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Journal articles on the topic 'NiAl-Al2O3'

Author: Grafiati

Published: 14 July 2022

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1

Hwang, Chii-Shyang, and Tien-Jui Liu. "Microstructure and mechanical properties of NiAl/Al2O3 composites." Journal of Materials Research 14, no. 1 (January 1999): 75–82. http://dx.doi.org/10.1557/jmr.1999.0013.

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To improve mechanical properties of NiAl, a method for making NiAl matrix composites containing oxide ceramics is introduced. The method involves oxidation of NiAl powder in air to form a thin and uniform oxide scale, mainly Al2O3, on the NiAl particles. The Al2O3 contents increase with increasing oxidation temperature. The NiAl/Al2O3 composites are then formed by hot-pressing the oxidized NiAl powder under vacuum atmosphere. Al2O3 inhibits the grain growth of NiAl during the hot-pressing. The residual stress and the Ni-rich NiAl composition exist in the hot-pressed NiAl/Al2O3 composites. Strength and toughness data on NiAl/Al2O3 composites indicate that the use of oxidation of NiAl powder is a viable technique for improving these properties over that of monolithic NiAl.

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2

Davies, I. J., G. Pezzotti, A. Bellosi, D. Sciti, and S. Guicciardi. "Mechanical Behaviour of Nickel Aluminide Reinforced Alumina (AL2O3-NiAl) Composites." Advanced Composites Letters 11, no. 6 (November 2002): 096369350201100. http://dx.doi.org/10.1177/096369350201100601.

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The microstructure and mechanical properties of hot-pressed alumina (Al2O3) matrix composites containing 20, 35, or 50 vol% of nickel aluminide (NiAl) were investigated. The mean Al2O3 grain size was found to decrease from approximately 2.0 μm (monolithic Al2O3) to 1.0 μm for the composite containing 50 vol% NiAl. Composite flexural strength values were lower than both the monolithic Al2O3 and NiAl and attributed to the weakly bonded NiAl particles acting as flaw origins. In contrast to this, the fracture toughness increased with NiAl volume fraction to a maximum of 4.90 MPa·m1/2, thus confirming the toughening effect of NiAl addition on Al2O3 ceramics, with the slope of the rising R-curve for the composite being approximately 8 times that of monolithic Al2O3.

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3

Konopka, Katarzyna, Marek Krasnowski, Justyna Zygmuntowicz, Konrad Cymerman, Marcin Wachowski, and Paulina Piotrkiewicz. "Characterization of Al2O3 Samples and NiAl–Al2O3 Composite Consolidated by Pulse Plasma Sintering." Materials 14, no. 12 (June 19, 2021): 3398. http://dx.doi.org/10.3390/ma14123398.

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The paper describes an investigation of Al2O3 samples and NiAl–Al2O3 composites consolidated by pulse plasma sintering (PPS). In the experiment, several methods were used to determine the properties and microstructure of the raw Al2O3 powder, NiAl–Al2O3 powder after mechanical alloying, and samples obtained via the PPS. The microstructural investigation of the alumina and composite properties involves scanning electron microscopy (SEM) analysis and X-ray diffraction (XRD). The relative densities were investigated with helium pycnometer and Archimedes method measurements. Microhardness analysis with fracture toughness (KIC) measures was applied to estimate the mechanical properties of the investigated materials. Using the PPS technique allows the production of bulk Al2O3 samples and intermetallic ceramic composites from the NiAl–Al2O3 system. To produce by PPS method the NiAl–Al2O3 bulk materials initially, the composite powder NiAl–Al2O3 was obtained by mechanical alloying. As initial powders, Ni, Al, and Al2O3 were used. After the PPS process, the final composite materials consist of two phases: Al2O3 located within the NiAl matrix. The intermetallic ceramic composites have relative densities: for composites with 10 wt.% Al2O3 97.9% and samples containing 20 wt.% Al2O3 close to 100%. The hardness of both composites is equal to 5.8 GPa. Moreover, after PPS consolidation, NiAl–Al2O3 composites were characterized by high plasticity. The presented results are promising for the subsequent study of consolidation composite NiAl–Al2O3 powder with various initial contributions of ceramics (Al2O3) and a mixture of intermetallic–ceramic composite powders with the addition of ceramics to fabricate composites with complex microstructures and properties. In composites with complex microstructures that belong to the new class of composites, in particular, the synergistic effect of various mechanisms of improving the fracture toughness will be operated.

