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1
Lazurenko, Daria V., Mikhail G. Golkovsky, Andreas Stark, Florian Pyczak, Ivan A. Bataev, Alexey A. Ruktuev, Ivan Yu Petrov, and Ilia S. Laptev. "Structure and Properties of Ti-Al-Ta and Ti-Al-Cr Cladding Layers Fabricated on Titanium." Metals 11, no. 7 (July 19, 2021): 1139. http://dx.doi.org/10.3390/met11071139.
Повний текст джерелаАнотація:
Being one of the most high-demand structural materials, titanium has several disadvantages, including low resistance to high-temperature oxidation and wear. The properties of titanium and its alloys can be improved by applying protective intermetallic coatings. In this study, 2 mm thick Ti-Al-Ta and Ti-Al-Cr layers were obtained on titanium workpieces by a non-vacuum electron-beam cladding. The microstructure and phase compositions of the samples were different for various alloying elements. The Cr-containing layer consisted of α2, γ, and B2 phases, while the Ta-containing layer additionally consisted of ω′ phase (P3¯m1). At the same atomic concentrations of aluminum and an alloying element in both layers, the volume fraction of the B2/ω phase in the Ti-41Al-7Ta alloy was significantly lower than in the Ti-41Al-7Cr alloy, and the amount of γ phase was higher. The Ti-41Al-7Cr layer had the highest wear resistance (2.1 times higher than that of titanium). The maximum oxidation resistance (8 times higher compared to titanium) was observed for the Ti-41Al-7Ta layer.
2
Savkovs, Konstantins, Margarita Urbaha, and Viktors Feofanovs. "Determining High-Temperature Oxidation Resistance of (TI-Al-X-N) Based Coatings for Titanium Alloys." Solid State Phenomena 320 (June 30, 2021): 66–71. http://dx.doi.org/10.4028/www.scientific.net/ssp.320.66.
Повний текст джерелаАнотація:
Basic titanium alloys are successfully used in modern aviation GTE (gas turbine engine). They are used for parts of a compressor and partly in low pressure part of turbine (intermetallic Ti-Al alloys) due to their high specific strength and at the same time low density, high corrosion resistance but can be used only up to 700 °C. The paper deals with the results of heat resistance testing at 750 °C of Ti-Al-(X)+N based thin ion-plasm multilayers coatings, with different priority of monolayers- intermetallic, conglomerate or nitride for gas turbine engine (GTE) blades from titanium alloys. All coatings showed high resistance during the test, with a maximum efficiency 42.8 of coating with a priority of conglomerate after 30 hours of testing.
3
Vojtěch, Dalibor, and Tomáš Popela. "Structure and High-Temperature Oxidation of Ti-Al-Nb and Ti-Al-Ta Intermetallics." Key Engineering Materials 465 (January 2011): 227–30. http://dx.doi.org/10.4028/www.scientific.net/kem.465.227.
Повний текст джерелаАнотація:
Ti-Al based intermetallics are prospective high-temperature materials showing low weight combined with a relatively high strength, high creep resistance and good oxidation resistance at high temperatures. Beside Ti and Al, these materials commonly contain other additives modifying their properties. In the present work, structure and oxidation resistance of two Ti-Al-Nb and Ti-Al-Ta alloys are studied. The alloys are prepared by vacuum arc melting and oxidation is conducted in air at 800-1000°C. It is found that there are significant differences in the structure depending on the ternary additive. There are also differences in oxidation behavior and these differences are discussed in relation to oxidation mechanism.
4
Schütze, Michael, and Simone Friedle. "Oxidation Behavior of Intermetallic Titanium Aluminide Alloys." MRS Proceedings 1516 (2012): 77–88. http://dx.doi.org/10.1557/opl.2012.1666.
Повний текст джерелаАнотація:
ABSTRACTAbove 750-800°C oxidation becomes a serious life time issue for the new group of intermetallic light-weight high temperature alloys based on titanium aluminides (TiAl). Fast growing titanium oxide competes with protective alumina as a surface scale in the oxidation reaction by which the formation of a slow-growing protective oxide scale is prevented. The key to the development of alloys with sufficient oxidation resistance is the understanding of the thermodynamic and kinetic situation during the oxidation process. The latter is influenced by the type of alloying elements, the Al- and Ti-activities in the alloy, the oxidation temperature and the environment (e.g. dry or humid air, etc.). This paper provides a comprehensive summary of the oxidation mechanisms and the parameters influencing oxide scale formation. Besides the role of metallic alloying elements, the halogen effect will also be discussed. The paper finishes with recent results concerning the prevention of oxidation-induced room temperature embrittlement of TiAl alloys.
5
Sienkiewicz, Judyta, Seiji Kuroda, Hideyuki Murakami, Hiroshi Araki, Maciej Giżyński, and Krzysztof J. Kurzydłowski. "Fabrication and Oxidation Resistance of TiAl Matrix Coatings Reinforced with Silicide Precipitates Produced by Heat Treatment of Warm Sprayed Coatings." Journal of Thermal Spray Technology 27, no. 7 (September 5, 2018): 1165–76. http://dx.doi.org/10.1007/s11666-018-0751-x.
Повний текст джерелаАнотація:
Abstract Ti-Al-based intermetallics are promising candidates as coating materials for thermal protection systems in aerospace vehicles; they can operate just below the temperatures where ceramics are commonly used, and their main advantage is the fact that they are lighter than most other alloys, such as MCrAlY. Therefore, Ti-Al-Si alloy coatings with five compositions were manufactured by spraying pure Ti and Al-12 wt.% Si powders using warm spray process. Two-stage hot pressing at 600 and 1000 °C was applied to the deposits in order to obtain titanium aluminide intermetallic phases. The microstructure, chemical composition, and phase composition of the as-deposited and hot-pressed coatings were investigated using SEM, EDS, and XRD. Applying of hot pressing enabled the formation of dense coatings with porosity around 0.5% and hard Ti5(Si,Al)3 silicide precipitates. It was found that the Ti5(Si,Al)3 silicides existed in two types of morphologies, i.e., as large particles connected together and as small isolated particles dispersed in the matrix. Furthermore, the produced coatings exhibited good isothermal and cyclic oxidation resistance at a temperature of 750 °C for 100 h.
6
Batool, Syeda Ammara, Akhlaq Ahmad, Abdul Wadood, Abdul Mateen, and Syed Wilayat Hussain. "Development of Lightweight Aluminum-Titanium Alloys for Aerospace Applications." Key Engineering Materials 778 (September 2018): 22–27. http://dx.doi.org/10.4028/www.scientific.net/kem.778.22.
Повний текст джерелаАнотація:
Aluminum (Al) and Titanium (Ti) based lightweight alloys have been a topic of discussion and research for a few decades now. Resulting alloys with hard intermetallic phases in Al-Ti binary system have good microstructural and mechanical properties including low densities, high specific strength, better resistance against oxidation and corrosion which are highly desirable in aerospace industry. Such an alloy system was studied in our research. Powder metallurgy (PM) was used as processing route because of its economical and easy operation. Samples were prepared using metallic powders of Aluminum (Al) and Titanium (Ti) with varying compositions of 95 at.% Al-Ti, 90 at.% Al-Ti and 88 at.% Al-10 at.% Ti-2 at.% SiC. After compaction, pressureless sintering was carried out at 620°C for several hours in Argon atmosphere followed by annealing resulting in a reasonably dense Al-Ti alloy. Microstructure and phase composition of alloy was analyzed by Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS), respectively. Hardness was evaluated by Vickers micro indentation test. An increase in hardness was observed. Sample containing reinforcement particles (SiC) demonstrated highest value of hardness.
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Fröhlich, Maik, Reinhold Braun та Christoph Leyens. "Ti-Al-Cr Based Coatings for High Temperature Oxidation Protection of γ-TiAl". Materials Science Forum 638-642 (січень 2010): 1306–11. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1306.
