Evolution of Microstructure and Mechanical Properties of FGH4720Li P/M Superalloy Under Near-Service Conditions

doi:10.11900/0412.1961.2023.00188

Acta Metall Sin

2025, Vol. 61

Issue (6): 826-836 DOI: 10.11900/0412.1961.2023.00188

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Evolution of Microstructure and Mechanical Properties of FGH4720Li P/M Superalloy Under Near-Service Conditions

LI Dayu¹, YAO Zhihao¹(

), ZHAO Jie¹, DONG Jianxin¹, GUO Jing², ZHAO Yu²

1 School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
2 AECC Hunan Powerplant Research Institute, Zhuzhou 412002, China

Cite this article:

LI Dayu, YAO Zhihao, ZHAO Jie, DONG Jianxin, GUO Jing, ZHAO Yu. Evolution of Microstructure and Mechanical Properties of FGH4720Li P/M Superalloy Under Near-Service Conditions. Acta Metall Sin, 2025, 61(6): 826-836.

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Abstract

The FGH4720Li superalloy is produced by GH4720Li through the powder metallurgy (P/M) process, a method that effectively addresses the shortcomings of the original alloy production process, such as significant segregation, low alloying levels, and manufacturing difficulties. The P/M method also results in a finer and more uniform microstructure. However, during the service life of superalloys, the thermodynamic conditions can degrade the microstructure, potentially affecting their mechanical properties. There is currently limited research on how the microstructure and properties of FGH4720Li P/M superalloy evolve under near-service conditions. Therefore, it is essential to investigate this evolution to provide valuable insights for the manufacture of turbine disks. In this study, the microstructure evolution of FGH4720Li P/M superalloy and the variations in its yield strength have been examined after subjecting it to stress rupture for 500, 1000, and 2000 h at 600 and 650 ^oC under a stress level of 500 MPa. The results show that the yield strength of FGH4720Li P/M superalloy remains relatively high, at 1120 MPa, after stress rupture at 650 ^oC. Furthermore, the microstructure of FGH4720Li P/M superalloy undergoes a complex transformation during stress rupture. The secondary γ' phase's morphology gradually changes from an ellipsoidal shape to a flowerlike shape and ultimately to a cubic shape with rounded corners. The coarsening in the polymerization growth of tertiary γ' phases is also observed. To understand the changes in yield strength after stress rupture, a precipitation strengthening prediction model specifically designed for high γ' phase content and a multi-mode distribution of γ' phases was utilized. This calculation confirmed that the alteration in the content and size of the tertiary γ' phase is the primary factor responsible for the yield strength changes in the alloy.

Key words: P/M superalloy stress rupture test microstructure evolution yield strength

Received: 25 April 2023

ZTFLH:

TG132.3

Fund: National Natural Science Foundation of China(52271087);National Science and Technology Major Project(J2017-VI-0017-089)

Corresponding Authors: YAO Zhihao, professor, Tel: (010)62332884, E-mail: zhihaoyao@ustb.edu.cn

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	LI Dayu
	YAO Zhihao
	ZHAO Jie
	DONG Jianxin
	GUO Jing
	ZHAO Yu

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https://www.ams.org.cn/EN/10.11900/0412.1961.2023.00188 OR https://www.ams.org.cn/EN/Y2025/V61/I6/826

Fig.1 SEM images showing the distribution character-istics of different γ' phases in heat treated FGH4720Li powder metallurgy (P/M) superalloy
(a) primary γ' phase
(b) secondary γ' phase
(c) tertiary γ' phase

Fig.2 EBSD images of FGH4720Li P/M superalloy with inverse pole figure color after stress rupture at 600 ^oC (a-c) and 650 ^oC (d-f) for 500 h (a, d), 1000 h (b, e), and 2000 h (c, f)

Fig.3 Evolutions of grain size in FGH4720Li P/M superalloy after stress rupture under different conditions

Fig.4 SEM images and particle size distributions (insets) of secondary γ' phase in FGH4720Li P/M superalloy after stress rupture at 600 ^oC (a-c) and 650 ^oC (d-f) for 500 h (a, d), 1000 h (b, e), and 2000 h (c, f)

