al and γ″-Ni3Nb phases in IN718 alloy. The feasibility and accuracy of MPSM to calculate the composition and volume fraction of these two phases were also demonstrated. The composition, volume fraction and elemental partitioning fraction of the two precipitated phases after adjusting （Ti＋Al）/Nb value in γ′,γ″ and γ mixture were calculated through the application of MPSM method. The reason why the adjustment could affect the high-temperature stability of modified IN718 alloys was also explained.