Повний текст джерелаАнотація:
In this study the oxidation resistance of Ti-45Al-8Nb (at.%) alloy coated with quaternary Ti-Al-Cr-X layers (X = Si, Hf, Y, Zr and W) was investigated. The Ti-Al-Cr-Si, Ti-Al-Cr-Hf and Ti-Al-Cr-Y coated specimens were exposed to air at 950°C under cyclic conditions, whereas the samples with Ti-Al-Cr-Zr and Ti-Al-Cr-W coatings were thermally cycled at 1000°C. After the maximum exposure time period of 1000 1h-cycles or failure cross-sections of the samples were examined by means of SEM and EDS to analyse the microstructural evolution. At initial stages of exposure, all intermetallic layers formed a thin alumina layer on top, providing a diffusion barrier to oxygen. But interdiffusion between coating and substrate caused depletion of the Ti(Cr,Al)2 Laves phase in the intermetallic layers, which promoted the formation of alumina, as well as transformation into Ti-rich B2-phase. Coarsening of the latter phase beneath the alumina scale resulted in a higher oxidation resistance compared to that of ternary Ti-Al-Cr coating.
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Donchev, Alexander, Michael Schütze, Andreas Kolitsch, and Rossen Yankov. "Economic Surface Treatment of Ti-Alloys to Improve their Resistance against Environmental High Temperature Attack." Key Engineering Materials 551 (May 2013): 109–13. http://dx.doi.org/10.4028/www.scientific.net/kem.551.109.
Повний текст джерелаАнотація:
High temperature Ti-alloys are usually sophisticated and hence expensive. To allow the use of cheaper alloys at elevated temperatures an economic and easy to apply procedure was developed to improve their high temperature capability. The treatment consists of a combination of Al-enrichment in a shallow surface region plus additional fluorination. The Al-enrichment at elevated temperatures leads to the formation of intermetallic TiAl-phases. These phases improve the oxidation resistance of Ti-alloys but not to a sufficient extent. An additional fluorine treatment of the Al-enriched surface leads to the formation of a protective alumina scale due to the fluorine effect. In this paper results from high temperature exposure tests performed on different Ti-alloys without any treatment and with a combination of Al-treatment plus fluorination are presented. The results are discussed in the view of the use of the optimized Ti-components for several high temperature applications.
9
Braun, Reinhold, Klemens Kelm, Arutiun P. Ehiasarian та Papken Eh Hovsepian. "Oxidation Protection of γ-TiAl Alloys by Intermetallic Ti-Al-Cr-Zr Coatings". MRS Proceedings 1516 (2012): 89–94. http://dx.doi.org/10.1557/opl.2012.1562.
Повний текст джерелаАнотація:
ABSTRACTThe oxidation behavior of γ-TiAl specimens coated with an intermetallic Ti-49Al-34Cr-4Zr layer was investigated at 1000°C under cyclic conditions in laboratory air. The 11 μm thick coating was produced using a combined technique of high power impulse magnetron sputtering and unbalanced magnetron sputtering. The as-deposited coating exhibited a dense layered structure and excellent adhesion to the substrate. The Ti-Al-Cr-Zr coating possessed high oxidation resistance associated with the formation of a thin continuous alumina scale for exposure time periods exceeding 1000 cycles of 1 h dwell time at 1000°C. During the high temperature exposure, the coating being amorphous in the as-deposited condition became crystalline exhibiting different polytypes of Ti(Cr,Al)2Laves phases with Ti probably partially substituted by Zr and Nb. Due to alumina formation and interdiffusion the coating was depleted in aluminum and chromium as well as enriched in titanium. After 1000 cycles at 1000°C, the coating consisted of an outer layer of the hexagonal C14 Laves phase and an inner layer of a probably orthorhombic phase whose structure was not yet determined. In both layers, pores and fine precipitates rich in Zr and Y were found.
10
Sasaki, Tomohiro, Takahiro Yagi, and Takehiko Watanabe. "Aluminizing of TiAl-Based Alloy Using Thermal Spray Coating." Materials Science Forum 654-656 (June 2010): 1884–87. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1884.
Повний текст джерелаАнотація:
Aluminizing the surface of a TiAl-based alloy (49.1 at% Al) was carried out by thermally spraying a pure aluminum coating and subsequent diffusion treatment at 1100°C. The influence of the diffusion time for the formation of Ti-Al intermetallic phases in the coating layers and the oxidation resistance of the aluminized TiAl-based alloys were investigated. The layer formed on the outermost surface was comprised of the Al-rich intermetallic T2iAl5 and contained pores. On the other hand, an intermediate layer consisting of TiAl2 and TiAl was formed between the outermost layer and the substrate. The thickness of the outermost layer decreased as the diffusion time increased, while the thickness of the intermediate layer increased. In addition, the coating/substrate interface changed from a wavy to a linear form with the growth of the intermediate layer. The aluminized coating showed good oxidation resistance at 900°C for all diffusion times.
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Góral, M., P. C. Monteiro, P. Sosnowy, M. Woźniak, T. Kubaszek, and B. Kościelniak. "The formation of Si-aluminide coating formed by plasma spraying and subsequent diffusion annealing on Ti-Al-7Nb intermetallic alloy." Archives of Materials Science and Engineering 117, no. 2 (October 1, 2022): 49–56. http://dx.doi.org/10.5604/01.3001.0016.1775.
Повний текст джерелаАнотація:
In the article, the kinetic growth phenomena of aluminide coating formed by plasma spraying pure Al-Si powder and subsequent diffusion annealing on TiAl intermetallic alloy in inert atmosphere were investigated. The Al-Si powder was thermal sprayed (APS) on TiAl7Nb intermetallic alloy and annealed in Ar atmosphere during 5, 15, 30, 60, 240 and 480 min. The kinetic growth of the coating was observed using the scanning electron microscopy method (SEM), and chemical composition was analysed using the EDS method. The Kirkendall Effects pores formation, as well as titanium silicides on the grain boundary of TiAl3, was found. The oxidation resistance of the developed coating might be analysed in further work. The developed coating might be used for the production of protective aluminide coatings on TiAl intermetallic alloys. The description of aluminide coating formation in a new technological process.
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Basuki, Eddy, Djoko Prajitno, and Pawawoi. "Oxidation Behavior of Aluminide Coated Ti-Al-Cr-Nb-Zr-Y Alloys at High Temperatures." Solid State Phenomena 227 (January 2015): 345–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.345.
Повний текст джерелаАнотація:
In this study the oxidation behavior of diffusion aluminide coating containing layers of TiAl3 and TiAl2, develop on a substrate of Zr-Y doped α2-Ti3Al/γ-TiAlCrNb intermetallic alloy using pack aluminizing method, was investigated isothermally at 800°C, 900°C, and 1000°C under atmospheric air pressure. The pack cementation was carried out at 850°C for 25 hours in a pack containing 20%-wt Al, 2%-wt NH4Cl, and 78%-wt Al2O3.The phases in the coatings and oxide layers were examined by optical and scanning electron microscopy as well as X-ray diffraction method, while chemical composition of the oxides and phases were examined with EDS attached on the SEM. The experimental results showed that the addition of Zr and Y increases the oxidation resistance of the coating by formation of complex oxides mainly of Al2O3 at the coating surfaces and sub-surface. Combination of oxidation and interdiffusion process cause transformation of TiAl3 layer to TiAl2 that decrease the oxidation resistance through the formation of TiO2 rod crystals on the junction between TiAl2 and Al2O3 in the outer layer.
13
Obert, Susanne, Alexander Kauffmann, Rupert Pretzler, Daniel Schliephake, Frauke Hinrichs, and Martin Heilmaier. "The Creep and Oxidation Behaviour of Pesting-Resistant (Mo,Ti)5Si3-Containing Eutectic-Eutectoid Mo-Si-Ti Alloys." Metals 11, no. 1 (January 18, 2021): 169. http://dx.doi.org/10.3390/met11010169.
Повний текст джерелаАнотація:
In this study we present a series of light-weight (6.24 to 6.42 g/cm3), Ti-rich Mo-Si-Ti alloys (≥40 at.% nominal Ti content) with the hitherto best combination of pesting and creep resistance at 800 and 1200 °C, respectively. This has been achieved by fine-scaled eutectic-eutectoid microstructures with substantial fractions of primarily solidified (Mo,Ti)5Si3. (Mo,Ti)5Si3 was found to be oxidation-resistant in these alloys and also beneficial for the creep resistance. The enhanced solidus temperature is of specific relevance with respect to the latter point. The creep resistance is competitive to the non-pesting resistant, but most creep-resistant (among the Mo-Si-Ti alloys) eutectoid alloy Mo-21Si-34Ti developed by Schliephake et al. [Schliephake et al., in Intermetallics 104 (2019) pp. 133–142]. Moreover, it is favourably superior to the commercially applied Ni-based single crystal alloy CMSX-4 for the applied compressive loading conditions under vacuum.
