首页|The impact of grain boundary serration treatments on the creep deformation of Udimet-720Li superalloy

The impact of grain boundary serration treatments on the creep deformation of Udimet-720Li superalloy

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  • Elsevier
The influence of grain boundary serration treatments on the microstructure and creep behavior of Udimet-720Li superalloy was investigated. The cooling rate of super γ' solvus heat treatment has a profound impact on γ' precipitation and its interactions with grain boundaries. While air cooling yielded straight grain boundaries, slower cooling processes altered the morphologies of grain boundaries into Type-Ⅰ with moderate undulation due to continuous γ' precipitation and Type-Ⅱ with pronounced undulation due to discontinuous cellular γ/γ' formation. Creep tests at 700 ℃/700 MPa were conducted on samples with straight boundaries (STB), Type-Ⅰ serration (SRB-Ⅰ), and Type-II serration (SRB-2). Compared to the STB sample, the SRB-Ⅰ sample showed an improved creep resistance, exhibiting a minimum creep rate of 2.66 × 10~(-7) s~(-1) and a 17 % extended rupture life. This improvement is attributed to the higher fractions of secondary and tertiary γ', which effectively hinder dislocation motion, and the presence of Type-Ⅰ grain boundary serration, which deflects crack propagation. By contrast, the SRB-2 sample exhibited a higher minimum creep rate of 1.74 × 10~(-6) s~(-1) and a 42 % shorter rupture life than the STB sample. Although Type-Ⅱ serration exhibited more pronounced boundary undulation than Type-I serration, the incoherent flowery γ' particles and cellular structure reduced its impedance to dislocation motion, leading to a higher creep strain rate. The less cohesive grain boundaries caused by cellular γ/γ' precipitates also facilitated void nucleation and microcrack formation, accelerating the onset of tertiary creep. This study demonstrates that Type-Ⅰ grain boundary serration treatment can significantly improve the creep resistance of Udimet-720Li superalloy.

SuperalloysHeat treatmentγ' precipitatesSerrated grain boundaryCreep properties

Tso-Wei Chen、Bo-Chen Wu、Yung-Chang Rang、Hideyuki Murakami、Yoshiaki Toda、Tsai-Fu Chung、R. Devesh Kumar Misra、An-Chou Yeh

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Program in Prospective Functional Materials Industry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 30044, Taiwan, ROC||High Entropy Materials Center, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 300044, Taiwan, ROC

S-Tech Corporation, 15, Cong 1st Road, Environmental Science and Technology Park, Liouying District, Tainan, 73659, Taiwan, ROC

Gloria Material Technology Corporation, 10, Gong 2nd Road, liuying District, Tainan, 73659, Taiwan, ROC

Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 305-0047, Japan

Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC

Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX, 79968, USA

Program in Prospective Functional Materials Industry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 30044, Taiwan, ROC||High Entropy Materials Center, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 300044, Taiwan, ROC||Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 300044, Taiwan, ROC

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2025

10.1016/j.msea.2024.147729

Materials science and engineering, A. Structural materials

Materials science and engineering, A. Structural materials

ISSN：0921-5093
年,卷(期)：2025.924(Feb.)
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