Fig.5 High magnified SEM images of secondary γ' phase in FGH4720Li P/M superalloy after stress rupture at 600 ^oC (a-c) and 650 ^oC (d-f) for 500 h (a, d), 1000 h (b, e), and 2000 h (c, f)

Fig.6 SEM images of tertiary γ' phase in FGH4720Li P/M superalloy after stress rupture at 600 ^oC (a-c) and 650 ^oC (d-f) for 500 h (a, d), 1000 h (b, e), and 2000 h (c, f) (Circles in Figs.6c-f show the gourd shaped tertiary γ' phases)

Fig.7 Schematic showing the evolution of grain size and γ' phase morphology characteristics in FGH4720Li P/M superalloy during stress rupture

Fig.8 Bright-field TEM images of FGH4720Li P/M superalloy after stress rupture at 600 ^oC (a) and 650 ^oC (b) for 2000 h (ESF—extended stacking fault)

Fig.9 Tensile properties of FGH4720Li P/M superalloy at 650 ^oC after aging and stress rupture at different time
(a) yield strength (b) ultimate tensile strength

Table 1 Average volume fractions and sizes of the secondary and tertiary γ' phases under different stress rupture conditions

Table 2 Parameters for calculating yield strength^{[6,7,30,35,41]}

Fig.10 Comparisons of theoretical calculated and experimental yield strengths of FGH4720Li P/M superalloy after stress rupture at 650 ^oC for different time