14
Menon, E. S. K., T. R. Halladay, A. G. Fox, and R. Mahapatra. "Microstostructural Developments in Chill-Cast and Directionally Solidified Ti-44Al-11Nb Alloys." Microscopy and Microanalysis 5, S2 (August 1999): 866–67. http://dx.doi.org/10.1017/s1431927600017657.
Повний текст джерелаАнотація:
Studies aimed at improvements in the properties of titanium aluminides continue and efforts on optimizing the microstuctural parameters and a variety of processing techniques have attracted significant attention. In particular alloy compositions containing Ti-44to48at%Al and Nb as the major ternary addition (often with other minor alloying element additions) have been found quite promising. A fine fully lamellar structure in these TiAl-based intermetallic alloys has been reported to possess a combination of improved room temperature ductility, excellent fracture toughness, good oxidation resistance and creep properties. One of the serious problems associated with the TiAl-based alloys is the large grain size that develops in these alloys especially upon casting. A recent approach is to use directional solidification techniques in producing the TiAlbased alloys and it has been shown that desired orientations can indeed be produced by choice of suitable processing parameters.In this study, we have examined the microstructural features associated with chill-cast as well as directionally solidified Ti-44at%Al-l lat%Nb alloy.
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Donchev, Alexander, Mathias Galetz, Svea Mayer, Helmut Clemens та Michael Schütze. "The Use of Fluorine to Protect β-Solidifying γ-TiAl-Based Alloys against High-Temperature Oxidation". MRS Advances 2, № 25 (2017): 1361–67. http://dx.doi.org/10.1557/adv.2017.170.
Повний текст джерелаАнотація:
ABSTRACTLight-weight alloys based on intermetallic titanium aluminides (TiAl) are structural materials considered for high-temperature applications, e.g. in aero engines or automotive engines. TiAl alloys of engineering interest consist of two phases, the γ-TiAl and the α2-Ti3Al-phase. Recent developments have led to the so-called TNM alloys (T = TiAl; N = Nb; M = Mo) with an Al-content of 43.5 at.%. These alloys also possess the disordered body centered cubic β-Ti(Al)-phase at elevated temperatures, which ensures a better hot-workability compared to conventional two-phase alloys. However, the relatively low Al content (< 45 at.%) limits the high-temperature capability due to reduced oxidation resistance. This impedes their application in a temperature range above 800°C. The present work shows how the fluorine effect counteracts this disadvantage due to the formation of a protective alumina layer. The performance of the TNM alloy with the nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (at.%) is compared with another TNM alloy variant containing additional elements, such as Si and C, and the so-called GE alloy (Ti-48Al-2Cr-2Nb; at.%), which is already in use for turbine blades. The results of isothermal and thermocyclic high-temperature exposure tests of untreated and fluorine treated specimens will be compared. The effect of composition and microstructure of the alloys on the oxidation behavior with and without fluorine treatment are discussed.
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Knaislová, Anna, Pavel Novák, Filip Průša, Sławomir Cygan, and Lucyna Jaworska. "Preparation of TiAl15Si15 alloy by High Pressure Spark Plasma Sintering." Acta Metallurgica Slovaca 24, no. 2 (June 28, 2018): 174. http://dx.doi.org/10.12776/ams.v24i2.1064.
Повний текст джерелаАнотація:
<p class="AMSmaintext"><span lang="EN-GB">This work deals with preparation of intermetallic alloy TiAl15Si15 (wt. %) by powder metallurgy using Spark Plasma Sintering method. Ti-Al-Si alloys are known as materials with low density, relatively good mechanical properties in comparison with their density and good oxidation and corrosion resistance at elevated temperatures. Preparation of intermetallics by melting metallurgy is very problematic. Powder metallurgy using reactive sintering followed by suitable compaction seems to be a promising method. In this work, TiAl15Si15 alloy was prepared by reactive sintering, milling and by unique ultra-high pressure Spark Plasma Sintering within the framework of international cooperation in Krakow. For the comparison it was also prepared by conventional Spark Plasma Sintering. The results show that higher pressure of sintering decreases the porosity of compact sample and increases mechanical properties, especially hardness.</span></p>
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Hall, Ernest L., and Shyh-Chin Huang. "Phase distribution in rapidly solidified TiAl alloys." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 322–23. http://dx.doi.org/10.1017/s0424820100153580.
Повний текст джерелаАнотація:
There is at present a great deal of interest in the intermetallic compound γ-TiAl, particularly with regard to its use as an aircraft engine or aerospace structural material. This compound possesses an attractive combination of properties, including high melting temperature, low density, high modulus, and good oxidation and creep resistance, but is somewhat deficient in room temperature ductility due to its crystal structure, which is the Ll0 face-centered tetragonal structure consisting of alternating (002) planes of Ti and Al. The Ti-Al equilibrium phase diagram in the vicinity of γ-TiAl shows that γ-TiAl forms via a peritectic reaction and thus, in order to minimize segregation and to insure maximum homogeneity, it is desirable to produce γ-TiAl alloys by rapid solidification. It is then useful, in order to establish a baseline for advanced alloy design, to have an understanding of the microstructures resulting from rapid solidification. In this paper, we report the results of microstructural studies of binary Ti-Al alloys varying in stoichiometry from 46 to 70 at. % Al which were rapidly solidified into the form of ribbon using melt spinning.
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Wen, Jing, Xin Chu, Yuankui Cao, and Na Li. "Effects of Al on Precipitation Behavior of Ti-Nb-Ta-Zr Refractory High Entropy Alloys." Metals 11, no. 3 (March 20, 2021): 514. http://dx.doi.org/10.3390/met11030514.
Повний текст джерелаАнотація:
Addition of Al can decrease density and improve oxidation resistance of refractory high entropy alloys (RHEAs), but may cause complicated precipitation and further affect mechanical properties. The present work studied the microstructural evolution of Al-contained RHEAs at elevated temperatures. The effects of Al on precipitation behavior were discussed. Results show that, TiNbTa0.5ZrAlx alloys (x ≤ 0.5) have single BCC (Body Centered Cubic) structure, but the primary BCC phase is supersaturated. Precipitation of BCC2(Nb,Ta)-rich solid solution phase, HCP(Zr,Al)-rich intermetallic phase, and ordered B2 phase can occur during heat treatment at 600~1200 °C. The precipitation of BCC2 phase mainly exists in RHEAs with low content of Al, while HCP (Hexagonal Close Packed) precipitates prefer to form in RHEAs with high content of Al. Interestingly, ordered B2 precipitates with fine and basket-weave structure can form in TiNbTa0.5ZrAl0.5 alloy after annealing at 800 °C, producing significant precipitation hardening effect.
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Bednarczyk, I., D. Kuc, and G. Niewielski. "Influence of Cumulative Plastic Deformation on Microstructure of the Fe-Al Intermetallic Phase Base Alloy." Archives of Metallurgy and Materials 59, no. 3 (October 28, 2014): 987–91. http://dx.doi.org/10.2478/amm-2014-0191.
Повний текст джерелаАнотація:
Abstract This article is part of the research on the microstructural phenomena that take place during hot deformation of intermetallic phase-based alloy. The research aims at design an effective thermo - mechanical processing technology for the investigated intermetallic alloy. The iron aluminides FeAl have been among the most widely studied intermetallics because their low cost, low density, good wear resistance, easy of fabrication and resistance to oxidation and corrosion. There advantages create wide prospects for their industrial applications for components of machines working at a high temperature and in corrosive environment. The problem restricting their application is their low plasticity and their brittle cracking susceptibility, hampers their development as construction materials. Consequently, the research of intermetallic-phase-based alloys focuses on improvement their plasticity by hot working proceses. The study addresses the influence of deformation parameters on the structure of an Fe-38% at. Al alloy with Zr, B Mo and C microadditions, using multi – axis deformation simulator. The influence of deformation parameters on microstructure and substructure was determined. It was revealed that application of cumulative plastic deformation method causes intensive reduction of grain size in FeAl phase base alloy.
