超温热暴露对铸造 TiAl-4822 合金显微组织和力学性能的影响

Effects of hyperthermal exposure on microstructures and mechanical properties of casting TiAl-4822 alloys

摘要

探讨 Ti-48Al-2Cr-2Nb 合金（简称为 4822 合金）在 800～950 ℃短时超温热暴露后显微组织和力学性能的变化规律，研究热暴露温度和时间对 4822 合金显微组织，室、高温拉伸性能及高温持久性能的影响。结果表明，800～950 ℃超温热暴露后 4822 合金组织中 α₂/γ 片层团中 α₂ 相溶解形成粗大的 γ 片层。随着温度的提升，α₂ 相溶解数量越来越多，α₂/γ 片层组织末端粗化，且向相邻片层生长。900 ℃热暴露后在片层团与等轴 γ 晶粒的边界处有球形 B2 相析出，950 ℃热暴露后片层团内粗大的 γ 片层内部析出细小的 B2 相，B2 相数量增多。随着热暴露时间的延长，块状 α₂ 相内析出极细的 γ 片层且数量增加，片层团晶界处出现的等轴 γ 晶粒逐步长大，片层团内部出现的等轴 γ 晶粒数量增多。经 850 ℃/10 min、850 ℃/120 min、900 ℃/10 min 热暴露后，合金的室、高温屈服强度均增加，室、高温断后伸长率均下降，950 ℃/10 min 热暴露后合金的室、温断后伸长率为（2.4±0.55）%，比原始状态提升 5.73%；经 850 ℃/10 min、850 ℃/120 min、900 ℃/10 min 热暴露后合金在 650 ℃/400 MPa 条件和 700 ℃/350 MPa 条件的持久寿命均增加，但在 850 ℃/120 min 热暴露后合金在 650 ℃/400 MPa 条件下的持久寿命为（14.85±3.55）h，比原始状态下降 94.02%。

Abstract

This work investigates the alterations in the microstructure and mechanical properties of the Ti-48Al-2Cr-2Nb alloy (referred to as 4822 alloy) following simulated short-term superheated service at 800-950 ℃. The research focuses on the effects of thermal exposure temperature and holding time on the microstructure, room-temperature and high-temperature tensile properties, and high-temperature endurance properties of 4822 alloy. The results reveal that after exposure at 800-950 ℃, the α ₂ phase within the α₂/γ lamellar colonies dissolves, forming coarse γ lamellae. As the thermal exposure time increases, the dissolution of the α₂ phase becomes more pronounced, the ends of the α₂/γ lamellar structures coarsen, and the lamellae grow into adjacent colonies. After treatment at 900 ℃, spherical B2 precipitates form at the boundaries between lamellar colonies and equiaxed γ grains. At 950 ℃, fine B2 precipitates appear within the coarse γ lamellae inside the colonies, and the number of B2 precipitates increases. Prolonging the exposure time leads to the precipitation of extremely fine γ lamellae within blocky α₂ phases, with their quantity increasing; equiaxed γ grains at colony boundaries gradually grow, and the number of equiaxed γ grains within the colonies also rises. After thermal exposure at 850 ℃/10 min, 850 ℃/120 min, and 900 ℃/10 min, both the room and high-temperature yield strengths of the alloy increase, while the room and high-temperature elongations decrease. However, after thermal exposure at 950 ℃/10 min, the room-temperature elongation of the alloy is (2.4±0.55)%, representing an increase of 5.73% compared to its original state. After thermal exposure at 850 ℃/10 min, 850 ℃/120 min, and 900 ℃/10 min, the stress rupture lives of the alloy under both 650 ℃/400 MPa and 700 ℃/350 MPa conditions are extended. However, after thermal exposure at 850 ℃/120 min, the stress rupture life under 650 ℃/400 MPa is (14.85±3.55) h, which decreased by 94.02% compared to its original state.

关键词

Ti-Al 系金属间化合物 / 热暴露 / TiAl 合金 / 精密铸造 / 显微组织 / 力学性能

Key words

Ti-Al intermetallics / thermal exposure / TiAl alloy / precision casting / microstructure / mechanical property

参考文献

[1] Jarvis D J, Voss D. IMPRESS integrated project: an overview paper[J].Materials Science and Engineering: A, 2005, 413/414: 585-591.