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4

Afandi, N. F., Abreeza Manap, Halina Misran, S. Z. Othman, and N. I. M. Pauzi. "Characterizations of NiAl-Al₂O₃ Produced Using Gel Combustion Synthesis Method." Applied Mechanics and Materials 761 (May 2015): 457–61. http://dx.doi.org/10.4028/www.scientific.net/amm.761.457.

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NiAl is widely used for elevated temperature application because it gives better properties, especially in the gas turbine application. This study was done in order to investigate the effects of calcination temperature on NiAl and α-Al2O3 formation using gel combustion synthesis method. This method used fatty alcohol and fatty acid ester for producing NiAl powders. X-Ray diffraction patterns of calcined samples exhibited NiAl and α-Al2O3 at temperature 1050°C. Therefore, nanostructured NiAl-α- Al2O3 can be successfully produced with the gel combustion method using less expensive and more environmental friendly fatty alcohol and fatty acid ester as fuels.

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5

Zhang, X. J., and Yan Niu. "Oxidation of Four NiAl-Ag Alloys at 900°C in 1 Atm O₂." Materials Science Forum 475-479 (January 2005): 775–78. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.775.

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Small amounts of silver have been added to the intermetallic compound β-NiAl for the purpose of improving its mechanical properties. Four ternary NiAl-Ag alloys NiAl-0.5Ag, NiAl-1Ag, NiAl-5Ag and NiAl-10Ag (at.%), and an Ag-free β-NiAl have been oxidized at 900oC for 24 h in 1 atm O2 to study the effect of the presence of silver on the oxidation of β-NiAl. The kinetics of all the alloys were generally composed of two main parabolic stages with slightly larger parabolic rate constants for the second stage, except for NiAl-10Ag, which has an instantaneous parabolic rate constant decreasing with time. A continuous external layer of Al2O3 formed on all the alloys. In particular, the scales formed on NiAl-5Ag and NiAl-10Ag contained a thin and discontinuous layer of silver at the alloy/Al2O3 interface. Furthermore, NiAl-10Ag formed also isolated Ag particles or even a discontinuous Ag layer occasionally surmounting the Al2O3 scale. The addition of minor amounts of silver does not affect significantly the oxidation of β-NiAl, because silver is essentially present as a second phase due to its very small solubility in this intermetallic compound.

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6

Zygmuntowicz, Justyna, Katarzyna Konopka, Marek Krasnowski, Paulina Piotrkiewicz, Jan Bolek, Marcin Wachowski, Radosław Żurowski, and Mikołaj Szafran. "Characterization of Al2O3 Matrix Composites Fabricated via the Slip Casting Method Using NiAl-Al2O3 Composite Powder." Materials 15, no. 8 (April 16, 2022): 2920. http://dx.doi.org/10.3390/ma15082920.

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This work aimed to characterize Al2O3 matrix composites fabricated by the slip casting method using NiAl-Al2O3 composite powder as the initial powder. The composite powder, consisting of NiAl + 30 wt.% Al2O3, was obtained by mechanical alloying of Al2O3, Al, and Ni powders. The composite powder was added to the Al2O3 powder to prepare the final powder for the slip casting method. The stained composite samples presented high density. EDX and XRD analyses showed that the sintering process of the samples in an air atmosphere caused the formation of the NiAl2O4 spinel phase. Finally, the phase composition of the composites changed from the initial phases of Al2O3 and NiAl to Al2O3, Ni, and NiAl2O4. However, in the area of Ni, fine Al2O3 particles remaining from the initial composite powder were visible. It can be concluded that after slip casting, after starting with Al2O3 and the composite powder (NiAl-Al2O3) and upon sintering in air, ceramic matrix composites with Ni and NiAl2O4 phases, complex structures, high-quality sintered samples, and favorable mechanical properties were obtained.

