低Re镍基单晶高温合金平衡相析出行为的热力学模拟计算

Thermodynamic Simulation Calculation on Precipitation Behavior of Equilibrium Phases in a Low Re-bearing Nickel-based Single Crystal Superalloy

摘要:

基于Pandat热力学计算软件及PanNi数据库, 采用热力学相平衡计算方法, 研究了合金成分对低铼DD6合金平衡相析出行为的影响。结果表明: DD6合金平衡相主要为γ相、γ′相、μ相及碳化物MC和M₂₃C₆, 计算结果与实验结果吻合。γ′相析出量主要由Al、Ta和Nb含量控制, 随Al、Ta和Nb含量增加, γ′相析出量显著增加, 固溶温度明显升高, 液相初凝与终凝温度逐渐降低。C含量决定MC和M23C6的析出量, MC和M₂₃C₆析出量随C含量增加而增大。μ相析出主要受Re、W、Mo和Cr的影响, 随Re、W、Mo和Cr含量增加, μ相开始析出温度显著升高, 析出温度范围明显变宽, 最大析出量明显增大。

Abstract:

Based on thermodynamic calculation Pandat software and PanNi database, thermodynamic phase equilibrium calculation method was employed to investigate the effect of alloying composition on precipitation behavior of equilibrium phases in a low Re-containing nickel-based single crystal superalloy DD6. Results indicate that the equilibrium phases consist of γ, γ′, μ, MC and M₂₃C₆, and the calculated results are in excellent agreement with the experimental results. The Al, Ta and Nb content mainly control the mass fraction of γ′ precipitates. With increase of Al, Ta and Nb content, the mass fraction of γ′ precipitates is significantly enhanced, the solution temperature of γ′ precipitates is obviously increased, and the liquid starting and finishing solidification temperature is gradually decreased. The C content determines the precipitation amount of MC and M₂₃C₆. Increment of C content results in more precipitation of carbides. The precipitation of μ phase is predominantly influenced by Re, W, Mo and Cr. With the increase of Re, W, Mo and Cr content, the initial precipitation temperature of μ phase is significantly enhanced, the maximum precipitation amount of μ phase is obviously increased, and the precipitation temperature range of μ phase is markedly extended.