[2] 黄伯云 . 钛铝基金属间化合物[M].长沙: 中南工业大学出版社, 1998.

[3] Chen G, Peng Y B, Zheng G, et al. Polysynthetic twinned TiAl single crystals for high—temperature applications[J].Nature Materials, 2016, 15(8): 876-881.

[4] Wang Q, Chen R R, Gong X, et al. Microstructure, mechanical properties, and crack propagation behavior in high—Nb TiAl alloys by directional solidification[J].Metallurgical and Materials Transactions A, 2018, 49(10): 4555-4564.

[5] Liu D L, Mu R D, He L M, et al. Failure behaviour of EB—PVD YSZ thermal barrier coatings under simulated aero—engine operating conditions[J].Surface and Coatings Technology, 2023, 474: 130027.

[6] Τawancy Η Μ, Al—Hadhrami L M. Degradation of turbine blades and vanes by overheating in a power station[J].Engineering Failure Analysis, 2009, 16(1): 27-280.

[7] 余竹焕, 刘蓓蕾, 王盼航, 等 . 热腐蚀对高温合金力学性能的影响以及防护措施的研究进展[J].铸造, 2019, 68(6): 550-557.

[8] Yu Z H, Liu B L, Wang P H, et al. Research progress on the influence of hot corrosion on mechanical properties of superalloys and protective measures[J].Foundry, 2019, 68(6): 550-557.

[9] Tong J Y, Ding X F, Wang M L, et al. Assessment of service induced degradation of microstructure and properties in turbine blades made of GH4037 alloy[J].Journal of Alloys and Compounds, 2016, 657: 777-786.

[10] Clemens H, Kestler H . Processing and applications of intermetallic γ—TiAl—based alloys[J].Advanced Engineering Materials, 2000, 2(9): 551-570.

[11] Staneková H, Lapin J. Creep damage characterisation of intermetallic Ti—46Al—8Ta alloy under thermal cycling creep[J].Kovové Materiály, 2013, 124(3): 485-490.

[12] 安文瑞, 郑为为, 郑运荣, 等 . 短时超温对定向凝固 DZ125 合金微观组织和拉伸性能的影响[J].稀有金属, 2020, 44(10): 1009-1018.

[13] An W R, Zheng W W, Zheng Y R, et al. Overheating effect on microstructure and tensile property of directionally solidified DZ125 superalloy[J].Chinese Journal of Rare Metals, 2020, 44(10): 1009-1018.

[14] 崔若尧, 潘冬星, 刘志成, 等 . 短时过热对 DD6 镍基单晶高温合金蠕变性能的影响[J].材料开发与应用, 2024, 39(5): 79-85.

[15] Cui R Y, Pan D X, Liu Z C, et al. Investigation on effect of short—term overheating on creep properties of nickel—based single—crystal superalloy DD6[J].Development and Application of Materials, 2024, 39(5): 79-85.

[16] Giraud R, hervier Z, Cormier J, et al. Strain effect on the γ′ dissolution at high temperatures of a nickel—based single crystal superalloy[J].Metallurgical and Materials Transactions A, 2013, 44(1): 131-146.

[17] 刘明坤, 王威, 吴云胜, 等 . 超温及应力条件下 IC10 合金的组织演化及机理[J].材料工程, 2024, 52(7): 140-151.

[18] Liu M K, Wang W, Wu Y S, et al. Microstructure evolution and mechanism of IC10 alloy under over—temperature and stress condition[J].Journal of Materials Engineering, 2024, 52(7): 140-151.

[19] Ramanujan R V, Maziasz P J, Liu C T. The thermal stability of the microstructure of γ—based titanium aluminides[J].Acta Materialia, 1996, 44(7): 2611-2642.

[20] Beschliesser M, Chatterjee A, Lorich A, et al. Designed fully lamellar microstructures in a γ—TiAl based alloy: adjustment and microstructural changes upon long—term isothermal exposure at 700 and 800 ℃[J].Materials Science and Engineering: A, 2002, 329/330/331: 124-129.

[21] huang Z W, Cong T. Microstructural instability and embrittlement behaviour of an Al—lean, high—Nb γ—TiAl—based alloy subjected to a long—term thermal exposure in air[J].Intermetallics, 2010, 18(1): 161-172.