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7

Chmielewski, M., S. Nosewicz, K. Pietrzak, J. Rojek, A. Strojny-Nędza, S. Mackiewicz, and J. Dutkiewicz. "Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites." Journal of Materials Engineering and Performance 23, no. 11 (August 12, 2014): 3875–86. http://dx.doi.org/10.1007/s11665-014-1189-z.

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8

Konopka, Katarzyna, Justyna Zygmuntowicz, Marek Krasnowski, Konrad Cymerman, Marcin Wachowski, and Paulina Piotrkiewicz. "Pulse Plasma Sintering of NiAl-Al2O3 Composite Powder Produced by Mechanical Alloying with Contribution of Nanometric Al2O3 Powder." Materials 15, no. 2 (January 6, 2022): 407. http://dx.doi.org/10.3390/ma15020407.

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NiAl-Al2O3 composites, fabricated from the prepared composite powders by mechanical alloying and then consolidated by pulse plasma sintering, were presented. The use of nanometric alumina powder for reinforcement of a synthetized intermetallic matrix was the innovative concept of this work. Moreover, this is the first reported attempt to use the Pulse Plasma Sintering (PPS) method to consolidate composite powder with the contribution of nanometric alumina powder. The composite powders consisting of the intermetallic phase NiAl and Al2O3 were prepared by mechanical alloying from powder mixtures containing Ni-50at.%Al with the contribution of 10 wt.% or 20 wt.% nanometric aluminum oxide. A nanocrystalline NiAl matrix was formed, with uniformly distributed Al2O3 inclusions as reinforcement. The PPS method successfully consolidated NiAl-Al2O3 composite powders with limited grain growth in the NiAl matrix. The appropriate sintering temperature for composite powder was selected based on analysis of the grain growth and hardness of Al2O3 subjected to PPS consolidation at various temperatures. As a result of these tests, sintering of the NiAl-Al2O3 powders was carried out at temperatures of 1200 °C, 1300 °C, and 1400 °C. The microstructure and properties of the initial powders, composite powders, and consolidated bulk composite materials were characterized by SEM, EDS, XRD, density, and hardness measurements. The hardness of the ultrafine-grained NiAl-Al2O3 composites obtained via PPS depends on the Al2O3 content in the composite, as well as the sintering temperature applied. The highest values of the hardness of the composites were obtained after sintering at the lowest temperature (1200 °C), reaching 7.2 ± 0.29 GPa and 8.4 ± 0.07 GPa for 10 wt.% Al2O3 and 20 wt.% Al2O3, respectively, and exceeding the hardness values reported in the literature. From a technological point of view, the possibility to use sintering temperatures as low as 1200 °C is crucial for the production of fully dense, ultrafine-grained composites with high hardness.

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9

Lee, W. Y., Y. W. Bae, and K. L. More. "Synthesis of functionally graded metal-ceramic microstructures by chemical vapor deposition." Journal of Materials Research 10, no. 12 (December 1995): 3000–3002. http://dx.doi.org/10.1557/jmr.1995.3000.

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A composite microstructure consisting of small α-Al2O3 particles dispersed in a β-NiAl coating matrix was synthesized by chemical vapor deposition (CVD). White the surface of a pure Ni substrate was being reacted with AlCl3 and H2 to form β-NiAl at a temperature of 1050 °C, the partial pressure of CO2 in the reactor was controlled via pulsing to nucleate and disperse 50 to 500 nm α-Al2O3 particles in the β-NiAl matrix. The relative amount of the α-Al2O3 phase increased with coating thickness as the rate of the β-NiAl formation decreased with time. These experimental observations suggest that the synthesis of a graded composite microstructure by the CVD method is feasible.