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Braun, Reinhold, Maik Fröhlich, and Christoph Leyens. "Intermetallic Ti-Al-Cr Based Layers and Zirconia Topcoats Deposited on Gamma Titanium Aluminides for Environmental Protection." Advanced Materials Research 278 (July 2011): 497–502. http://dx.doi.org/10.4028/www.scientific.net/amr.278.497.
Повний текст джерелаАнотація:
. Intermetallic Ti-Al-Cr layers with small additions of Si, Zr, W, and Y were deposited on γ-TiAl specimens using magnetron sputtering. The oxidation behaviour of the coated γ-TiAl alloy was studied in the temperature range between 950 and 1000°C under cyclic oxidation conditions in air. Compared to the bare substrate material, the coatings exhibited higher oxidation resistance. During prolonged exposure the intermetallic layers degraded losing their capability to form a protective alumina scale. On coated γ-TiAl samples zirconia topcoats were deposited by electron beam physical vapour deposition. These thermal barrier coating systems exhibited lifetimes exceeding the maximum exposure length of 1000 1 h cycles at 950°C, but failed at 1000°C. Failure was caused by degradation of the bond coats resulting in spallation of the thermally grown oxides.
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Zhao, Mi, Wei Ye, Mengyuan Zhu, Yuteng Gui, Wei Guo, Shusen Wu, and Youwei Yan. "From Mo–Si–B to Mo–Ti–Si–B Alloys: A Short Review." Materials 16, no. 1 (December 20, 2022): 3. http://dx.doi.org/10.3390/ma16010003.
Повний текст джерелаАнотація:
Mo–Si–B alloys have attracted considerable research interest during the last several decades due to their high melting points, excellent high-temperature strength and relatively good oxidation resistance. However, insufficient room-temperature fracture toughness and high-temperature oxidation resistance restrain their further application. Generally, a sufficient volume fraction of BCC-Mo solid-solution phase, providing the ductility, and a high Si content, responsible for the formation of passive oxide scales, is difficult to achieve simultaneously in this ternary system. Recently, macroalloying of Ti has been proposed to establish a novel phase equilibrium with a combination of enough BCC phase and intermetallic compounds that contain a large amount of Si. In this article, the development history from the ternary Mo–Si–B to the quaternary Mo–Ti–Si–B system was reviewed. It was found that the constitution phases could be easily tailored by changing the Ti content. In this regard, better performance of mechanical properties and oxidation resistance can be obtained through proper alloy design. In-depth understanding of the advantages of the quaternary alloys over their ternary ancestors may contribute to bringing about a new concept in designing novel ultra-high-temperature structural materials.
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Jang, Y. D., Sung Jin Kim, and Dong Bok Lee. "Oxidation of (Al+8%Mn)3Ti Intermetallics Synthesized by Mechanical Alloying." Materials Science Forum 449-452 (March 2004): 825–28. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.825.
Повний текст джерелаАнотація:
The oxidation behavior of (Al+8 at.%Mn)3Ti alloys prepared by mechanical alloying followed by cold isostatic pressing and sintering at high temperatures was investigated at 1000 and 1100°C up to 300 hr in air. Since the Al2O3 barrier layer having some dissolved ions of Ti, and Mn formed, the oxidation resistance of the prepared alloys was excellent.
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Jia, Qianqian, Deyuan Li, Zhuang Zhang, Nannan Zhang, and Wenzhen Zhao. "Comparison of oxidation resistance of Al–Ti and Al–Ni intermetallic formed in situ by thermal spraying." Materials Research Express 6, no. 9 (July 3, 2019): 096408. http://dx.doi.org/10.1088/2053-1591/ab2cfc.
Повний текст джерела
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Bae, Chul-Hong, Seong-Ho Ha, Bong-Hwan Kim, Young-Ok Yoon, Hyun-Kyu Lim, Shae K. Kim, and Young-Jig Kim. "Effects of Constituent Phases on Oxidation Kinetics of Al–Mg Alloys Containing a Trace of Ca." Journal of Nanoscience and Nanotechnology 21, no. 3 (March 1, 2021): 2067–70. http://dx.doi.org/10.1166/jnn.2021.18945.
Повний текст джерелаАнотація:
In this study, the effects of constituent phases on the oxidation kinetics of an Al-7 mass%Mg alloy containing a trace of Ca were investigated. A Mg+Al2Ca master alloy was used to add Mg and Ca simultaneously. Scheil-Gulliver cooling by thermodynamic calculation showed that the addition of Ca led to the formation of Ca-based intermetallic compounds, such as Al4Ca and Laves C36, after solidification. Based on weight increase indicated by the oxidation test and surface analysis, it was found that the presence of Ca-based phases significantly improved the oxidation resistance and slowed down the oxidation rates. Based on the review of phase diagrams with oxygen partial pressure by thermodynamic calculation, it was thought that in the initial oxidation, MgO and MgAl2O4 were formed on the surfaces of the Al–Mg alloys, leading to further oxidation. The Ca-based intermetallic compounds formed Ca–Mg–Al based oxides, which possibly contributed to the formation of a relatively dense oxide layer.
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Bauer, Peter-Philipp, Lisa Klamann, Radosław Swadźba, and Nadine Laska. "Effect of Si Content on Deposition and High-Temperature Oxidation of Al-Si Coatings Obtained by Magnetron Sputtering PVD Method." Coatings 12, no. 6 (June 18, 2022): 859. http://dx.doi.org/10.3390/coatings12060859.
Повний текст джерелаАнотація:
Intermetallic Al-Si-based coatings can greatly increase the oxidation resistance of γ-TiAl alloys. However, the effects of the Si addition are not fully understood. Therefore, it is difficult to determine the Si content that is optimal for oxidation resistance. Therefore, pure Al and several Al-Si coatings with varying Si contents between 1 and 81 at.% were studied. The coatings were produced using a combinatorial magnetron sputtering process. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used for structure and chemical analysis. The phases were identified by X-ray diffraction. Cyclic oxidation tests at 900 °C were conducted up to 5000 cycles of 1 h each and subsequently evaluated by thermogravimetric analysis. Si addition in the range of 1 to 12 at.% did not deteriorate the oxidation resistance compared to a pure Al coating up for 1000 cycles (1 h) of oxidation at 900 °C, while higher Si contents led to a high mass gain. For oxidation times up to 5000 cycles (1 h), a sufficient thickness of the coatings is crucial for good oxidation resistance. The main effect of Si addition is to enhance the transformation speed of the deposited Al and Si to the high temperature stable Ti(Al,Si)3 phase during the heat treatment. Si additions of up to 12 at.% led to increased initial mass gains and a decrease in the oxidation rates during subsequent exposures compared to pure Al coatings.
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Simões, F., and B. Trindade. "Morphology and Structure of Compacted Coated Powders Studied by SEM and TEM." Microscopy and Microanalysis 14, S3 (September 2008): 31–34. http://dx.doi.org/10.1017/s1431927608089290.
Повний текст джерелаАнотація:
The interest in titanium based intermetallics, such as Ti-Al alloys, for high temperatures applications has been increased in recent years mainly due to their high plastic deformation resistance, chemistry stability (oxidation and corrosion resistance) and creep and fatigue resistance at high temperatures. However, the industrial application of Ti-Al intermetallics is very limited so far, due to the lack of ductility and fracture toughness at room temperature with associated processing difficulties. To overcome this problem and to improve mechanical properties of Ti-Al intermetallics, a powder mixture with atomic composition of Ti52Al48 was synthesized by mechanical alloying (MA) and subsequently coated with a ductile element (aluminium), by d.c. magnetron sputtering. Later, in order to obtain a compacted material, as final step, the coated MA'ed powders were submitted to hot isostatic pressing (HIP), giving rise to a bulk material. The aim of the current work is to understand the influence of coating layer in mechanical alloyed (MA'ed) powders and the influence in bulk material properties.
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Goral, Marek, Grzegorz Moskal, Lucjan Swadźba, and Marek Hetmańczyk. "The Influence of Silicon Amount on Structure of Si Modified Aluminide Coating Deposited on Ti46Al7Nb Alloy by Slurry Method." Key Engineering Materials 465 (January 2011): 251–54. http://dx.doi.org/10.4028/www.scientific.net/kem.465.251.
