The synergistic effect of Re and W on the evolution of TCP phases in Nickel-based superalloys

• Published in: Journal of alloys and compounds 2022-04, Vol.900, p.163286, Article 163286
• Main Authors: Wang, Yaxiao, Zhao, Manxiu, Li, Zhi, Li, Xiaobo, Yin, Fucheng, He, Jianing
• Format: Article
• Language: English
• Subjects: Aging; Aging (metallurgy); Differential thermal analysis; Evolution; Gamma-prime phase (crystals); Mathematical analysis; Mu phase; Nickel base alloys; Nickel-based superalloy; Performance prediction; Re, W; Slats; Superalloys; Synergistic effect; TCP phase; Transition temperature
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.163286

•The phase-transition temperature of the alloys are determined by means of TC and DTA.•The morphology and evolution of TCP phase are revealed.•The TCP phase gathered around the big blocky-like γ' phase will lead to the formation of the holes in the alloy.•There is a coherent relationship between the μ/P intergrowth phases, whose crystallography orientation relationships are determined.•The big blocky-like γ' phases and gathered TCP phases can be eliminated by solution-aging treatment. In this work, the synergistic effect of Re and W on the evolution of the topological close-packed phases (TCP) in Nickel-based superalloys were studied by means of Thermo-Calculation (TC), solidifying slowly, Differential Thermal Analysis (DTA), and solution-aging treatment. The specimens were analyzed by means of SEM-EDS, TEM-SADP, and EPMA. The calculated results indicated that the P phase precipitated prior to the μ phase with the temperature decrease, and both phases μ and P coexisted in a certain temperature range when the content of Re was higher ( Re: 5–7 wt%) and the content of W was lower ( W:4–6 wt%); Only phase μ precipitated from the alloy when Re content was less than 4 wt% and W content was higher than 7 wt%. The experimental results showed that the μ phases were slats-like and distributed in parallel in different orientations; and the μ/P intergrowth phases with coherent relationship were short rod-like. In addition, the gathered μ/P intergrowth phases around the big blocky-like γ' phases were found in alloys solidified slowly, which was prone to cause holes. Based on phase-transition temperature obtained by combining calculation and DTA, the solution-aging process of the alloys were determined. After solution-aging treatment, the long strip shape μ phases and short rod-like μ/P intergrowth phases distributed uniformly in the matrix, and the big blocky-like γ' phases and holes disappeared. The experimental results showed that the total amount of TCP phase decreased and the P phase gradually disappeared when the content of Re decreased and the content of W increased. The research results had a guiding role in optimizing the composition of alloys and predicting the safety performance of aerocraft during the flight cycle.