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10

Ramdan, Raden Dadan, Budi Prawara, and Rochim Suratman. "Thermal Oxidation of NiAl-Al₂O₃ Coated on Mild Carbon Steel." Advanced Materials Research 488-489 (March 2012): 437–41. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.437.

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Thermal oxidation is believed as an important phenomenon that naturally occurs on material subjected to elevated temperature such as NiAl-Al2O3 coated material. In the present study, thermal oxidation on this coated layer was prepared by heating processes of NiAl-Al2O3 coated on mild carbon steel. Deposition of NiAl-Al2O3 was performed by high-velocity oxy fuel (HVOF) process, whereas subsequent heating processes were performed at 3 different temperatures 600oC, 800oC and 1000oC. After the process, the effects of this thermal oxidation process on the phases formation, microstructure and qualitative toughness of thermally sprayed NiAl-Al2O3 coating were investigated. The results showed that significant amount of NiAl-Al2O3 phase was transformed into NiO phase by heating process at temperature higher than 800°C. In addition, decreasing of thickness of the coating layer was also found as the service temperature increases from 800 to 1000oC. Increasing of hardness was also observed as the heating temperature increases, which is predicted due to the formation of excessive oxide on the coating layer that in turn might impart the toughness of this layer. These conditions suggested that a careful determination of service temperature have to be taken in order to avoid excessive oxidation of the coating layer.

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11

Qi, Guo Quan, Feng Shou Shangguan, Li Neng Yang, Qiang Bai, and Gang Wu. "Microstructure and Mechanical Properties of Al₂O₃/NiAl In Situ Composites by Hot-Press-Aided Reaction Synthesis." Advanced Materials Research 581-582 (October 2012): 548–51. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.548.

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Al2O3/NiAl composites were successfully fabricated by hot-press-assisted exothermic dispersion method with elemental powder mixtures of Ni, Al, NiO. The content of Al2O3 on the microstructures and mechanical properties of Al2O3/NiAl composites has been characterized. The results show that the Vickers hardness, flexural strength and fracture toughness of the composites increase with increasing Al2O3 content. When the Al2O3 content is 15 wt %, the flexural strength and the fracture toughness peaked at 765 MPa and 9.67 MPa•m 1/2, respectively. The improvement of mechanical properties is associated with a more homogeneous and finer microstructure developed by addition of Al2O3.

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12

Vlad, A., A. Stierle, N. Kasper, H. Dosch, and M. Rühle. "In situ x-ray study of the γ- to α-Al2O3 phase transformation during atmospheric pressure oxidation of NiAl(110)." Journal of Materials Research 21, no. 12 (December 2006): 3047–57. http://dx.doi.org/10.1557/jmr.2006.0397.

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The oxidation in air of NiAl(110) was investigated in the temperature range from 870 °C–1200 °C by in situ x-ray diffraction and transmission electron microscopy. Oxidation at 870 °C and 1 bar oxygen leads to the formation of an epitaxial layer of γ-alumina showing an R30° orientation relationship with respect to the underlying substrate. At oxidation temperatures between 950 °C and 1025 °C, we observed a coexistence of epitaxial γ- and polycrystalline δ-Al2O3. The α-Al2O3 starts to form at 1025 °C and the complete transformation of metastable phases to the stable α-alumina phase takes place at 1100 °C. The fcc-hcp martensitic-like transformation of the initial γ-Al2O3 to epitaxial α-Al2O3 was observed. X-ray diffraction and cross-section transmission electron microscopy proved the existence of a continuous epitaxial α-Al2O3 layer between the substrate and the polycrystalline oxide scale, having a thickness of about 150 nm. The relative orientation relationship between the epitaxial alumina and the underlying substrate was found to be NiAl(110) || α-Al2O3 (0001) and [110] NiAl || [1120].