Повний текст джерелаАнотація:
The alloys based on the intermetallic phases from Ti-Al system are materials which, on the grounds of their resistance characteristics, could be widely used in automotive and aerospace applications. The insufficient oxidation resistance of this alloys could be increased by the coating silicon modification. The technology used in this investigation was the immersion in water-based slurry containing metal powders. MHI high-Nb (14 wt %) alloy has been used as the research material for the coatings produced. The water-based slurries containing Al and Si powders have been prepared with 0-80 wt % Si content. The diffusion treatment has been done at 950oC in 4h in the Ar atmosphere. The investigation has showed that the thickness of the coatings ranged from 30 to 40 m. The structure of the Si-modified aluminide coatings is as follows: (a) outer zone consisting of TiAl3 phase and titanium silicides, (b) middle zone consisting of columnar titanium silicides in phase TiAl3 matrix (c) the inner zone consisting of TiAl2 phase. The XRD phase analysis has confirmed Ti5Si3 creation and, in case of the high silicon content (above 20 wt %), also other silicides: types Ti5Si4,TiSi2,TiSi
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Srigiofun, Pajaree, Panyawat Wangyao, and Tanaporn Rojhirunsakool. "Effect of Alloying Modification in Arc Melted Hastelloy X on Microstructures and Oxidation Resistance at Elevated Temperatures." Key Engineering Materials 658 (July 2015): 8–13. http://dx.doi.org/10.4028/www.scientific.net/kem.658.8.
Повний текст джерелаАнотація:
The present research work has an aim to modify microstructure and oxidation behavior of Hastelloy X, a solid solution nickel base alloy, by both aluminium and titanium additions by mean of arc melting process. The Hastelloy X was added both Al and Ti (50:50) for 2% 4% and 6% by weight and casted by vacuum arc melting furnace. Then all received specimens were performed heat treatment, which consist of solutioning treatment at 1175°C for 4 hours and aging temperatures for 760°C, 800°C and 845°C for 24 hours. From the obtained results, it was found that the amount of both Al and Ti additions as well as precipitation aging temperature provided significant effect on both final microstructure and oxidation behaviors at 900°C and 1000°C. Widmanstatten type of microstructure was found in many case. Intermetallic phase formation of molybdenum and chromium was also found in all cases by element mapping. This phase should be γ’-phase. Both aluminium and titanium additions could not provide beneficial effect on oxidation resistance tests at temperature of 900°C and 1000°C. However, with 4%wt. of both aluminium and titanium addition, it resulted in slightly increasing of oxidation resistance at temperature of 1000°C
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Xu, Zhen, Claire Utton, and Panos Tsakiropoulos. "A Study of the Effect of 5 at.% Sn on the Micro-Structure and Isothermal Oxidation at 800 and 1200 °C of Nb-24Ti-18Si Based Alloys with Al and/or Cr Additions." Materials 13, no. 1 (January 6, 2020): 245. http://dx.doi.org/10.3390/ma13010245.
Повний текст джерелаАнотація:
This paper presents the results of a systematic study of Nb-24Ti-18Si based alloys with 5 at.% Sn addition. Three alloys of nominal compositions (at.%), namely Nb-24Ti-18Si-5Cr-5Sn (ZX4), Nb-24Ti-18Si-5Al-5Sn (ZX6), and Nb-24Ti-18Si-5Al-5Cr-5Sn (ZX8), were studied to understand how the increased Sn concentration improved oxidation resistance. In all three alloys there was macrosegregation, which was most severe in ZX8 and the primary βNb5Si3 transformed completely to αNb5Si3 after heat treatment. The Nbss was not stable in ZX6, the Nb3Sn was stable in all three alloys, and the Nbss and C14-NbCr2 Laves phase were stable in ZX4 and ZX8. The 5 at.% Sn addition suppressed pest oxidation at 800 °C but not scale spallation at 1200 °C. At both temperatures, a Sn-rich area with Nb3Sn, Nb5Sn2Si, and NbSn2 compounds developed below the scale. This area was thicker and continuous after oxidation at 1200 °C and was contaminated by oxygen at both temperatures. The contamination of the Nbss by oxygen was most severe in the bulk of all three alloys. Nb-rich, Ti-rich and Nb and Si-rich oxides formed in the scales. The adhesion of the latter on ZX6 at 1200 °C was better, compared with the alloys ZX4 and ZX8. At both temperatures, the improved oxidation was accompanied by a decrease and increase respectively of the alloy parameters VEC (Valence Electron Concentration) and δ, in agreement with the alloy design methodology NICE (Niobium Intermetallic Composite Elaboration). Comparison with similar alloys with 2 at.% Sn addition showed (a) that a higher Sn concentration is essential for the suppression of pest oxidation of Nb-24Ti-18Si based alloys with Cr and no Al additions, but not for alloys where Al and Cr are in synergy with Sn, (b) that the stability of Nb3Sn in the alloy is “assured” with 5 at.% Sn addition, which improves oxidation with/out the presence of the Laves phase and (c) that the synergy of Sn with Al presents the “best” oxidation behaviour with improved scale adhesion at high temperature.
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Clemens, Helmut, and Wilfried Smarsly. "Light-Weight Intermetallic Titanium Aluminides – Status of Research and Development." Advanced Materials Research 278 (July 2011): 551–56. http://dx.doi.org/10.4028/www.scientific.net/amr.278.551.
Повний текст джерелаАнотація:
Development and processing of high-temperature materials is the key to technological progress in engineering areas where materials have to meet extreme requirements. Examples for such areas are the aerospace and automotive industries. New structural materials have to be stronger, stiffer and lighter to withstand the extremely demanding conditions in the next generation of aero- and automotive engines. Intermetallic -TiAl based alloys exhibit numerous attractive properties which meet these demands. These properties include high melting point, low density, high specific elastic modulus, good oxidation and burn resistance, and high specific strength up to application temperatures of 700 to 800°C. Thus, current -TiAl based alloys outperform advanced Ti-based alloys and have the potential to replace heavy Ni-based superalloys.
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Wang, Shaopeng, Lian Zhou, Changjiu Li, Zhengxian Li, Hongzhan Li, and Lijing Yang. "Micrographic Properties of Composite Coatings Prepared on TA2 Substrate by Hot-Dipping in Al–Si Alloy and Using Micro-Arc Oxidation Technologies (MAO)." Coatings 10, no. 4 (April 10, 2020): 374. http://dx.doi.org/10.3390/coatings10040374.
Повний текст джерелаАнотація:
A composite coating composed of intermetallic compounds, Al–Si alloys, and an oxide ceramic layer was prepared on TA2 substrate by hot-dipping Al–Si alloy and micro-arc oxidation (MAO) methods. The microstructure and composition distribution of the resulting hot-dipped Al–Si alloy layer and MAO-caused ceramic layer were studied by scanning electron microscope (SEM) and energy dispersive spectrum (EDS). In addition, the phase composition of the diffusion layer obtained by the Al–Si alloy hot-dipping procedure was investigated by electron backscattered diffraction (EBSD), and the phase structure of the MAO-treated layer was studied by X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS). The MAO method can make the hot-dipped Al–Si alloy layer in-situ oxidized to form a ceramic layer. Finally, a three-layer composite coating composed of a diffusion layer formed by the Ti–Al–Si interdiffusion, an Al–Si alloy layer and a ceramic layer was prepared on TA2 substrate. Compared with TA2 substrate, the TA2 sample with a three-layer composite coating has larger friction coefficient and less abrasion loss. The three-layer composite coating can significantly improve the wear resistance of TA2. A technical composite method was developed to the low cost in-situ growth of alumina-based ceramic wear-resistant coatings on TA2 substrate.
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Mitra, Rahul. "Oxidation Behavior of Silicides." Diffusion Foundations 21 (March 2019): 127–56. http://dx.doi.org/10.4028/www.scientific.net/df.21.127.
