Incipient melting of IN939 superalloy was investigated during solution annealing. In addition, the effect of this phenomenon was studied on hot workability of the alloy. The incipient melting was detected to be within the temperature range 1150–1160°C, which has been reported to be the standard temperature range of solution annealing of this material. The local melted regions were enriched in Zr, Nb and B elements, which appeared in the form of three different phases. The results also showed that even small amounts of local melted regions impair hot workability of the alloy. The use of long time solution annealing at 1150°C or a two-step solution heat treatment has been recommended to delay the incipient melting of the alloy. These treatments enhance hot workability of the alloy.
SimsCT, StoloffNS, HagelWC: ‘Superalloys II’; 1987, New York, John Wiley and Sons.
2.
DonachieMJ, DonachieSJ: ‘Superalloys: a technical guide’, 2nd edn; 2002, Materials Park, OH, ASM International.
3.
DavisJR: ‘Heat resistant materials’; 1997, Materials Park, OH, ASM International.
4.
ReedRC: ‘The superalloys: fundamentals and applications’; 2006, Cambridge, Cambridge University Press.
5.
GibbonsTB, SticklerR:‘IN939 metallurgy, properties and performances’in ‘High temperature alloys for gas turbines’(, BrunetaudR, et al..), 369–394; 1982, Liege, D. Reidel Publishing Company.
6.
CutlerCP, ShawSWK: ‘The interrelationship of γ′ size, grain size and mechanical properties in IN939, a cast nickel-base superalloy’, Proc. 5th Int. Conf. on ‘Strength of metals and alloys’, Aachen, Germany, August 1979, Pergamon,1357–1362.
JovanovicMT, MiskovicZ, LukicB: ‘Microstructure and stress-rupture life of polycrystal, directionally solidified and single crystal casting on nickel based IN939 superalloy’,Mater. Charact., 1998, 40, 261–268.
9.
MiskovicZ, JovanovicM, GligicM, LukicB: ‘Microstructural investigation of IN 939 superalloy’,Vacuum, 1992, 43, (5), 709–711.
10.
DelargyKM, SmithGDW: ‘Phase composition and phase stability of a high-chromium nickel-based superalloy IN939’,Metall. Trans. A, 1983, 14A, 1771–1783.
11.
DelargyKM, ShawSWK, SmithGDW: ‘Effects of heat treatment on mechanical properties of high-chromium nickel-base superalloy IN939’,Mater. Sci. Technol., 1986, 2, 1031–1037.
12.
HatalaRW, SchirraJJ:‘Development of a damage tolerant heat treatment for cast+hip Incoloy 939’in ‘Superalloys 1996’(, KissingerR D, et al..), 137–143; 1996, Warrendale, PA, TMS.
13.
ShawSWK:‘Response of IN939 to process variations, Superalloys’in ‘Superalloys 1980’(, TienJ K, et al..), 275–284; 1980, Champion, PA, TMS.
14.
BalikciE, ErdenizD: ‘Multimodal precipitation in the superalloy IN738LC’,Metall. Mater. Trans. A, 2010, 41A, 1391–1398.
ErdenizD, BalikciE: ‘Precipitate formation and evolution in the superalloy IN738LC’,Rare Met. Mater. Eng., 2009, 38, (3), 142–146.
17.
LiP, LiSS, HanYF: ‘Influence of solution heat treatment on microstructure and stress rupture properties of a Ni3Al base single crystal superalloy IC6SX’,Intermetallics, 2011, 19, (2), 182–186.
18.
GibbonsTB: ‘Superalloys in modern power generation applications’,Mater. Sci. Technol., 2009, 25, (2), 129–135.
19.
HegdeSR, KearseyRM, BeddoesJC: ‘Designing homogenization–solution heat treatments for single crystal superalloys’,Mater. Sci. Eng. A, 2010, A527, (21–22), 5528–5538.
20.
