Evolution of microstructure and creep rupture properties for a low-cost Ni-basedsingle crystal superalloy during long-term aging at 1050 ℃

doi:10.13251/j.issn.0254-6051.2025.05.018

Abstract

Abstract: A low-Re nickel-based single crystal superalloy was subjected to long-term aging treatment at 1050 ℃ for 50, 100, 200, 500 and 1000 h after standard heat treatment (1275 ℃×2 h+1290 ℃×2 h+1310 ℃×10 h+1315 ℃×8 h, AC+1100 ℃×4 h, AC+870 ℃×20 h, AC). Scanning electron microscope (SEM) was used to observe the microstructure of the alloy after standard heat treatment and long-term aging for different time. The creep rupture properties of the alloy after standard heat treatment and long-term aging were tested under the condition of 1038 ℃/172 MPa. The effect mechanism of long-term aging on the creep rupture lives of the alloy was investigated. The results show that the regular cubic γ′ phase structure is obtained after standard heat treatment. During long-term aging at 1050 ℃, the size of γ′ phase gradually increases, and γ′ phase merges and connects, even rafts after long-term aging for 500 h. Until aging for 1000 h, the TCP phase is not precipitated in the alloy. The creep rupture life of the alloy after long-term aging for 200 h is longer than that of the standard heat treated, and then the creep rupture lives of the alloy aged for 500 h and 1000 h gradually decrease. This is due to interfacial dislocation networks formed in the standard heat treated and long-term aged alloy during creep rupture tests. The interfacial dislocation networks increase after aging for 200 h, while then decrease after aging for 1000 h.

Key words: Ni-based single crystal superalloy, long-term aging, γ′ phase, creep rupture properties, dislocation

CLC Number:

TG146

Liang Shuang, Liu Zhixin, Guo Shengdong, Liu Lirong. Evolution of microstructure and creep rupture properties for a low-cost Ni-basedsingle crystal superalloy during long-term aging at 1050 ℃[J]. Heat Treatment of Metals, 2025, 50(5): 111-115.

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