1. Institute of Powder Metallurgy and Advanced Ceramics, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China 2. Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095, China
Cite this article:
TIAN Tian, HAO Zhibo, JIA Chonglin, GE Changchun. Microstructure and Properties of a New Third Generation Powder Metallurgy Superalloy FGH100L. Acta Metall Sin, 2019, 55(10): 1260-1272.
Spray forming (SF) is a novel rapid solidification technique. Compared with traditional cast & wrought and powder metallurgy technique, it has the advantages of less segregation and shorter process. In this work, a new third generation powder metallurgy (PM) superalloy FGH100L was prepared by SF+hot isostatic pressing (HIP)+isothermal forging (IF)+heat treatment (HT) process. The effects of solution heat treatment temperatures and preparation process on the microstructure and mechanical properties of FGH100L alloy were studied. The results show that the microstructure of SF+HIP+IF state FGH100L alloy is very sensitive to changes of solution temperature. With the increase of the solution temperature (1110~1170 ℃), the grain size of the alloy grew, and the size of the γ' strengthened phase first increased and then decreased. Its hardness, tensile strength and plasticity at room temperature/high temperature all show a trend of increasing followed by decreasing. The quantitative equilibrium of three sizes of γ' phase in the alloy is more reasonable, the microstructure of the alloy is the best, and the hardness and room temperature/high temperature tensile properties of alloy have the highest parameter values at 1130 ℃. At the same temperature, the grain size of FGH100L alloy increased first and then decreased under different processing conditions of SF, SF+HIP+HT and SF+HIP+IF+HT. The morphology of grains changed from subspherical to polygonal to subspherical. Alloy grain size increases, and the grain boundary bending degree decreases in the process of SF+HIP+HT. Due to SF+HIP+IF+HT process, the alloy recrystallizes, refines the grain, and presents chain-like structure, forming curved grain boundary and having higher yield strength. Under SF+HIP+HT and SF+HIP+IF+HT processes, the tensile fracture of the alloy at room temperature changed from intergranular brittle fracture to transgranular and intergranular mixed fracture, and the tensile fracture at high temperature was intergranular fracture.
Table 1 Density and relative density of FGH100L alloy under different process states
Fig.1 DSC curve of FGH100L alloy
Fig.2 Relationship between precipitation phase and temperature in FGH100L alloy
Fig.3 OM images of SF+HIP+IF state FGH100L alloy after solution heat treatment at 1110 ℃ (a), 1130 ℃ (b), 1150 ℃ (c), 1170 ℃ (d), and EBSD image at 1130 ℃ (e) and statistical map of local misorientation at 1130 ℃ (f) (Inset in Fig.3d shows the enlarged view, arrow shows grain boundary bent and bulged)
Fig.4 Low (a, c, e, g) and high (b, d, f, h) magnified SEM images of precipitation phases of SF+HIP+IF state FGH100L alloy after solution heat treatment at 1110 ℃ (a, b), 1130 ℃ (c, d), 1150 ℃ (e, f) and 1170 ℃ (g, h)
Fig.5 OM images of FGH100L alloy under the processing of SF (a), SF+HIP+HT (b), SF+HIP+IF+HT (c, d) (Insets show the enlarnged views)
Fig.6 SEM images of precipitates of FGH100L alloy under the processing of SF (a, c, d), SF+HIP+HT (e, g, h), SF+HIP+IF+HT (i, k, l) and corresponding EDS analyses (b, f, j) (Insets show the enlarged views)
Fig.7 Relationships between Brinell hardness and solution temperature of FGH100L alloy under different process states
Processes
Solution temperature / ℃
Rp0.2 / MPa
Rm / MPa
δ / %
SF
-
911
1078
27.5
SF+HIP+HT
1130
1100
1550
20.0
SF+HIP+IF+HT
1110
1180
1580
16.5
1130
1210
1620
21.5
1150
1100
1560
18.5
1170
1090
1540
15.0
AA-LSHR[26,27]
1130
1045
1538
15.0
Table 2 Room temperature tensile properties of FGH100L alloy at different processes and solution temperatures
Processes
Solution temperature / ℃
Rp0.2 / MPa
Rm / MPa
δ / %
SF+HIP+HT
1130
1050
1310
11.5
SF+HIP+IF+HT
1110
1000
1250
8.0
1130
1140
1380
16.5
1150
1139
1360
10.0
1170
1130
1320
12.5
AA-LSHR[26,27]
1130
1137.7
1316.9
8.0
Table 3 High temperature (705 ℃) tensile properties of FGH100L alloy at different processes and solution temperatures
Fig.8 SEM images of tensile fractures of FGH100L superalloy under different hot processes of SF at 20 ℃ (a, b), SF+HIP+HT at 20 ℃ (c~f), SF+HIP+IF+HT at 20 ℃ (g~j) and SF+HIP+IF+HT at 705 ℃ (k~n)
[1]
Gabb T P, Telesman J, Kantzos P T ,et al. Characterization of the temperature capabilities of advanced disk alloy ME3 [R]. Washington: National Aeronautics and Space Administration, 2002
[2]
Hu B F, Liu G Q, Jia C C ,et al. Development in new type high-performance P/M superalloys [J]. J. Mater. Eng., 2007, 35(2): 49
Raisson G. Evolution of PM nickel base superalloy processes and products [J]. Powder Metall., 2008, 51(1): 10
[5]