Повний текст джерелаАнотація:
The oxidation behavior of Mo, Nb, and Ti-silicides has received significant attention in past few decades for their potential to be used as high temperature structural materials. These Si-bearing intermetallic alloys have the ability to form an oxide scale containing SiO2, which is protective if formed as a continuous and impervious layer, so that the ingress of oxygen from atmosphere to the underneath alloy is restricted. To form a continuous and stable SiO2scale, it is important to have sufficient activity of Si along with thermodynamic and kinetic conditions favoring its growth in comparison to that of oxides of other alloying elements. MoSi2has superior oxidation resistance compared to that of Mo3Si or Mo5Si3, because of its higher Si content. Furthermore, a continuous film of SiO2is able to form at temperatures in the range of 800-1700oC on MoSi2due to vaporization of MoO3, but not on NbSi2or TiSi2due to competitive growth of Nb2O5or TiO2, respectively. During past two decades, a significant effort has been devoted to development of Mo-Si-B alloys containing Mo-rich solid solution, Mo3Si and Mo5SiB2as constituent phases, due to their ability to form a protective borosilicate scale. The presence of B2O3contributes to fluidity of borosilicate scale, thereby contributing to closure of porosities. Efforts have been also made to develop multicomponent Nb-silicide based alloys with optimum combination of mechanical properties and high temperature oxidation resistance with limited success. There have been efforts to develop silicide based coatings for protection oxidation for Mo-rich Mo-Si-B alloys and Nb-Si based ternary or multicomponent alloys with inadequate oxidation resistance. Oxidation behavior of selected silicides with potential for structural application, along with mechanisms for protection against oxidation has been reviewed and discussed.
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Moszner, Peng, Suutala, Jasnau, Damani, and Palm. "Application of Iron Aluminides in the Combustion Chamber of Large Bore 2-Stroke Marine Engines." Metals 9, no. 8 (July 31, 2019): 847. http://dx.doi.org/10.3390/met9080847.
Повний текст джерелаАнотація:
Iron aluminides possess a unique combination of properties such as attractive corrosion resistance in hot gas and wet chemical environments, a favorable strength to weight ratio, low costs of alloying elements, and they can be processed by conventional methods. For the current study, a promising iron aluminide (Fe-Al-Mo-Ti-B) was employed, which shows the potential to replace costly heat resistant steels or expensive Ni-based alloys for components in large bore two-stroke marine engines. The prechamber, an integral part of the combustion system of dual fuel two-stroke marine engines, which must withstand harsh conditions, was selected as the component. Prototypes made of the novel iron aluminide were manufactured via investment casting and hot isostatic pressing using powder of the intermetallic alloy. The high temperature oxidation behavior, the wet corrosion resistance in acid media, and the mechanical properties up to 700 °C were evaluated. A prototype of the prechamber was tested on a large bore two-stroke dual fuel test engine and post analysis of the tested component was performed. The results show that the employed iron aluminide alloy could be an economic alternative to the currently used Ni-based alloy.
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Yakovlev, Igor, Daniil Astakhov, Sergey Zambalov, Nikita Pichugin, and Anatoly Maznoy. "Oxidation-Affected Erosion of Porous Ni-Al Intermetallic Alloy in Combustion Applications: Pore-Scale Simulation." Metals 13, no. 2 (January 30, 2023): 277. http://dx.doi.org/10.3390/met13020277.
Повний текст джерелаАнотація:
Advanced high-temperature oxidation resistance is a crucial characteristic of metallic materials in porous burners. Extreme combustion conditions could lead to oxidation-affected erosion of porous media at a long-time period of burner operation. In this paper, we numerically simulated oxide scale growth at a porous radiant burner fabricated by Ni-Al intermetallic alloy using the combustion synthesis method, focusing on the structure degradation caused by periodic oxide scale spallation. A three-dimensional geometrical model of a porous intermetallic scaffold was obtained by scanning the porous burner using the X-ray CT technique. The surface erosion was modeled by the surface reconstruction based on calculated values of spalled oxide layer thickness. The simulation revealed that the submerged flame results in non-uniform distribution of the temperature at the solid surface. Such non-isothermal conditions lead to a two-times thicker oxide scale at the external surface of the burner. Thin struts of the intermetallic scaffold are prone to oxidation-affected erosion first, which forms discontinues and further fragmentation. The porous scaffold could lose about 50% of initial weight before fragmentation under conditions with intense oxide spallation. In such large structural degradation, the average flow velocity could reduce by a factor of 3, leading to changing of flame stabilization region.
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Srigiofun, Pajaree, Panyawat Wangyao, Gobboon Lothongkum, and Ekasit Nisaratanaporn. "Effect of Al and Ti Additions in Cast Nickel Base Alloy, Grade Hastelloy X by Arc Melting Process on Microstructures and Oxidation Behavior at 900°C and 1000°C." Applied Mechanics and Materials 548-549 (April 2014): 274–79. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.274.
Повний текст джерелаАнотація:
The nickel base alloy, grade Hastelloy X was modified by Aluminum and Titanium additions by means of vacuum arc melting process in order to improve microstructural characteristics and oxidation resistance. The arc melted Hastelloy X was added Aluminum and Titanium each for 2%, 4% and 6% by weight. Then all specimens were performed with heat treatment, which consists of solutioning treatment at 1125°C for 24 hours and precipitation aging at temperatures of 760°C, 800°C and 845°C for 24 hours. Both aluminum and titanium additions resulted in network intermetalic phase formation, namely, σ-phase, throughout the matrix. Furthermore, the addition of both elements provided the better oxidation resistance for the alloys.
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Choi, Jee Hoon, and Dong Bok Lee. "High Temperature Corrosion of Al3Ti-Cr Intermetallics in SO2 Atmosphere." Advanced Materials Research 15-17 (February 2006): 398–403. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.398.
Повний текст джерелаАнотація:
L12-type Al65.5Ti24.4Cr10.1 alloys were prepared by induction melting followed by thermomechanical treatment. Corrosion tests were performed between 1173 and 1373 K in a flowing Ar-1% SO2 atmosphere for up to 150 hr. The corrosion proceeded mainly via the oxidation reaction. The oxide scale was primarily composed of Al2O3, together with a small amount of TiO2 that appeared mainly in the lower part of the oxide scale during the latter stages of corrosion. The formation of the highly stoichiometric, slowly growing alumina scale on the surface significantly improved the corrosion resistance of the alloys. Neither internal corrosion products nor sulfides were detected.
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Dyl, Tomasz Cyryl, Robert Starosta, and Robert Skoblik. "Effect of the Unit Pressure on the Selection Parameters of Intermetallic Coatings NiAl and Ni3Al after Plastic Working." Solid State Phenomena 165 (June 2010): 19–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.165.19.
Повний текст джерелаАнотація:
Modern materials on intermetallic matrix are in the scope of research of many scientific – research centers in Poland [1]. Intermetallic systematic alloys containing aluminium have high resistance to oxidation, abrasive corrosion and fatigue as well as heat resistance. That is why they are applied in the production of machine parts used in hard service conditions (internal combustion turbine blades, exhaust valves, turbo-blower rotors) [2]. Intermetallic coatings can be obtained by means of plasma spraying. Thermal spraying technology is widely used due to the possibility of increasing the service properties in surface layers (strength property, tribological, anti-corrosive and decorative property) as well as coating application on machine parts elements, on tools for plastic working (forging moulds busters, piston rods, gear wheels teeth, crank journals, valve seats, and combustion engine cylinders) [3, 4]. NiAl and Ni3Al coatings are characterized by high fatigue resistance, heat resistance and considerable corrosion resistance [5]. Coatings obtained by thermal spraying have high surface roughness. Thus, subsequent plastic treatment is advisable for plasma-sprayed intermetallic coatings. Therefore it is vital to define to what extent the change of unit pressure will influence reduction of surface roughness of intermetallic coatings. For this purpose experimental upsetting research was carried out on C45 steel samples having NiAl and Ni3Al coatings for the following unit pressures p = 500 MPa, p = 800 MPa, p = 1100 MPa.
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Jabłońska, Magdalena, Dariusz Kuc, and Iwona Bednarczyk. "Influence of Deformation Parameters on the Structure in Selected Intermetallic from Al-Fe Diagram." Solid State Phenomena 212 (December 2013): 63–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.212.63.