[22] 李臻熙, 曹春晓 . TiAl 合金全片层组织的热稳定性研究[J].中国材料进展, 2010, 29(3): 6-11.

[23] Li Z X, Cao C X. Thermal stability of fully lamellar microstructures in TiAl alloy[J].Materials China, 2010, 29(3): 6-11.

[24] 陈志元 . 具有微量钨硼钇的高铌 TiAl 合金的长期热稳定性研究[D].成都: 西南交通大学, 2020.

[25] Ding J, Zhang M H, Ye T, et al. Microstructure stability and micro—mechanical behavior of as—cast gamma—TiAl alloy during high—temperature low cycle fatigue[J].Acta Materialia, 2018, 145: 504-515.

[26] Kim Y Y. Microstructural evolution and mechanical properties of a forged gamma titanium aluminide alloy[J].Acta Metallurgica et Materialia, 1992, 40(6): 1121-1134.

[27] Bolz S, Oehring M, Lindemann J, et al. Microstructure and mechanical properties of a forged β—solidifying γ TiAl alloy in different heat treatment conditions[J].Intermetallics, 2015, 58: 71-83.

[28] Mitao S, Bendersky L A . Morphology and growth kinetics of discontinuous coarsening in fully lamellar Ti—44Al(at.%) alloy[J].Acta Materialia, 1997, 45(11): 4475-4489.

[29] Hu D, Godfrey A B, Loretto M H. Thermal stability of a fully lamellar Ti—48Al—2Cr—2Nb—1B alloy[J].Intermetallics, 1998, 6(5): 41-417.

[30] 高子彤, 胡锐, 吴与伦, 等 . TiAl 基合金片层结构粗化行为研究进展[J].稀有金属材料与工程, 2019, 48(9): 3071-3080.

[31] Gao Z T, Hu R, Wu Y L, et al. Research progress of lamellar structure coarsening behavior in TiAl based alloy[J].Rare Metal Materials and Engineering, 2019, 48(9): 3071-3080.

[32] Song L, Xu X J, You L, et al. Ordered α₂ to ωo phase transformations in high Nb—containing TiAl alloys[J].Acta Materialia, 2015, 91: 330-339.

[33] Maruyama K, Kim h Y, Zhu h L. Creep of lamellar TiAl alloys: degradation, stabilization and design of lamellar boundaries[J].Materials Science and Engineering: A, 2004, 387/388/389: 910-917.

[34] 曹春晓, 李臻熙, 孙福生 . Ti—48Al 合金片层组织的连续粗化机制[J].材料热处理学报, 2001, 22(1): 2-6.

[35] Cao C X, Li Z X, Sun F S. Continuous coarsening mechanism of lamellar microstructure in Ti—48Al alloy[J].Transactions of Materials and Heat Treatment, 2001, 22(1): 2-6.

[36] 汪小平, 郑运荣 . TiAl 基合金中的不连续粗化转变[J].材料工程, 2000, 28(7): 20-23.

[37] Wang X P, Zheng Y R. Discontinuous coarsening transformations in TiAl based alloys[J].Journal of Materials Engineering, 2000, 28(7): 20-23.

[38] 朱春雷, 李胜, 李海昭, 等 . 750 ℃热暴露对定向层片组织铸造 TiAl 合金室温拉伸塑性的影响[J].金属学报, 2014, 50(12): 1478-1484.

[39] Zhu C L, Li S, Li H Z, et al. Effect of thermal exposure at 750 ℃ on room temperature tensile ductility of cast TiAl alloy with directional lamellar microstructure[J].Acta Metallurgica Sinica, 2014, 50(12): 1478-1484.

[40] Wasz M L, Brotzen F R, Mclellan R B, et al. Oxygen embrittlement in titanium and titanium alloys[J].International Materials Reviews, 2018, 63(3): 181-208.

[41] Liu X, Song L. Synchrotron X—ray and neutron diffraction study on the deformation and phase transformation mechanisms in TiAl alloys: a review[J].Microstructures, 2025, 5: 2025093.

基金资助

国家自然科学基金(52371015)

稳定支持项目(KZ0C231525)