Evaluation on elevated-temperature stability of modified 718-type alloys with varied phase configurations
来源期刊：International Journal of Minerals Metallurgy and Materials2020年第8期
论文作者：Zhan Qiao Chong Li Hong-jun Zhang Hong-yan Liang Yong-chang Liu Yong Zhang
文章页码：1123 - 1132
摘 要：Inconel 718 is a Ni–Fe-based superalloy widely used in aerospace engines because of its excellent mechanical properties. However,the inferior stability of the γ″ phase limits the application of Inconel 718, which coarsens rapidly at temperatures greater than 650°C. Further improving the temperature tolerance of Inconel 718 requires optimization of the phase configuration via modification of the alloy’s chemical composition. Given the aforementioned objective, this work was conducted to study the precipitation behavior and thermal stability of the strengthening phases with various structures in modified Inconel 718 alloys by tailoring the Al/Ti ratio. With increasing Al/Ti ratio, three particle configurations were formed: γ′/γ″ composite, isolated γ′, and γ′/γ″/γ′ composite particles. The results of aging tests demonstrate that the isolated γ′ and the γ′/γ″/γ′ composite structure exhibited better thermal stability at temperature as high as 800°C. The isolated γ′ exhibited a reduced coarsening rate compared with the γ′/γ″/γ′ composite particles because the isolated γ′ phase was rich in Al, Ti, and Nb. However, the γ′/γ″composite particles coarsened and decomposed rapidly during aging at temperatures greater than 700°C because of the lower stability resulting from the larger number of γ″ particles. The obtained results provide necessary data for the compositional optimization of novel 718-type alloys.
Zhan Qiao1，Chong Li1，Hong-jun Zhang2，Hong-yan Liang1，Yong-chang Liu1，Yong Zhang3
1. State Key Lab of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University2. Key Laboratory of the Ministry of Education for Modern Metallurgy Technology, North China University of Science and Technology3. Science and Technology on Advanced High Temperature Structural Materials Laboratory, AEEC Beijing Institute of Aeronautical Materials
摘 要：Inconel 718 is a Ni–Fe-based superalloy widely used in aerospace engines because of its excellent mechanical properties. However,the inferior stability of the γ″ phase limits the application of Inconel 718, which coarsens rapidly at temperatures greater than 650°C. Further improving the temperature tolerance of Inconel 718 requires optimization of the phase configuration via modification of the alloy’s chemical composition. Given the aforementioned objective, this work was conducted to study the precipitation behavior and thermal stability of the strengthening phases with various structures in modified Inconel 718 alloys by tailoring the Al/Ti ratio. With increasing Al/Ti ratio, three particle configurations were formed: γ′/γ″ composite, isolated γ′, and γ′/γ″/γ′ composite particles. The results of aging tests demonstrate that the isolated γ′ and the γ′/γ″/γ′ composite structure exhibited better thermal stability at temperature as high as 800°C. The isolated γ′ exhibited a reduced coarsening rate compared with the γ′/γ″/γ′ composite particles because the isolated γ′ phase was rich in Al, Ti, and Nb. However, the γ′/γ″composite particles coarsened and decomposed rapidly during aging at temperatures greater than 700°C because of the lower stability resulting from the larger number of γ″ particles. The obtained results provide necessary data for the compositional optimization of novel 718-type alloys.
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