The present study investigated the sintering behaviour of Nb–16Si–25Ti–8Hf–2Cr–2Al alloy powders. The alloy powders were produced using ahydrogenation–dehydrogenation method and featured an irregular morphology. Powders sintered at 1500°C and 1600°C exhibited pores in their microstructures, while powders sintered at 1700°C for 4 h were fully densified and poreless. The cast ingot and powders were composed of three phases: Nbss, Nb5Si3, and Nb3Si. However, the Nb3Si phase was not observed, while HfO2 oxides formed in the sintered compact. The hafnium and oxygen reacted to form an HfO2 oxide during the high-temperature sintering process. From the result of the thermodynamic calculation, Hf oxide formed after sintering because Hf has the highest driving force for oxidation among the elements constituting the alloy.
BewlayBPJacksonMRSubramanianPRA review of very-high-temperature Nb-silicide-based composites. Metall Mater Trans A. 2003; 34:2043–2052. doi: 10.1007/s11661-003-0269-8
2.
SivakumarRMordikeBL.High temperature coatings for gas turbine blades: a review. Surf Coat Technol. 1989; 37:139–160. doi: 10.1016/0257-8972(89)90099-6
3.
LawCKMakinoALuTF.On the off-stoichiometric peaking of adiabatic flame temperature. Combust Flame. 1989; 145:808–819. doi: 10.1016/j.combustflame.2006.01.009
JiaoHJonesIPAindowM.Microstructures and mechanical properties of Nb–Ti–C alloys. Mater Sci Eng A. 2008; 485:359–366. doi: 10.1016/j.msea.2007.08.035
6.
BewlayBPJacksonMRLipsittHA.The balance of mechanical and environmental properties of a multielement niobium-niobium silicide-based in situ composite. Metall Mater Trans A. 1996; 27:3801–3808. doi: 10.1007/BF02595629
7.
SubramanianPRMendirattaMGDimidukDM.Microstructures and mechanical behavior of Nb-Ti base beta + silicide alloys. MRS Proc. 1993; 322:491. doi: 10.1557/PROC-322-491
8.
MendirattaMGLewandowskJJDimidukDM.Strength and ductile-phase toughening in the two-phase Nb/Nb5Si3 alloys. Metall Trans A. 1991; 22: 1573–1583. doi: 10.1007/BF02667370
9.
ChanKSDavidsonDL.Improving the fracture toughness of constituent phases and Nb-based in-situ composites by a computational alloy design approach. Metall Mater Trans A. 2003; 34:1833–1849. doi: 10.1007/s11661-003-0149-2
10.
JacksonMRRoweRGSkellyDW.Oxidation of some intermetallic compounds and intermetallic matrix composites. MRS Proc. 1994; 364:1339. doi: 10.1557/PROC-364-1339
11.
ZhengPShaJBLiuDMEffect of Hf on high-temperature strength and room-temperature ductility of Nb–15W–0.5Si–2B alloy. Mater Sci Eng A. 2008; 483-484:656–659. doi: 10.1016/j.msea.2006.09.135
12.
ChanKS.Cyclic oxidation response of multiphase niobium-based alloys. Metall Mater Trans A. 2004; 35: 589–597. doi: 10.1007/s11661-004-0370-7
13.
ZhangPGuoX.Effect of Al content on the structure and oxidation resistance of Y and Al modified silicide coatings prepared. Corros Sci. 2013; 71:10–19. doi: 10.1016/j.corsci.2013.01.010
14.
SubramanianPRMendirattaMGDimidukDM.The development of Nb-based advanced intermetallic alloys for structural applications. JOM. 1996; 48:33–38. doi: 10.1007/BF03221360
ChanKS.Modeling creep behavior of niobium silicide in-situ composites. Mater Sci Eng A. 2002; 337:59–66. doi: 10.1016/S0921-5093(02)00011-4
17.
GuoYHeJLiZTuning microstructures and improving oxidation resistance of Nb-Si based alloys via electron beam surface melting. Corros Sci. 2020; 163:108281. doi: 10.1016/j.corsci.2019.108281
18.
ChenZYanYW.Influence of sintering temperature on microstructures of Nb/Nb5Si3 in situ composites synthesized by spark plasma sintering. JALCOM. 2006; 413:73–76.
19.
LiuWFuYShaJ.Microstructure and mechanical properties of Nb–Si alloys fabricated by spark plasma sintering. Prog Nat Sci: Mater Intl. 2013; 23:55–63. doi: 10.1016/j.pnsc.2013.01.009
20.
LeeWHParkKBYiKWSynthesis of spherical V-Nb-Mo-Ta-W high-entropy alloy powder using hydrogen embrittlement and spheroidization by thermal plasma. Metals (Basel). 2019; 9:1296. doi: 10.3390/met9121296
21.
NaTWParkKBLeeSYPreparation of spherical TaNbHfZrTi high-entropy alloy powders by a hydrogenation–dehydrogenation reaction and thermal plasma treatment. J Alloy Compd. 2020; 817:152757. doi: 10.1016/j.jallcom.2019.152757
22.
ParkKBChoiJHNaTWOxygen reduction behavior of HDH TiH2 powder during dehydrogenation reaction. Metals (Basel). 2019; 9:1154. doi: 10.3390/met9111154
23.
LeeSYLeeWHParkKBSynthesis of Nb-Mo-Si based in situ composite powder by a hydrogenation-dehydrogenation reaction. Mater Lett. 2019; 248:32–35. doi: 10.1016/j.matlet.2019.03.134
24.
LeeSYParkKBKangJWSpark plasma sintering behavior of Nb-Mo-Si alloy powders fabricated by hydrogenation-dehydrogenation. Mater. 2019; 12:3549. doi: 10.3390/ma12213549
