scholarly journals Investigation on Optimal Ta/Cr Ratio of a Single Crystal Ni-Base Superalloy in View of the Isothermal Oxidation Behavior

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1421
Author(s):  
Jianxiu Chang ◽  
Wenhao Feng ◽  
Wenwen Zhao ◽  
Hongmin Jia ◽  
Yanming Liu ◽  
...  
Keyword(s):  
Single Crystal ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Nitride Layer ◽  
Oxidation Products ◽  
Competitive Growth ◽  
X Ray Diffraction ◽  
Al2o3 Layer ◽  
Oxidation Performance

The relative content of strengthening element tantalum (Ta) and oxidation-resistant element chromium (Cr) is an essential value for superalloys to obtain an excellent combination of oxidation resistance and mechanical properties. In the present paper, the isothermal oxidation behavior of several single crystal Ni-base superalloys with different Ta/Cr (wt. %, similarly hereinafter) ratios at 1000 °C in static air has been systematically investigated to explore the optimal Ta/Cr for excellent oxidation resistance. A detailed microstructure study using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and an electro-probe microanalyzer (EPMA) was performed to reveal the oxidation products and mechanisms. For all alloys, a three-layer structured scale consisting of an outer (Cr, Al, Ti, Ni, Ta)-O layer, an inner Al2O3 layer and an inner nitride layer was formed. As Ta/Cr increased, the amounts of Ta-containing products, cracks, holes and inner nitride increased. Meanwhile, the completeness of the Al2O3 layer got worse. It was shown that if Ta/Cr ≤ 0.5, Ta increased the growth rate of Cr2O3 via the doping effect induced by Ta cations. If Ta/Cr > 0.5, Ta reduced the completeness of Cr2O3 through competitive growth of Ta2O5 and Cr2O3. A good oxidation performance can be expected with the value Ta/Cr ≤ 0.5.

Improvement of Oxidation Resistance of A NiAl Eutectic Alloy Doping with Dy

2010 ◽  
Vol 34-35 ◽  
pp. 1263-1268
Author(s):  
Guang Ye Zhang ◽  
Jin Lin Wang ◽  
You Ming Chen ◽  
Long Fei Liu ◽  
Yuan Jun Guo
Keyword(s):  
Oxidation Resistance ◽  
Eutectic Alloy ◽  
Transition Layer ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Al2o3 Layer

The isothermal oxidation behavior of NiAl-30.9Cr-3Mo-0.1Dy alloy has been investigated in the paper. The results reveal that Dy-addition significantly improves the oxidation resistance, which is attributed to the formation of continuously compact Al2O3 layer and rich-Cr transition layer on the surface of the tested alloy.

Phase Constitution and Oxidation Resistance of B2 (Ir, Co)Al

2002 ◽  
Vol 753 ◽  
Author(s):  
Hideki Hosoda ◽  
Hiroshi Noma ◽  
Kenji Wakashima
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Hot Forging ◽  
Isothermal Oxidation ◽  
Oxidation Products ◽  
Phase Constitution ◽  
Temperature Oxidation ◽  
Arc Melting ◽  
Oxidation Resistant ◽  
Ultrahigh Temperature

ABSTRACTB2 iridium aluminide (IrAl) is hopeful for use as an ultrahigh temperature oxidation resistant coating above 1600K. In this study, the effect of Co substitution for Ir on phase constitution, hardness and oxidation behavior was studied for IrAl alloys. Alloys of (Ir, Co)-50mol%Al with various Co contents were fabricated by Ar-arc melting followed by hot-forging at 1773K. Oxidation behavior was evaluated using thermogravimetry (TG) in Ar-67%O2 up to 1823K. XRD and SEM were also carried out for alloy characterization. It was found that a continuous B2 solid solution (Ir,Co)Al is formed between IrAl and CoAl. Depending on the Co concentration, the oxidation products identified after heating to 1873K in Ar-67%O2 were Ir, IrO2 and A2O3 and/or Co2AlO4. Thin and continuous Al2O3 layers were observed after isothermal oxidation at 1673K when Co content is more than 20mol%Co. In this case, the weight change by isothermal oxidation at 1673K becomes higher with decreasing Co content. The (Ir,Co)Al alloys containing 20–40mol%Co exhibit higher oxidation resistance than CoAl and IrAl, and thus oxidation resistance of CoAl is improved by Ir addition.