DupontJN, RobinoCV, MichaelJR, NotisMR, MarderAR: ‘Solidification of Nb-bearing superalloys. Part I: reaction sequences’,Metall. Mater. Trans. A, 1998, 29A, 2785–2796.
21.
LongZ, LiuX, YangW, ChangKM, BarberoE: ‘Thermodynamic assessment of liquid composition change during solidification and its effect on freckle formation in superalloys’,Mater. Sci. Eng. A, 2004, A386, 254–261.
22.
JablonskiPD, CowenCJ: ‘Homogenizing a nickel-based superalloy: thermodynamic and kinetic simulation and experimental results’,Metall. Mater. Trans. B, 2009, 40B, 182–186.
23.
MiaoZJ, ShanAD, LuJ, SongHW: ‘Segregation and diffusion characterisation in two-stage homogenisation of conventional superalloy’,Mater. Sci. Technol., 2011, 27, (10), 1551–1557.
24.
WarnkenN, MaD, DrevermannA, ReedRC, FriesSG, SteinbachI: ‘Phase-field modelling of as-cast microstructure evolution in nickel-based superalloys’,Acta Mater., 2009, 57, 5862–5875.
25.
YuL, ZhaoY, YangS, SunW, GuoS, SunX, HuZ: ‘As-cast microstructure and solidification behavior of a high Al- and Nb-containing superalloy’,J. Mater. Sci., 2010, 45, 3448–3456.
26.
SponsellerDL:‘Differential thermal analysis of nickel-base superalloys’in ‘Superalloys 1996’(, KissingerR D, et al..), 259–270; 1996, Warrendale, PA, TMS.
27.
ChapmanLA: ‘Application of high temperature DSC technique to nickel based superalloys’,J. Mater. Sci., 2004, 39, 7229–7236.
28.
D'SouzaN, DongHB: ‘Determination of transition temperatures during freezing and melting of interdendritic phases in Ni based superalloys’,Mater. Sci. Technol., 2011, 27, (1), 325–331.
29.
FormentiA, EliassonA, MitchellA, FredrikssonH: ‘Solidification sequence and carbide precipitation in Ni-base superalloys IN718, IN625 and IN939’,High Temp. Mater. Process., 2005, 24, (4), 239–258.
30.
CzirakiA, FogarrasiB, Van TendelooG, LamparterP, TegzeM, BakonyiI: ‘Electron microscopy and X-ray diffraction studies of rapidly quenched Zr–Ni and Hf–Ni ribbons with about 90 at Ni’,J. Alloy Compd, 1994, 210, 135–141.
31.
XuY: ‘Experimental study of the structure of Ni–Zr metallic glasses’, PhD thesis, McGill University, Montreal, Que., Canada, 1993.
MiaoZJ, ShanAD, LuJ, SongHW: ‘Microstructure and solidification behaviour characterisation of phosphorus and boron doped IN718 superalloy’,Mater. Sci. Technol., 2012, 28, (3), 334–341.
35.
LilingS, QiW, ZhiyaZ, ZhuangqiH: ‘Effect of trace element B on microstructure of directionally solidified Co-base superalloy DZX40M’,Acta Metall. Sin., 1994, 7, (1), 23–26.
36.
OjoOA, ChaturvediMC: ‘Liquation microfissuring in the weld heat-affected zone of an overaged precipitation-hardened nickel-base superalloy’,Metall. Mater. Trans. A, 2007, 38A, 356–369.
37.
MiaoZJ, ShanAD, WuYB, LuJ, HuY, LiuJL, SongHW: ‘Effects of P and B addition on as-cast microstructure and homogenization parameter of Inconel 718 alloy’,Trans. Nonferr. Met. Soc. China, 2012, 22, 318–323.
38.
ZhangJ, SingerRF: ‘Effect of Zr and B on castability of Ni-based superalloy IN792’,Metall. Mater. Trans. A, 2004, 35A, 1337–1342.