1	Yang J J, Zhang C S, Li H J, et al. Effect of tension-torsion coupled loading on the mechanical properties and deformation mechanism of GH4169 superalloys [J]. Acta Metall. Sin., 2024, 60: 30 doi: 10.11900/0412.1961.2022.00142
	杨俊杰, 张昌盛, 李洪佳等. 拉伸-扭转复合加载对镍基高温合金GH4169力学性能与变形机理的影响 [J]. 金属学报, 2024, 60: 30 doi: 10.11900/0412.1961.2022.00142
2	Li F L, Bai Y R, Meng L C, et al. Impact of aging heat treatment on microstructure and mechanical properties of a newly developed GH4096 disk superalloy [J]. Mater. Charact., 2020, 161: 110175
3	Locq D, Caron P. On some advanced nickel-based superalloys for disk applications [J]. Aerosp. Lab, 2011, 3: 1
4	Azadi M, Marbout A, Safarloo S, et al. Effects of solutioning and ageing treatments on properties of Inconel-713C nickel-based superalloy under creep loading [J]. Mater. Sci. Eng., 2018, A711: 195
5	Jiang X W, Wang D, Xie G, et al. The effect of long-term thermal exposure on the microstructure and stress rupture property of a directionally solidified Ni-based superalloy [J]. Metall. Mater. Trans., 2014, 45A: 6016
6	Jackson M P, Reed R C. Heat treatment of UDIMET 720Li: The effect of microstructure on properties [J]. Mater. Sci. Eng., 1999, A259: 85
7	Tan L M, Li Y P, Deng W K, et al. Tensile properties of three newly developed Ni-base powder metallurgy superalloys [J]. J. Alloys Compd., 2019, 804: 322
8	Deng W K, Zhang D, Wu H Y, et al. Prediction of yield strength in a polycrystalline nickel base superalloy during interrupt cooling [J]. Scr. Mater., 2020, 183: 139
9	Yao Z H, Hou J, Chen Y, et al. Effect of micron-sized particles on the crack growth behavior of a Ni-based powder metallurgy superalloy [J]. Mater. Sci. Eng., 2022, A860: 144242
10	Radis R, Schaffer M, Albu M, et al. Multimodal size distributions of γ′ precipitates during continuous cooling of UDIMET 720 Li [J]. Acta Mater., 2009, 57: 5739
11	Wan Z P, Hu L X, Sun Y, et al. Effect of solution treatment on microstructure and tensile properties of a U720LI Ni-based superalloy [J]. Vacuum, 2018, 156: 248
12	Mao J, Chang K M, Yang W H, et al. Cooling precipitation and strengthening study in powder metallurgy superalloy U720LI [J]. Metall. Mater. Trans., 2001, 32A: 2441
13	Huang Z L, Xie X F, Gu Y, et al. Tensile properties of Ni-based GH4720Li superalloys with different microstructures at 650 ^oC [J]. Chin. J. Rare Met., 2021, 45: 1269
	黄子琳, 谢兴飞, 谷雨等. GH4720Li镍基合金显微组织对650 ℃拉伸性能影响 [J]. 稀有金属, 2021, 45: 1269
14	Yuan Y, Gu Y F, Cui C Y, et al. Creep mechanisms of U720Li disc superalloy at intermediate temperature [J]. Mater. Sci. Eng., 2011, A528: 5106
15	Terzi S, Couturier R, Guétaz L, et al. Modelling the plastic deformation during high-temperature creep of a powder-metallurgy coarse-grained superalloy [J]. Mater. Sci. Eng., 2008, A483-484: 598
16	Zhao G D, Zang X M, Jing Y, et al. Role of carbides on hot deformation behavior and dynamic recrystallization of hard-deformed superalloy U720Li [J]. Mater. Sci. Eng., 2021, A815: 141293
17	Wang T, Li Z, Fu S H, et al. Hot deformation behavior and microstructure of U720Li alloy [J]. Adv. Mater. Res., 2013, 709: 143
18	Pang H T, Reed P A S. Microstructure effects on high temperature fatigue crack initiation and short crack growth in turbine disc nickel-base superalloy Udimet 720Li [J]. Mater. Sci. Eng., 2007, A448: 67
19	Tucker A M, Henderson M B, Wilkinson A J, et al. High temperature fatigue crack growth in powder processed nickel based superalloy U720Li [J]. Mater. Sci. Technol., 2002, 18: 349
20	Liu C, Yao Z H, Jiang H, et al. The feasibility and process control of uniform equiaxed grains by hot deformation in GH4720Li alloy with millimeter-level coarse grains [J]. Acta Metall. Sin., 2021, 57: 1309 doi: 10.11900/0412.1961.2020.00415
	刘超, 姚志浩, 江河等. GH4720Li合金毫米级粗大晶粒热变形获得均匀等轴晶粒的可行性及工艺控制 [J]. 金属学报, 2021, 57: 1309
21	Liu C, Yao Z H, Guo J, et al. Microstructure evolution behavior of powder superalloy FGH4720Li at near service temperature [J]. Acta Metall. Sin., 2021, 57: 1549 doi: 10.11900/0412.1961.2021.00140
	刘超, 姚志浩, 郭婧等. 粉末高温合金FGH4720Li在近服役温度下的组织演变规律 [J]. 金属学报, 2021, 57: 1549