scholarly journals Effect of Y on the Oxidation Behavior of a Directionally Solidified Ni-based Single Crystal Superalloy

2020 ◽  
Author(s):  
Zihan Zhao ◽  
Kai Guan ◽  
Renjie Cui ◽  
Jianchao Qin ◽  
Zhaohui Huang
Keyword(s):  
Weight Gain ◽  
Single Crystal ◽  
Oxide Scale ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxidation Products ◽  
Single Crystal Superalloy ◽  
Directionally Solidified ◽  
Oxidation Weight Gain

Abstract The effect of Y addition on the oxidation behavior of a Ni-based directionally solidified single crystal superalloy was investigated. Isothermal oxidation test for the samples with different-level Y addition was conducted at 1100℃ in air. The Y content of the samples was demarcated by the actual pickup amount resulted from ICP-AES test. It was found that the addition of Y increased the oxide resistance by an adhesive double-layer oxide scale which was composed of Al2O3 and spinel Ni(Cr,Al)2O4. With 70ppm Y addition, the oxidation weight gain was decreased from 12.6g/m2 for the alloy without Y addition to 5.3g/m2, and the oxidation rate was significantly decreased. Besides, the internal nitride also disappeared after Y doping because of the increasing oxidation scale adherence and the decreasing of oxidation products. In this study, 660ppm Y addition alloy showed the best oxidation resistance.

scholarly journals Isothermal Oxidation Behavior of Novel Al2O3 / NiCrAlY / Ti3Al System at 850�C

2020 ◽  
Vol 71 (5) ◽  
pp. 106-116
Author(s):  
Alexandra Banu ◽  
Alexandru Paraschiv ◽  
Simona Petrescu ◽  
Irina Atkinson ◽  
Elena Maria Anghel ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aerospace Applications

The novel Al2O3 / NiCrAlY /alfa2-Ti3Al system obtained by APS technique was tested against long (500h) isothermal oxidation at 850�C in air for prospective use in aerospace applications. EDX-SEM, X-ray diffraction (XRD) and Raman investigations were conducted to substantiate structural, textural and mass gain modifications underwent by the Al2O3 / NiCrAlY /alfa2-Ti3Al system in comparison with bare alfa2-Ti3Al and NiCrAlY /alfa2-Ti3Al system. Improved oxidation resistance of the double-coated system is based on moderate oxygen and thermal barrier role played by the mixture of delta - and alfa-Al2O3 present in the top ceramic coat.

Effect of Hf Content on Oxidation Resistance of Single Crystal Superalloy at 1000°C

2014 ◽  
Vol 915-916 ◽  
pp. 562-566 ◽  
Author(s):  
Z.X. Shi ◽  
Shi Zhong Liu ◽  
M. Han ◽  
J.R. Li
Keyword(s):  
Grain Size ◽  
Single Crystal ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Oxidation Resistance ◽  
Isothermal Oxidation ◽  
Single Crystal Superalloy ◽  
Ambient Atmosphere ◽  
Directionally Solidified ◽  
Better Than

The specimens of single crystal superalloy DD6 with 0.10% Hf and 0.47% Hf were prepared in the directionally solidified furnace. The effect of Hf content on the isothermal oxidation resistance of the second generation single crystal superalloy DD6 was studied at 1000°Cin ambient atmosphere. Morphology of oxides was examined by SEM, and their composition was analyzed by XRD and EDS. The experimental results show that the oxidation resistance of DD6 alloy with 0.47% Hf is better than that of the alloy with 0.10% Hf. The alloy with different Hf content all obeys parabolic rate law during oxidation for 100h at 1000°C. The increase of Hf content can promote the Al2O3 formation and decreases the proportion of NiO. The oxide grain size and the thickness of the oxide layer all reduce with increasing of Hf content. The oxide scale of the alloy with different Hf content is made up of an outer NiO layer with a small amount of Co3O4, inner Al2O3 and Cr2O3 layer with a small amount of TaO2.

scholarly journals Oxidation Behavior of Multilayer Hard Coatings (TiCN/Al2O3/TiN) in Process of Recycling Coated Multicomponent Hardmetal Scrap

