In this research, the effect of two different per centages of silicon, i.e. 0.08 and 0.3 wt-%, on microstructure and stress rupture life of a Ni-based superalloy was investigated. The results showed that the fraction of eutectic increased from 1.86 to 3.55% with increasing Si content and a higher fraction of eutectic was found on grain boundaries in high Si-bearing alloy. Upon stress rupture at 975°C/225 MPa, cracking initiates and propagates along Laves phases in 0.3 wt-% Si alloy, causing shorter lifetime comparing to that of 0.08 wt-% Si. The microscopic examination uncovered that Si prefers to segregate towards liquid and γ phase, which can explain different rupture lifetimes of two groups of Si-bearing alloys.
PollockTMTinSJ.Nickel-based superalloys for advanced turbine engines: chemistry, microstructure and properties. Journal of propulsion and power. 2006; 22(2):361–374.
2.
SimsCTHagelWC.The superalloys II. New York: John Wiley & Sons; 1987.
3.
ReedRC.The superalloys: fundamentals and applications. Cambridge: Cambridge University Press; 2006.
4.
ChengKYJoCYJinTPrecipitation behavior of μ phase and creep rupture in single crystal superalloy CMSX-4. J Alloys Compd. 2011; 509(25):7078–7086.
5.
ChenQZJonesNKnowlesDM.The microstructures of base/modified RR2072 SX superalloys and their effects on creep properties at elevated temperatures. Acta Mater. 2002; 50(5):1095–1112.
6.
ShirvaniKSaremiMNishikataAThe effect of silicon on cyclic oxidation behavior of aluminide coatings on superalloy IN-738LC. Mater Sci Forum. 2004; 461:335–342.
7.
MinerRVLowellCE. Effects of silicon additions on oxidation and mechanical behavior of the nickel-base superalloy B-1900. 1975;NASA TN D-7989.
8.
MinerRV.Effects of silicon on the oxidation, hot-corrosion, and mechanical behavior of two cast nickel-base superalloys. Metall Trans A. 1977; 8(12):1949–1954.
9.
YunDWSeoSMJeongHWThe effects of the minor alloying elements Al, Si and Mn on the cyclic oxidation of Ni–Cr–W–Mo alloys. Corros Sci. 2014; 83:176–188.
XuZFJiangLDongJSThe effect of silicon on precipitation and decomposition behaviors of M6C carbide in a Ni–Mo–Cr superalloy. J Alloys Compd. 2015; 620:197–203.
12.
WangYSGuanXMYeHQEffect of silicon on grain boundary carbide precipitation and properties of a cobalt-free wrought nickel-base superalloy. Superalloys. 1980; 20:63–70.
13.
YangJXZhengQSunXFFormation of μ phase during thermal exposure and its effect on the properties of K465 superalloy. Scripta Mater. 2006; 55(4):331–334.
14.
YangJZhengQSunXRelative stability of carbides and their effects on the properties of K465 superalloy. Mater Sci Eng A. 2006; 429(1–2):341–347.
15.
YuanXFSongJXZhengYRAbnormal stress rupture property in K465 superalloy caused by microstructural degradation at 975°C/225 MPa. J Alloys Compd. 2016; 662:583–592.
16.
YangJXZhengQSunXFTopologically close-packed phase precipitation in a nickel-base superalloy during thermal exposure. Mater Sci Eng A. 2007; 465(1-2):100–108.
17.
PearsonWB.The crystal chemistry and physics of metals and alloys. Wiley-Inter-Science; 1972. 135.
Yeh ACKawagishiKHaradaHDevelopment of Si-bearing 4th generation Ni-base single crystal superalloys. Carbon N Y. 2008; 20(34):13.
20.
RadhakrishnaCHRaoKP.The formation and control of laves phase in superalloy 718 welds. J Mater Sci. 1997; 32(8):1977–1984.
21.
RadhakrishnaCHRaoKPSrinivasS.Laves phase in superalloy 718 weld metals. J Mater Sci Lett. 1995; 14(24):1810–1812.
