镍基高温合金GH4706析出相的热力学计算与分析

应用Thermo-Calc热力学计算软件,模拟元素含量及热处理温度对镍基高温合金GH4706平衡相析出规律的影响。结果表明:平衡析出相的种类和析出温度范围与微观组织观测和差热分析的实验结果基本一致。MC碳化物的初始析出温度随Nb、Ti含量增加而降低,而析出量主要受C含量影响;η相初始析出温度与析出量随Ti含量增加而增大,受Nb、Fe影响较小;γ'相初始析出温度与析出量随Al含量增加而升高,受Ti、Nb含量影响较小;合金凝固过程中Nb、Ti会产生显著正偏析,Cr产生负偏析;Nb、Ti含量增加提高合金初熔点,降低合金的终熔点,使凝固温度范围变窄。

Thermodynamic calculation and theoretical analysis of equilibrium precipitation phases in Ni-based superalloy GH4706

The effects of alloying elements and heat treatment temperature on equilibrium precipitation phases in Nibased GH4706 superalloy were simulated by Thermo-Calc software.The results show that the equilibrium precipitation phases obtained by calculation are consistent with the experimental results obtained by microstructural observations and differential thermal analysis.With increasing Nb and Ti contents,precipitating temperature of MC decreases,but the mass fraction of MC depends upon the C content.Initial precipitating temperature and mass fraction of η phase increase with increasing the Ti content,but are slightly affected by Nb and Fe contents;the content and initial precipitating temperature of γ'phase increase with increasing the Al content,but are slightly affected by Ti and Nb contents;significant positive segregation of Nb and Ti and negative segregation of Cr are observed during non-equilibrium solidification process.Moreover,with increasing the Nb and Ti contents,initial melting points increases,final melting points and liquid-solid temperature range decrease.