Crozet C, Devaux A, Forestier R ,et al. Effect of ingot size on microstructure and properties of the new advanced AD730TM superalloy [A]. Proceedings of the 13th International Symposium of Superalloys [C]. New York: TMS, 2016: 437
[6]
Henein H, Uhlenwinkel V, Fritsching U. Metal Sprays and Spray Deposition [M]. Cham: Springer, 2017: 497
[7]
Bricknell R H. The structure and properties of a nickel-base superalloy produced by osprey atomization-deposition [J]. Metall. Trans., 1986, 17A: 583
[8]
Fiedler H C, Sawyer T F, Kopp R W ,et al. The spray forming of superalloys [J]. JOM, 1987, 39(8): 28
[9]
Chang K M, Fiedler H C. Spray-formed high-strength superalloys [A]. Proceedings of the Sixth International Symposium on Superalloys [C]. New York: TMS, 1988: 485
[10]
Moran A L, Palko W A. Spray forming alloy 625 marine piping [J]. JOM, 1988, 40(12): 12
[11]
Kennedy R L, Davis R M, Vaccaro F P. An evaluation of spray formed alloy 718 [A]. Superalloy718: Metallurgy and Applications [C]. Warrendale: TMS, 1989: 97
[12]
Benz M G, Sawyer T F, Carter W T ,et al. Nitrogen in spray formed superalloys [J]. Powder Metall., 1994, 37: 213
[13]
Grant P S. Solidification in spray forming [J]. Metall. Mater. Trans., 2007, 38A: 1520
[14]
Mi J, Grant P S, Fritsching U ,et al. Multiphysics modelling of the spray forming process [J]. Mater. Sci. Eng., 2008, A477: 2
[15]
Zhang G Q, Mi G F, Li Z ,et al. Spray formed nickel based superalloys using argon as atomization gas [J]. Chin J. Nonferrous Met., 1999, 9suppl.): 90
Mi G F, Liu Y L, Tian S F ,et al. Microstructure and mechanical properties of spray deposited Ni-based superalloys [J]. J.Univ Wuhan. Technol.-Mater. Sci. Ed., 2009, 24: 796
[19]
Sun J F, Shen J, Cao F Y, alat. Tensile frecture behaviors of spray formed superalloy [J]. Nonferrous Met., 2002, 54(2): 25
Kang F W, Cao F Y, Zhang X M ,et al. Microstructure and mechanical properties of a spray-formed superalloy [J]. Acta Metall. Sin. (Engl. Lett.), 2014, 27: 1063
[21]
Luo G M, Fan J F, Shan A D. Microstructure analysis of spray-formed superalloy FGH4096 [J]. Baosteel Technol., 2008, (2): 54
Jia C L, Ge C C, Yan Q Z. Microstructure evolution and mechanical properties of disk superalloy under multiplex heat treatment [J]. Mater. Sci. Eng., 2016, A659: 287
[24]
Jia C L, Ge C C, Yan Q Z. Innovative technologies for powder metallurgy-based disk superalloys: Progress and proposal [J]. Chin. Phys., 2016, 25B: 026103
[25]
Wu H H, Wang C W, Zhong J H ,et al. Dispersion effect of graphene composite particles by spray forming [J]. Spec. Casting Nonferrous Alloy, 2019, 39: 75
Gabb T P, Kantzos P T. Thermal and mechanical property characterization of the advanced disk alloy LSHR [R]. Cleveland: NASA Glenn Research Center, 2005
[27]
Jou H J. Microstructure modeling of third generation disk alloys [R]. Cleveland: NASA, 2010
[28]
Wang X H, Zheng L, Zhang M C ,et al. Microstructural characteristics and thermodynamic calculation on precipitated phases of GH4133B alloy [J]. Rare Met. Mater. Eng., 2011, 40: 1005
Tian G F, Wang Y, Yang J, et al. Thermodynamic calculation on equilibrium precipitated phases in P/M nickel-base superalloy [J]. Powder Metall. Technol., 2012, 30: 243
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
Jia C L, Zhang F L, Li Y. Investigation on microstructure evolution of a new disk superalloy under different hot process [J]. Met. Powder Rep., 2018, 73: 319
[34]
Hu B F, Liu G Q, Wu K ,et al. Morphological changes behavior of fan-type structures of γ' precipitates in nickel-based powder metallurgy superalloys [J]. Acta Metall. Sin., 2012, 48: 830
Hu B F, Chen H M, Song D ,et al. The effect of pre-heating on carbide precipatites in FGH95 superalloy powders prepared by PREP [J]. Acta Metall. Sin., 2003, 39: 470
Qin X Z, Guo J T, Yuan C ,et al. Decomposition of primary MC carbide and its effects on the fracture behaviors of a cast Ni-base superalloy [J]. Mater. Sci. Eng., 2008, A485: 74
[37]
Zhang Y, Zhang Y W, Zhang N, et al. Heat treatment processes and microstructure and properties research on P/M superalloy FGH97 [J]. J. Aeron. Mater., 2008, 28(6): 5
Wu K, Liu G Q, Hu B F ,et al. Effect of solution cooling rate and pre-heat treatment on the microstructure and microhardness of a novel type nickel-based P/M superalloy [J]. Rare Met. Mater. Eng., 2012, 41: 685
Yang W P, Hu B F, Liu G Q, et al. Formation mechanism of serrated grain boundary caused by different morphologies of γ' phases in a high-performance nickel-based powder metallurgy superalloy [J]. J. Mater. Eng., 2015, 43(6): 7
Ponge D, Gottstein G. Necklace formation during dynamic recrystallization: Mechanisms and impact on flow behavior [J]. Acta Mater., 1998, 46: 69
[41]
Zhong X T, Wang L, Liu F. Study on formation mechanism of necklace structure in discontinuous dynamic recrystallization of Incoloy 028 [J]. Acta Metall. Sin., 2018, 54: 969
Wu K, Liu G Q, Hu B F, et al. Effect of solution heat treatment on the microstructure and properties of a novel nickel-based P/M superalloy FGH98 I [J]. Rare Met. Mater. Eng., 2011, 40: 1966
