Formation of eta phase during aging at 750–850 °C for Ni-base superalloys with different Ti/Al ratios

IF 1.9 3区材料科学 Q4 CHEMISTRY, PHYSICAL Calphad-computer Coupling of Phase Diagrams and Thermochemistry Pub Date : 2024-09-10 DOI:10.1016/j.calphad.2024.102743

Dong-Ju Chu , Chanhee Park , Joonho Lee , Woo-Sang Jung

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Abstract

The formation of the η phase in two nickel-based superalloys that have similar amounts of titanium and aluminum but different Ti/Al ratios was investigated. The aging was carried out at 750 °C, 800 °C, and 850 °C for 10000 h. The microstructures were observed using SEM and TEM, and equilibria phases were calculated using a Thermo-Calc. equipped with TCNI11 database. Results showed that the number and size of η phase increased with aging temperature and Ti/Al ratios. The size of the γ′ phase was also found to be increased with aging temperature, but it was not significantly affected by the Ti/Al atomic ratio. However, the η phase was not predicted to be the thermodynamic equilibrium phase in the alloy using Thermo-Calc. with the TCNI11 database. The η phase was expected to be the equilibrium phase with Ti/Al ratios higher than 1.85 at 850 °C for Ni-27.0Cr-19.1Co-0.91Nb-0.29Mo-0.14C-xTi-yAl alloys. However, the result does not match the experimental observations or other literature. It is suggested that the effect of titanium on the formation of the η phase may be underestimated in the TCNI11 database. Therefore, it is necessary to enhance the accuracy of predicting the formation of the η phase by modifying at least one of the thermodynamic parameters, including the phase equilibrium of the ternary Ni-Ti-Al system.

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不同钛/铝比例的镍基超合金在 750-850 °C老化过程中形成的乙太相

研究了钛和铝含量相似但钛/铝比例不同的两种镍基超级合金中 η 相的形成。使用 SEM 和 TEM 观察了微观结构，并使用配备 TCNI11 数据库的 Thermo-Calc 计算了平衡相。结果表明，η 相的数量和大小随老化温度和钛/铝比率的增加而增加。γ′相的尺寸也随着老化温度的升高而增大，但受 Ti/Al 原子比的影响不大。然而，使用 TCNI11 数据库的 Thermo-Calc 预测合金中的η相并不是热力学平衡相。对于镍-27.0Cr-19.1Co-0.91Nb-0.29Mo-0.14C-xTi-y-Al 合金，当 Ti/Al 比率高于 1.85 时，η 相预计将在 850 °C 时成为平衡相。然而，这一结果与实验观察或其他文献不符。这表明 TCNI11 数据库可能低估了钛对η相形成的影响。因此，有必要通过修改至少一个热力学参数（包括三元镍-钛-铝体系的相平衡）来提高预测 η 相形成的准确性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Calphad-computer Coupling of Phase Diagrams and Thermochemistry 化学-热力学

CiteScore

4.00

自引率

16.70%

发文量

审稿时长

2.5 months

期刊介绍： The design of industrial processes requires reliable thermodynamic data. CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) aims to promote computational thermodynamics through development of models to represent thermodynamic properties for various phases which permit prediction of properties of multicomponent systems from those of binary and ternary subsystems, critical assessment of data and their incorporation into self-consistent databases, development of software to optimize and derive thermodynamic parameters and the development and use of databanks for calculations to improve understanding of various industrial and technological processes. This work is disseminated through the CALPHAD journal and its annual conference.