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13

Kalinski, D., M. Chmielewski, K. Pietrzak, and K. Choregiewicz. "An influence of mechanical mixing and hot-pressing on properties of NiAl/Al2O3 composite." Archives of Metallurgy and Materials 57, no. 3 (October 1, 2012): 695–702. http://dx.doi.org/10.2478/v10172-012-0075-7.

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Intermetallic phases of the Ni-Al type belong to the group of modern constructional materials which have numerous advantageous properties such as high melting temperature, low density, high resistance to high-temperature oxidation (to about 1200°C), high mechanical strength, high fatigue strength, and high tensile and compressive strength (also at elevated temperatures). Intermetallic compounds have however also drawbacks in that they are quite brittle at room temperature which makes their mechanical processing very difficult and restricts their application range. These drawbacks can be obviated by modifying their chemical composition. Improving the properties of NiAl-based materials can be achieved by creating the composite with the matrix made of an intermetallic phase NiAl reinforced with ceramic (Al2O3) particles. This paper is concerned with the mechanical and physical properties (bending strength, fracture toughness, hardness, and Young modulus) and also the microstructure of NiAl/Al2O3 composite. The composite materials were produced by the hot-pressed method using the NiAl/20%Al2O3 (vol.%) powder mixtures. The composite thus produced had a high density of about 99% of the theoretical value and a high bending strength. The bending strength of the NiAl/20vol.%Al2O3 composite was higher by about 80% (635 MPa) than that of the pure NiAl phase (345 MPa). The experiments included also the examination of the effect of the rotational speed of the mill and the duration of the mixing process upon the size and distribution of grains, the microstructure, and phase composition of the composite powder mixtures obtained.

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14

Orban, Radu L., Mariana Lucaci, Mario Rosso, and Marco Actis Grande. "NiAl Oxidation and Corrosion Resistant Coatings Obtained by Thermal Spraying." Advanced Materials Research 23 (October 2007): 273–76. http://dx.doi.org/10.4028/www.scientific.net/amr.23.273.

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There are investigated the possibilities to avoid or at least to reduce the Al2O3 scales formation on NiAl powder particles at its plasma spray deposition on steel substrates. The optimum processing parameters and the necessity to surround the plasma jet by an inert gas have been established. In appropriate processing conditions, the obtained coating layer is formed by flattened particles, welded together and to the substrate, proving their melting during spraying. It is dense and adherent, consisting of NiAl with only small Al2O3 inclusions, proving the NiAl stability preserving without decomposition or a notable oxidation, as premises of its desired functionality achievement.

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15

Tuan, Wei-Hsing, and Yu-Pan Pai. "Mechanical Properties of Al2O3-NiAl Composites." Journal of the American Ceramic Society 82, no. 6 (December 21, 2004): 1624–26. http://dx.doi.org/10.1111/j.1151-2916.1999.tb01974.x.

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16

Guo, Guan Hong, and He Guo Zhu. "Microwave Synthesis of the Composites (α-Al₂O₃+TiB₂)/NiAl from Al-TiO-B-Ni System." Advanced Materials Research 1120-1121 (July 2015): 604–7. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.604.

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NiAl matrix composites reinforced with a-Al2O3 and TiB2 were fabricated by microwave synthesis from Al-TiO2-B-Ni system. The reaction process and microstructures were analyzed by using differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM).The results showed that the ignition temperatures of the reaction heating by microwave and conventional method were approximately 556°C and 592°C respectively. Furthermore, the fabrication time by microwave synthesis was about several minutes, which was much shorter than two hours spent usually in conventional heating method. The a-Al2O3 phase aggregated at the trigonal grain boundary of the NiAl matrix, and the TiB2 phase distributed uniformly in the NiAl matrix.