Повний текст джерелаАнотація:
Department of Materials Science at Silesian University of Technology since 10 years conducts researches to learn about the structural phenomena which occur during hot plastic treatment which are aimed at elaboration of a technology of heat and plastic treatment of selected alloys from Al-Fe diagram. The iron aluminides have been among the most widely studied intermetallics because their low cost, low density, good wear oxidation and corrosion resistance, to create wide prospects for their industrial applications, for components of machines working at a high temperature and in corrosive environment. The problem limiting their application is low plasticity and brittle cracking susceptibility. Consequently, the research of intermetallic-phase based alloys focuses on their plasticity. For the development of thermo-plastic treatment technology, it is necessary to determine internal variables describing the structure of an alloys being deformed is the inhomogeneity, grain size, as well as the grains misorientation angles and texture. The paper presents the course of structural changes of Fe-38Al with Zr, B Mo and C additions under the influence of hot plastic deformation with application of a few different temperatures of the process with given speed of deformation. For the structure and substructure investigations were used a light microscopy and transmission electron microscopy.
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Bondarenko, Yu A., M. Yu Kolodyazhnyy, and V. A. V. A. "Creation of high-temperature heat-resistant alloys based on refractory matrices and natural composites." Perspektivnye Materialy 2 (2021): 5–15. http://dx.doi.org/10.30791/1028-978x-2021-2-5-16.
Повний текст джерелаАнотація:
The scientific, technical and technological aspects in the field of creating new high-temperature materials for the hot tract parts of gas turbine engines (GTE) with operating temperatures exceeding those existing in the GTE are considered. Investigated more refractory metal materials to create new high-temperature alloys used in the manufacture of working and nozzle blades and other parts of promising gas turbine engines based on Co – Cr, Pt – Al, Nb – Si, Mo – Si – B systems. In Co – Cr alloys, heat resistance is mainly ensured by hardening the Co matrix, including dispersed precipitates of the carbide phase (TaC) and the boride phase Cr2B. In alloys of the Pt – Al system, due to the doping of Cr, Al, Ti, Re ... and precipitates of the coherently embedded Pt3Al phase. In eutectic alloys of the Nb-Si system, this is due to complex hardening of the Nb solid solution and Nb5Si3 silicide, as well as the natural compositional structure. In Mo – Si – B alloys, high strength is achieved by doping a-Mo solid solution and the formation of intermetallic phases Mo3Si, Mo5SiB2, carbides Mo2C, TiC. Compositions were selected, analysis of their smelting methods was carried out, including directed crystallization, which provides a natural compositional structure, mechanical properties at room and high temperatures, oxidation resistance were evaluated, structural features were investigated, information was provided on technological equipment and the possibility of obtaining parts in various ways. It is shown that, depending on the composition of the selected matrix, the working temperature of heat-resistant alloys can increase to 1300 – 1500 °C, which significantly exceeds the existing nickel heat-resistant alloys. It is concluded that the materials under study are promising for use in aircraft engine building and the aerospace industry.
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Amal Rebin, A. X., S. Kumaran, and T. Srinivasa Rao. "Influence of Scandium on Magnesium and its Structure-Property Correlation." Materials Science Forum 710 (January 2012): 132–36. http://dx.doi.org/10.4028/www.scientific.net/msf.710.132.
Повний текст джерелаАнотація:
Magnesium alloys are the most demanded lightweight structural materials for different engineering applications such as aerospace, automobile, electronics, etc. However, the high temperature properties of Mg alloys are not comparable with its competitor, the Al alloys. Mg alloys are not recommended beyond 120°C due to their poor creep and oxidation resistance. In order to improve the high temperature properties of the magnesium alloys, rare earth containing Mg alloys were developed. Among these alloys, Mg-Sc alloys were found to be very interesting which exhibits better high temperature properties. In the present work, magnesium-scandium alloy was fabricated through liquid metallurgy route under inert cover. The alloy was characterized by optical microscopy, X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA) and hardness testing. The microstructural analysis reveals the α-Mg phase and the distribution of fine Mg-Sc intermetallic. It is observed from the DTA that the melting point of the base alloy has got enhanced by the addition of Sc. There is also an appreciable improvement in the hardness by the addition of Sc.
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Carro, G., J. E. Wittig, E. A. Kenik, and W. F. Flanagan. "Precipitation of chromium borides in annealed nickel aluminides." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 948–49. http://dx.doi.org/10.1017/s0424820100177878.
Повний текст джерелаАнотація:
Alloys based on the intermetallic phase, Ni3Al, are a class of materials noted for superior elevated temperature mechanical properties and oxidation resistance. Boron has been shown to increase ductility in these alloys and chromium additions to boron-doped nickel aluminide alloys have been reported to improve the high temperature properties by reducing dynamic embrittlement in oxidizing environments. However, a potential problem with these Ni-Al-Cr-B alloys is the depletion of chromium and boron at grain boundaries from chromium boride precipitation.Two alloys were investigated for elevated temperature chromium boride precipitation. The first, IC-218, has the composition (at%): 16.4 Al, 8.0 Cr, 0.4 Zr, 0.1 B, Ni bal., and the second, OR3B contains 15.0 Al, 10.0 Cr, 0.1 B, Ni bal.. Samples of both alloys were rapidly solidified into circular foils, 0.25 mm thick, by splat quenching between two copper plates. Also, cold rolled and recrystallized sheet, 3 mm thick, of IC-218 was used for comparison.
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Dudziak, Tomasz Pawel, Hailiang Du, and Prasanta Datta. "Long exposure test in air, conducted on super-lattice coatings at 850°C for 4,000 hours." Anti-Corrosion Methods and Materials 62, no. 6 (November 2, 2015): 394–99. http://dx.doi.org/10.1108/acmm-03-2014-1366.
Повний текст джерелаАнотація:
Purpose – The purpose of this study is to investigate the high-temperature behavior of newly developed high-impulse power magnetron sputtering system (HIPIMS) coatings and compare them to the standard TiAlCr system deposited on to a Ti–Al intermetallic alloy. The corrosion test was performed in air for 4,000 hours at 850°C. Design/methodology/approach – In this study, air oxidation test was performed at high temperature. Design and methodology is described in detail in the methodology section in the submitted manuscript. The test was carried out by discontinuous exposure of the three different systems produced by different deposition technique. The exposed samples were investigated using scanning electron microscope coupled with energy dispersive X-ray spectroscopy. The exposed samples were investigated from the surface and cross-sections. Findings – The performed study shows that HIPIMS coatings had a much better oxidation resistance at a high temperature than that offered by the standard physical vapor deposition (PVD) system. HIPIMS costing developed Al–Cr oxide on the surface; however, cracks and detachments were found at the interface between the coating and the substrate. TiAlCr coating spalled off from the material due to the critical thickness reached; moreover, high brittleness and lack of adherence were found. Due to poor oxidation resistance, TiAlCr coating was discarded from the test after 3,000 hours of exposure. Originality/value – The work performed in this study was designed for 4,000 hours oxidation at 850°C. The long-term exposures are not commonly met in the research work due to the cost and time. The work clearly shows differences between new type of coatings and standard PVD system applied on TiAl lightweight alloy.
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Buluc, Gheorghe, Iulia Florea, Oana Bălţătescu, Costel Roman, and Ioan Carcea. "Microstructure and Mechanical Properties of FeNiCrCuAl High Entropy Alloys." Advanced Materials Research 1036 (October 2014): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amr.1036.101.
Повний текст джерелаАнотація:
This paper presents the microstructure and the mechanical properties of FeNiCrCuAl high entropy alloys. The microstructure and mechanical properties of the annealed FeNiCrCuAl high entropy alloys were investigated using scanning electron microscopy, and X-ray diffraction. High entropy alloys have been known as a new type of materials and have been defined as having five or more principal elements, each one having a concentration between 5 and 35 at.%. Previous researches show that HEAs can be processed to form simple solid solution structures instead of intermetallics and other complicated compounds. This phenomenon is commonly attributed to the high configurational entropy in the solid solution state of HEAs. Furthermore, HEAs have also exhibited interesting properties such as high hardness and high strength, good thermal stability outstanding wear and oxidation resistance which offer great potential for engineering applications. The HEA systems explored in the past decade show that metallic elements are the most commonly used, e.g. Al, Cr, Fe, Co, Ni, Cu,Ti, etc. A wide range of HEAs exhibit high hardness, high strength, distinctive electrical and magnetic properties, high-temperature softening resistance, as well as favorable combination of compression strength and ductility. This combination of properties and the particular structures of HEAs are attractive for a number of potential engineering applications.