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1796 ◽  
Author(s):  
Hai Kuang ◽  
Dunqiang Tan ◽  
Wen He ◽  
Zhiqiang Yi ◽  
Zhihang Zou ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Hard Coatings ◽  
Hard Alloys ◽  
Al2o3 Layer ◽  
Good Oxidation Resistance ◽  
Element Diffusion ◽  
Negative Effect ◽  
Al2o3 Phase

The coating is one of the biggest problems in the recycling of coated multicomponent hardmetal scraps. The isothermal oxidation behavior of WC-Co multicomponent cemented carbide inserts with a TiCN/Al2O3/TiN hard coating in the recycling process was investigated. The oxidation rate slowed down as the protective coating blocked element diffusion. A rapid oxidation rate was obtained when they were milled into powders and isothermally oxidized at 900 °C. A rapid path for element diffusion was provided by the defects, which were promoted by stress, expansion, and gas volatilization. Both the TiN and TiCN layers were oxidized to a porous TiO2 scale, while the Al2O3 phase remained and the dense Al2O3 layer acted as a barrier for its good oxidation resistance. Pieces of the Al2O3 layer were obviously seen in the final oxides. This provides critical information to reduce the negative effect of coatings and improve the performance of recycled WC powders and hard alloys.

Liquid-Phase Siliconizing and Aluminizing at the Surface of a Ti3Al-Based Alloy and Improvement in Oxidation Resistance

2004 ◽  
Vol 19 (4) ◽  
pp. 1050-1057 ◽  
Author(s):  
Hua-Ping Xiong ◽  
Yong-Hui Xie ◽  
Wei Mao ◽  
Yun-Feng Chen ◽  
Xiao-Hong Li
Keyword(s):  
Liquid Phase ◽  
Oxidation Resistance ◽  
Energy Dispersive Spectrometer ◽  
Isothermal Oxidation ◽  
Diffusion Reaction ◽  
X Ray Diffraction ◽  
Inexpensive Method ◽  
X Ray ◽  
Outermost Surface ◽  
Modified Layer

A simple and inexpensive method to modify the surface of a Ti3Al-based alloy, liquid-phase siliconizing and aluminizing by an Al-Si alloy, has been proposed. The surface modification at 1013 K for 10 min using Al-10 wt% Si melt resulted in a modified layer with a thickness of about 21 μm, composed of TiAl3 and TiSi2. The coating improved the isothermal oxidation resistance of the Ti3Al-based alloy at 1073 K. A continuous alumina-rich scale was formed at the outermost surface after oxidation. SiO2 was detectable in the oxide scale. The results of x-ray diffraction and x-ray energy dispersive spectrometer analysis showed that during oxidation, some of the TiSi2 in the coating was oxidized to SiO2. In the meantime, the TiSi2 was reduced to a lower silicide, Ti5Si4. The change of the surface microstructure after oxidation and the diffusion reaction between the coating and the Ti3Al substrate were also discussed.

Isothermal Oxidation Behavior of a New Directionally Solidified Ni-Base Superalloy in Air at Different Temperature

2010 ◽  
Vol 654-656 ◽  
pp. 538-541
Author(s):  
Lei Wang ◽  
Yan Huang ◽  
Zhuo Zhao ◽  
Yang Liu ◽  
Jian Tao Wu ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxidation Behaviour ◽  
Diffusion Activation Energy ◽  
Directionally Solidified ◽  
Temperature Range ◽  
Parabolic Law ◽  
Diffusion Activation ◽  
Base Superalloy

The isothermal oxidation behaviour under static atmosphere of a new directionally solidified Ni-base superalloy was investigated. The results showed that the oxidation kinetics curves of the alloy follow parabolic law in the temperature range of 750-950°C. The diffusion activation energy Q is to be about 244.86 kJ•mol-1 and the oxidation within this temperature range is mainly controlled by Cr3+ diffusion among Cr2O3 oxidation film. The oxidation resistance grade of the alloy is perfect anti-oxidation within 750-850°C, and anti-oxidation within 900-950°C. The oxidation film can be divided into TiO2, Cr2O3+TiTaO4+NiCr2O4, Al2O3 and TiN layers, from the surface to inside. Priority oxidation and the inside oxidation of Al are considered with the oxidation of Ti and the depletion of Cr, and it is the key point for the improving of oxidation resistance.

Sign in / Sign up

Export Citation Format

Share Document