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17

Wang, L., K. Xu, R. R. Bowman, and R. J. Arsenault. "Dislocations in continuous filament reinforced W/NiAl and Al2O3/NiAl composites." Metallurgical and Materials Transactions A 28, no. 12 (December 1997): 2755–61. http://dx.doi.org/10.1007/s11661-997-0032-7.

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18

Kaliński, Dariusz, Marcin Chmielewski, and Katarzyna Pietrzak. "Influence of Residual Thermal Stresses on the Properties of the NiAl Matrix Composites Reinforced with Ceramic Particles." Advances in Science and Technology 65 (October 2010): 21–26. http://dx.doi.org/10.4028/www.scientific.net/ast.65.21.

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One of the most important problems in both the fabrication and exploitation of ceramicmetal composites are residual thermal stresses. The paper presents the results of a numerical analysis (by the Finite Elements Method) of the stress state induced in the NiAl matrix composites reinforced with spherical particles of a ceramic phase (Al2O3, ZrO2, TiC), including examinations of the dependence of this stress state on the volumetric fraction of the ceramics (20 to 40vol.%). The stress state prevailing in this composite appeared to be complex. In all the samples, the stresses active in the ceramic regions were compressive whereas those active in the metal matrix were tensile in the circumferential direction and compressive in the radial direction. An increase of the ceramic volumetric fraction resulted in an increase of the tensile stresses in the NiAl matrix and a decrease of the compressive stresses in the ceramic particles. These theoretical results were verified experimentally by examining the properties of the NiAl-Al2O3, NiAl-ZrO2 and NiAl-TiC (20 and 30 vol.% fraction of the ceramics) composites produced by hot-pressing. The microstructure, density, and bending strength of these composites were examined, and the results are discussed in the paper.

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19

Samsudeen, Kasim, Al fatesh Ahmed, Mohammad Yahya, Aidid Ahmed, and Fakeeha Anis. "Effect of Calcination Temperature on Hydrogen Production via Ethanol Dry Reforming Over Ni/Al2O3 Catalyst." International Journal of Research in Science 4, no. 1 (March 23, 2018): 5. http://dx.doi.org/10.24178/ijrs.2018.4.1.05.

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Ni/Al2O3 catalysts were prepared by the wet-impregnation method and calcined at different temperatures (500°C, 600°C and 700°C) to obtain NiAl-1, NiAl-2 and NiAl-3 respectively. NiAl-1, NiAl-2, NiAl-3 represent catalysts calcined at 500°C, 600°C and 700°C respectively. The catalysts were characterized using different techniques, XRD, BET and TGA. XRD results revealed the presence of NiO phase on all the catalysts during calcination, however, the presence of spinel, NiAl2O4, was more pronounced on the catalyst calcined at 600°C (i.e. NiAl-2), indicating the existence of strong metal-support interaction. BET results showed that NiAl-1 has the highest surface area of about 190cm2/g. All the catalysts were tested for ethanol dry reforming in a tubular stainless steel fixed-bed reactor at 700°C and CO2/ethanol ratio of 3 under atmospheric pressure and were evaluated in terms of reactants conversion and selectivity of H2 to see the effect of the different calcination temperatures on the catalysts’ activities. Ethanol conversion was 100% for all the three catalysts and NiAl-2 has the highest CO2 conversion with an average value of about 57%. The three catalysts have almost the same performance in terms of H2 selectivity. The presence of multi-walled carbon nanofibers (MWCNFs) were confirmed on all the catalysts as revealed by the TGA result. The catalyst calcined at 600°C (i.e. NiAl-2) displayed the best relative catalytic activity

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20

Choo, Hahn, Philip Nash, and Marek Dollar. "Mechanical properties of NiAl–AlN–Al2O3 composites." Materials Science and Engineering: A 239-240 (December 1997): 464–71. http://dx.doi.org/10.1016/s0921-5093(97)00618-7.