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Fukumoto, Michihisa, Ryou Matsui, Motoi Hara, and Toshio Narita. "Coating of Ni-Al Intermetallic Compound on Nb by Electrodeposition Treatment and High Temperature Oxidation Resistance." Journal of the Japan Institute of Metals 68, no. 8 (2004): 548–51. http://dx.doi.org/10.2320/jinstmet.68.548.
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Braun, Reinhold, Klemens Kelm, Maik Fröhlich та Christoph Leyens. "Oxidation resistance of γ-TiAl based alloy Ti–45Al–8Nb coated with intermetallic Ti–Al–Cr–Y layers and EB-PVD zirconia topcoats at 950°C in air". Surface and Coatings Technology 222 (травень 2013): 128–34. http://dx.doi.org/10.1016/j.surfcoat.2013.02.014.
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Kopyciński, D., E. Guzik, R. Gilewski, A. Szczęsny, and J. Dorula. "Analysis of Structure and Abrasion Resistance of the Metal Composite Based on an Intermetallic FeAl Phase with VC and TiC Precipitates." Archives of Foundry Engineering 13, no. 3 (September 1, 2013): 51–54. http://dx.doi.org/10.2478/afe-2013-0058.
Повний текст джерелаАнотація:
Abstract Metal alloys with matrix based on an Fe-Al system are generally considered materials for high-temperature applications. Their main advantages are compact crystallographic structure, long-range ordering and structural stability at high temperatures. These materials are based on an intermetallic phase of FeAl or Fe3Al, which is stable in the range from room temperature up to the melting point of 1240°C. Their application at high temperatures is also beneficial because of the low cost of production, very good resistance to oxidation and corrosion, and high mechanical strength. The casting alloy the structure of which includes the FeAl phase is, among others, highaluminium cast iron. This study has been devoted to the determination of the effect of vanadium and titanium on the transformation of the high-aluminium cast iron structure into an in-situ FeAl-VC composite.
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Khieokae, Marut, Ratchawit Hanamornroongruang, Ratachris Ramasoot, Akadej Taechakaesaree, Paphawit Ngamchaliew, and Luangvaranunt Tachai. "Diffusion Coefficient of Nickel in Ni2Al3 Intermetallic Compound." Advanced Materials Research 1025-1026 (September 2014): 731–36. http://dx.doi.org/10.4028/www.scientific.net/amr.1025-1026.731.
Повний текст джерелаАнотація:
Nickel alloys have been widely used for high temperature applications such as gas turbine engine, turbine blade and many high temperature resistance components. Aluminizing is one of effective to increase oxidation resistant of nickel alloys by forming nickel aluminide compounds on nickel surface. Nickel aluminide is formed by the diffusion mechanism. This research aims to study the diffusion behavior of nickel in Ni2Al3compound. The diffusion coefficient is determined using Ni/Al diffusion couple forming Ni2Al3and NiAl3phases. The temperatures under study are 873, 973, and 1073 K, which are at above and below melting point of aluminum. Determination of diffusion coefficient of Ni in Ni2Al3is from mass balance concept: flux difference at interphase causes accumulation of atoms in compound layer, which as be derived as: dxαβ/dt = [1/(nβ-nα)] * [Dα*(dnα/dx) - Dβ*(dnβ/dx)] From this equation, diffusion coefficient of Ni in Ni2Al3at 873 and 1073 K are calculated as 6.243×10-11and 6.82×10-9m2/s, respectively. From Arrhenius equation of diffusivity, D = Doexp (-Q/RT), the activation energy for diffusion of nickel in Ni2Al3is found to be 183 kJ/mol. The result obtained in this research is of great use in controlling aluminizing process.
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Ezirmik, Kadri Vefa. "Corrosion and High Temperature Oxidation Behavior of Structural Steels Coated with Aluminum Alloys." BEN Vol:2 Issue:3 2021 2, no. 3 (April 2, 2021): 22–26. http://dx.doi.org/10.36937/ben.2021.003.005.
Повний текст джерелаАнотація:
Structural steels are among the most widely used materials in today's industry. Various surface coating processes are used to protect structural steels from corrosion in atmospheric or aggressive environments. The most commonly used method is the galvanizing process based on forming zinc coating on the steel surface by using the hot dip method. Zinc coatings are insufficient to protect against corrosion, especially in chlorinated environments. Aluminum and its alloys stand out as an alternative material group to zinc in chlorinated environments. In this study, aluminum and aluminum alloy coatings, which are thought to be an alternative to zinc coating, were coated on the structural steel surface using the hot dip method. To examine how different aluminum alloys affect the corrosion and high-temperature oxidation properties of steels, nearly pure AA1050, high Cu content AA2024, and high Mg content AA5083 alloys were coated on structural steels. The coating process was carried out by dipping the structural steels into molten aluminum baths kept at a constant temperature of 700°C for 1, 3, and 5 minutes. The optimum adhesion and surface properties were obtained from dipping time for 3 minutes. The properties of coatings and intermetallic structures formed at the coating-steel interface were examined using an optical microscope, X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), and Energy Scattering Spectroscopy (EDS) systems. To examine the high-temperature oxidation properties of the coatings, the coated samples were oxidized for 24 hours at 750°C under open-air conditions, and the changes in weight were investigated. Immersion corrosion tests were performed in 3.5% NaCl solution, and corrosion losses and degradation patterns were investigated. As a result of the studies, it has been determined that the Al coatings produced by the hot dip process significantly increase the oxidation and corrosion resistance of the structural steels.
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Huy, Tran Duc, Nguyen Hong Hai, and Keiichi N. Ishihihara. "Synthesis In Situ Composite TiAl-Based with Particulate Al2O3 Reinforcement by Powder Metallurgy Route." Advanced Materials Research 858 (November 2013): 159–63. http://dx.doi.org/10.4028/www.scientific.net/amr.858.159.
Повний текст джерелаАнотація:
A major effort has been made over last 20 or so years to introduce TiAl-based alloys into the market-place as engineering component. Recently, titanium aluminide based composites are competitive candidate for aerospace use due to the favorable properties of matrix material, such as low density, high specific strength and relative good properties at elevate temperature [1-4]. The amount of aluminum in titanium alloys exceeds that used in conventional alloys and can range from 10 to 48at%. This concentration of aluminum allows the formation of anin-situalumina reinforcement which is responsible for the excellent oxidation, sulfidation and carburization resistance at temperatures of 1000°C and higher. However, their brittleness and rapid crack growth rate at low to intermediate temperature hinders their application/3/. Nevertheless, nanostructure of monolithic TiAl is unstable at elevate temperatures which deteriorate the high temperature properties. In order to improve the high temperature strength of intermetallic, ceramic particles can be utilized as reinforcements [4, 5]. Recently, in-situ techniques have been utilized to fabricate TiAl-Al2O3composite through displacement reaction between TiO2and Al in planetary ball milling and subsequence heat treatment. The knowledge of reaction characteristic in the Al-TiO2system is great importance to optimize the processing/4, 6/. The chemical compatibility with the iron aluminide matrix at temperature above 1000°C is an important factor for the selection of reinforcements because extreme interfacial reaction during processing results in the degradation of mechanical properties [3, 4].
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Martins, Norberto, Ana Paula Silva, Gilmar Cordeiro da Silva, Ítalo Bruno dos Santos, Carlos Eduardo dos Santos, Fernanda Troysi, and Pedro Brito. "Characterization of Iron Aluminide Diffusion Coatings Obtained after Friction Surfacing." Metals 13, no. 3 (February 23, 2023): 461. http://dx.doi.org/10.3390/met13030461.
Повний текст джерелаАнотація:
Iron aluminides are considered as candidate materials for high temperature applications for their excellent high temperature corrosion and oxidation resistance. In the present work, iron-aluminide coatings were developed by friction surfacing (6351 aluminum alloy deposited on a low-carbon steel substrate) followed by a diffusion heat treatment. The initial coatings were found to be geometrically homogenous and adhered well to the steel substrate. The heat treatment process was carried out at 550 °C for 48, 72 and 96 h and the resulting coatings were characterized in terms of microstructure, chemical composition, hardness distribution and phase composition. After heat treatment, the coating/substrate interface morphology was modified and presented patterns typical of Fe-Al intermetallic formation, as well as a substantial increase in hardness (>900 HV) relative to the initial as-deposited condition. With the diffusion treatment, initially Fe2Al5 was found to develop in the coatings, which was converted into FeAl2 after longer exposures.