22.
FurilloFTDavidsonJMTienJKThe effects of grain boundary carbides on the creep and back stress of a nickel-base superalloy. Mater Sci Eng. 1979; 39(2):267–273.
23.
BaeJSLeeJHKimSSFormation of MC-γ/γ’eutectic fibers and their effect on stress rupture behavior in D/S Mar-M247LC superalloy. Scripta Mater. 2001; 45(5):503–508.
24.
FernandezRLecomteJCKattamisTZ.Effect of solidification parameters on the growth geometry of MC carbide in IN-100 dendritic monocrystals. Metall Trans A. 1978; 9(10):1381–1386.
25.
LiuLSommerFFuHZ.Effect of solidification conditions on MC carbides in a nickel-base superalloy IN 738 LC. Scripta Mater. 1994; 30(5):587–591.
26.
ChenJLeeJHJoCYMC carbide formation in directionally solidified MAR-M247 LC superalloy. Mater Sci Eng A. 1998; 247(1–2):113–125.
27.
ZhaoKMaYHLouLH.Improvement of creep rupture strength of a liquid metal cooling directionally solidified nickel-base superalloy by carbides. J Alloys Compd. 2009; 475(1–2):648–651.
28.
LiuLRJinTZhaoNRFormation of carbides and their effects on stress rupture of a Ni-base single crystal superalloy. Mater Sci Eng A. 2003; 361(1–2):191–197.
29.
ChenQZJonesCNKnowlesDM.The grain boundary microstructures of the base and modified RR 2072 bicrystal superalloys and their effects on the creep properties. Mat Sci Eng A. 2004; 385(1–2):402–418.
30.
ZhaoWWLinXLiuFCEffect of heat treatment on microstructure and mechanical properties of laser solid forming Inconel 718 superalloy. Chin J Lasers. 2009; 36(12):3220–3225.
31.
MingXLChenJTanHResearch on persistent fracture mechanism of laser forming repaired GH4169 superalloy. Chin J Lasers. 2015; 42:1–7.
32.
ZhangYLiZNiePEffect of cooling rate on the microstructure of laser-remelted INCONEL 718 coating. Metall Mater Trans A. 2013; 44(12):5513–5521.
33.
RadhakrishnaCRaoKP.Studies on creep/stress rupture behaviour of superalloy 718 weldments used in gas turbine applications. Mater High Temp. 1994; 12(4):323–327.
34.
DoiMMiyazakiTWakatsukiT.The effect of elastic interaction energy on the morphology of γ′ precipitates in nickel-based alloys. Mater Sci Eng. 1984; 67(2):247–253.
35.
FuchsGE.Solution heat treatment response of a third generation single crystal Ni-base superalloy. Mater Sci Eng A. 2001; 300(1-2):52–60.
36.
FuchsGE.Improvement of creep strength of a third generation, single-crystal Ni-base superalloy by solution heat treatment. J Mater Eng Perform. 2002; 11(1):19–25.
37.
FenchengLXinLWeiweiZEffects of solution treatment temperature on microstructures and properties of laser solid forming GH4169 superalloy. Rare Metal Mater Eng. 2010; 39(9):1519–1524.
38.
BlackwellPL.The mechanical and microstructural characteristics of laser-deposited IN718. J Mater Process Technol. 2005; 170(1-2):240–246.
39.
ZhaoXMChenJLinXStudy on microstructure and mechanical properties of laser rapid forming Inconel 718. Mater Sci Eng A. 2008; 478(1-2):119–124.
40.
QiHAzerMRitterA.Studies of standard heat treatment effects on microstructure and mechanical properties of laser net shape manufactured Inconel 718. Metall Mater Trans A. 2009; 40(10):2410–2422.
41.
SongKYuKLinXMicrostructure and mechanical properties of heat treatment laser solid forming superalloy Inconel 718. Acta Metall Sin. 2015; 51(8):935–942.