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Dickey, E. C., B. A. Pint, K. B. Alexander, and I. G. Wright. "Oxidation behavior of platinum–aluminum alloys and the effect of Zr doping." Journal of Materials Research 14, no. 12 (December 1999): 4531–40. http://dx.doi.org/10.1557/jmr.1999.0615.

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The isothermal and cyclic oxidation behavior of PtAl and PtAl + Zr was studied followed by postoxidation microstructural and microchemical analyses. Their isothermal oxidation performance at 1200 °C was similar to that of NiAl and NiAl + Zr. In short (1-h) cycles, the cyclic oxidation resistance of undoped PtAl was found to be substantially better than NiAl. However, with longer (100-h) cycles, little improvement in the metal consumption rate was observed relative to NiAl. The addition of Zr to PtAl significantly improved cyclic oxidation performance in both short- and long-cycle tests. Spatially resolved energy dispersive spectroscopy indicated Zr segregation to both the metal–oxide interface and Al2O3 grain boundaries.

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22

Shirani-Bidabadi, Amir Reza, Ali Shokuhfar, Mohammad Hossein Enayati, and Mazda Biglari. "In Situ Fabrication and Characterization of (NiCr)Al-Al₂O₃ Nanocomposite by Mechanical Alloying." Journal of Nano Research 16 (January 2012): 21–27. http://dx.doi.org/10.4028/www.scientific.net/jnanor.16.21.

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In this research, the formation mechanisms of a (NiCr)Al-Al2O3 nanocomposite were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray difractometry (XRD) and the morphology and cross sectional microstructure of powder particles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The methodology involved mechanical alloying of NiO, Cr, and Al with molar ratios of 3:3:8. During mechanical alloying, NiO was first quickly reduced by aluminum atoms to produce NiAl nanocrystalline and Al2O3. Subsequently, and when a longer milling time was applied, chromium atoms diffused into the NiAl lattice. The heat treatment of this structure led to the formation of the (NiCr)Al intermetallic compound as well as Al2O3 with crystalline sizes of 23 nm and 58 nm, respectively.

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23

Ksiazek, Marzanna, Lukasz Boron, and Adam Tchorz. "Study on the Microstructure, Mechanical Properties, and Erosive Wear Behavior of HVOF Sprayed Al2O3-15 wt.%TiO2 Coating with NiAl Interlayer on Al-Si Cast Alloy." Materials 13, no. 18 (September 16, 2020): 4122. http://dx.doi.org/10.3390/ma13184122.

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Alumina oxide coatings are widely used in many industrial applications to improve corrosion protection, wear and erosion resistances, and thermal insulation of metallic surfaces. The paper presents study of the microstructure, mechanical, and wear properties of HVOF (high velocity oxy-fuel process) sprayed of Al2O3-15 wt.% TiO2 coating with the NiAl interlayer on the surface of Al-Si alloy castings. The microstructure of Al2O3-15 wt.% TiO2/NiAl coating was characterized by light microscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS). The analysis of the microstructure showed the formation of coating with low porosity, compact structure, good adhesion to the substrate with typical lamellar structure composed of a solid phase consisting of compounds included in the coating material and their phase variations. For analysis of the adhesion of coatings to the substrate, the scratch test was applied. An assessment of the erosive wear resistance of coatings was also carried out, confirming the significant impact of the interlayer as well as the microstructure and phase composition of the oxide coating on the wear resistance of the tested coating system. Moreover, the results were discussed in relation to the bending strength test, including cracks and delamination in the system of the Al2O3-15 wt.% TiO2/NiAl/Al-Si alloy as microhardness and erosion resistance of the coating. It was found that the introduction of the NiAl metallic interlayer significantly increased resistance to cracking and wear behavior in the studied system.

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Novák, R., F. Čermák, and Ľ. Kalivoda. "Study of Al2O3 and NiAlAl2O3 coatings with acoustic emission analysis." Materials Science and Engineering: A 139 (July 1991): 264–67. http://dx.doi.org/10.1016/0921-5093(91)90627-y.

