难变形高温合金GH720Li平衡析出相的热力学计算

Thermodynamic Calculation on Equilibrium Precipitated Phases in GH720Li Superalloy

摘要:

为了给热处理制度和热加工工艺提供理论依据，采用Thermo-Calc热力学计算软件，对GH720Li合金平衡析出相和非平衡凝固进行模拟计算分析。结果表明，合金凝固过程中Mo、Ti偏析比较严重，并给出Ti、Al含量对γ'相析出温度和析出量的定量计算结果。C含量的增加可以显著提高碳化物的析出量，但对碳化物的析出温度无影响；Cr对M23C6的析出量没有影响，但显著提高其析出温度。进一步对一次碳化物MC的析出温度与合金初熔点的关系进行定量计算。

Abstract:

In order to provide theoretical guidance for hot working and heat treatment, the equilibrium precipitated phases and the effect of elements on the thermodynamic equilibrium phases for GH720Li superalloy were studied by Thermo-Calc software. The calculated results show that there is serious segregation of Mo and Ti during the solidification of the superalloy. The quantitative rule of the contents of Al and Ti on the precipitation temperature and mass fraction of γ' phase is presented. Increment of C content leads to more precipitation of carbides, but it has no effect on their precipitation temperatures. Cr can not change the precipitation content of M23C6, but it can increase the precipitation temperature remarkably. Furthermore, the relation between the precipitated temperature of MC and initial melting point of GH720Li superalloy was studied.