22	Li M Z, Coakley J, Isheim D, et al. Influence of the initial cooling rate from γ′ supersolvus temperatures on microstructure and phase compositions in a nickel superalloy [J]. J. Alloys Compd., 2018, 732: 765
23	Hu B F, Liu G Q, Wu K, et al. Morphological instability of γ′ phase in nickel-based powder metallurgy superalloys [J]. Acta Metall. Sin., 2012, 48: 257
	胡本芙, 刘国权, 吴凯等. 镍基粉末冶金高温合金中γ′相形态不稳定性研究 [J]. 金属学报, 2012, 48: 257 doi: 10.3724/SP.J.1037.2011.00731
24	Kong W W, Wang Y Q, Yuan C, et al. Microstructural evolution and stress rupture behaviour of a Ni-Based wrought superalloy during thermal exposure [J]. Mater. Sci. Eng., 2021, A822: 141659
25	Schulz F, Li H Y, Kitaguchi H, et al. Influence of tertiary gamma prime (γ′) size evolution on dwell fatigue crack growth behavior in CG RR1000 [J]. Metall. Mater. Trans., 2018, 49A: 3874
26	Raynor D, Silcock J M. Strengthening mechanisms in γ′ precipitating alloys [J]. Met. Sci. J., 1970, 4: 121
27	Dang C X, Zhang P, Li J, et al. The role of <112> {111} slip in the initial plastic deformation of Ni-base superalloys at room temperature [J]. Mater. Charact., 2020, 170: 110648
28	Zhang P, Yuan Y, Li B, et al. Tensile deformation behavior of a new Ni-base superalloy at room temperature [J]. Mater. Sci. Eng., 2016, A655: 152
29	Goodfellow A J. Strengthening mechanisms in polycrystalline nickel-based superalloys [J]. Mater. Sci. Technol., 2018, 34: 1793
30	Kozar R W, Suzuki A, Milligan W W, et al. Strengthening mechanisms in polycrystalline multimodal nickel-base superalloys [J]. Metall. Mater. Trans., 2019, 40A: 1588
31	Nembach E, Neite G. Precipitation hardening of superalloys by ordered γ′-particles [J]. Prog. Mater. Sci., 1985, 29: 177
32	Zhao C L, Wang Q, Tang Y, et al. Microstructure and property stability of powder metallurgy nickel-based U720Li superalloy during long-term aging [J]. Rare Met. Mater. Eng., 2022, 51: 2356
33	Yao Z H, Dong J X, Chen X, et al. Gamma prime phase evolution during long-time exposure for GH738 superalloy [J]. Trans. Mater. Heat Treat., 2013, 34(1): 31
	姚志浩, 董建新, 陈旭等. GH738高温合金长期时效过程中γ′相演变规律 [J]. 材料热处理学报, 2013, 34(1): 31
34	Torster F, Baumeister G, Albrecht J, et al. Influence of grain size and heat treatment on the microstructure and mechanical properties of the nickel-base superalloy U 720 LI [J]. Mater. Sci. Eng., 1997, A234: 189
35	Xu Y L, Jin Q M, Xiao X S, et al. Strengthening mechanisms of carbon in modified nickel-based superalloy Nimonic 80A [J]. Mater. Sci. Eng., 2011, A528: 4600
36	Huang H L, Liu G Q, Wang H, et al. Effect of cooling rate and resulting microstructure on tensile properties and deformation mechanisms of an advanced PM nickel-based superalloy [J]. J. Alloys Compd., 2019, 805: 1254
37	Osada T, Nagashima N, Gu Y, et al. Factors contributing to the strength of a polycrystalline nickel-cobalt base superalloy [J]. Scr. Mater., 2011, 64: 892
38	Galindo-Nava E I, Connor L D, Rae C M F. On the prediction of the yield stress of unimodal and multimodal γ′ nickel-base superalloys [J]. Acta Mater., 2015, 98: 377
39	Gerold V, Haberkorn H. On the critical resolved shear stress of solid solutions containing coherent precipitates [J]. Phys. Status Solidi, 1966, 16B: 675
40	Ahmadi M R, Povoden-Karadeniz E, Whitmore L, et al. Yield strength prediction in Ni-base alloy 718Plus based on thermo-kinetic precipitation simulation [J]. Mater. Sci. Eng., 2014, A608: 114
41	Kocks U F, Mecking H. Physics and phenomenology of strain hardening: The FCC case [J]. Prog. Mater. Sci., 2003, 48: 171
42	Zhang H K, Li Y, Ma T F, et al. Tailoring of nanoscale γ′ precipitates and unveiling their strengthening mechanisms in multimodal nickel-based superalloy GH4720Li [J]. Mater. Charact., 2022, 188: 111918
43	Labusch R. A statistical theory of solid solution hardening [J]. Phys. Status Solidi, 1970, 41B: 659
44	Gypen L A, Deruyttere A. Multi-component solid solution hardening: part 2 Agreement with experimental results [J]. J. Mater. Sci., 1977, 12: 1034
45	Reppich B, Schepp P, Wehner G. Some new aspects concerning particle hardening mechanisms in γ′ precipitating nickel-base alloys—II. Experiments [J]. Acta Metall., 1982, 30: 95

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