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25

Feldshtein, E., P. Kiełek, T. Kiełek, L. Dyachkova, and A. Letsko. "On Some Mechanical Properties and Wear Behavior of Sintered Bronze Based Composites Reinforced with Some Aluminides Microadditives." International Journal of Applied Mechanics and Engineering 22, no. 2 (May 24, 2017): 293–302. http://dx.doi.org/10.1515/ijame-2017-0017.

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AbstractIn the paper, the changes in some mechanical properties and wear behavior of CuSn10 sintered bronze and MMCs based on this bronze reinforced with composite ultrafine aluminide powders FeAl/15 % Al2O3, NiAl/15 % Al2O3and Ti-46Al-8Cr are described. It was observed that the presence of aluminides in the MMCs leads to an increase in the hardness, but the flexural strength may increase or decrease depending on the type of aluminide. The presence of aluminides in the MMC reduces the wear rate considerably. It is decreased in the direction of FeAl/15 % Al2O3→ NiAl/15 % Al2O3→ Ti-46Al-8Cr aluminides and for the best MMC composition the advantage is about 20 times. In the MMCs wear process, micro-craters are formed on the contact surface and it is the principal reason of a decrease in the wear rate.

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26

Helms, Andrew B., James S. Burgess, and Shane C. Street. "Surface studies of 2,4-pentanedione on γ-Al2O3/NiAl (100) and NiAl (100)." Surface Science 603, no. 22 (November 2009): 3262–66. http://dx.doi.org/10.1016/j.susc.2009.09.008.

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27

Chang, S. T., W. H. Tuan, H. C. You, and I. C. Lin. "Effect of surface grinding on the strength of NiAl and Al2O3/NiAl composites." Materials Chemistry and Physics 59, no. 3 (June 1999): 220–24. http://dx.doi.org/10.1016/s0254-0584(99)00060-7.

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28

Dercz, Grzegorz, Krystian Prusik, Lucjan Pająk, Tomasz Goryczka, and Bolesław Formanek. "X-ray studies on NiAl–Cr3C2–Al2O3 composite powder with nanocrystalline NiAl phase." Journal of Alloys and Compounds 423, no. 1-2 (October 2006): 112–15. http://dx.doi.org/10.1016/j.jallcom.2005.12.044.

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29

Miller, D. P., J. J. Lannutti, and R. D. Noebe. "Fabrication and properties of functionally graded NiAl/Al2O3 composites." Journal of Materials Research 8, no. 8 (August 1993): 2004–13. http://dx.doi.org/10.1557/jmr.1993.2004.

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A modified sedimentation process was used in the production of a functionally gradient material (FGM), NiAl/Al2O3. A simple finite element model was used to guide our design and fabrication efforts by estimating residual stress states as a function of composite structure. This approach could lead to tailored designs that enhance or avoid specific residual stress states. Thermal cycling tests were factored into the model to predict time dependent or steady-state internal temperature and stress profiles. Four-point bend tests were conducted to establish the mechanical load-displacement behavior of a single interlayer FGM at room temperature, 800 and 1000 K. Room temperature bend strength of the FGM was 3–4 times that of the base NiAl. At elevated temperatures, composite fracture occurred in a gradual, noncatastrophic mode involving NiAl retardation of a succession of cracks originating in the alumina face.

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30

Taniguchi, Shigeji. "Discussions on some Properties of Alumina Scales and their Protectiveness." Materials Science Forum 696 (September 2011): 51–56. http://dx.doi.org/10.4028/www.scientific.net/msf.696.51.

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This small review deals mainly with three issues regarding the nature and protectiveness of alumina scales grown during high-temperature oxidation: (1) sequences of phase transportation of alumina scales formed on Fe-Cr-Al and NiAl alloys, and a few aluminides, (2) combined additions of reactive element (RE) and (3) convolution of α-Al2O3 scales. Though the general phase transformation sequence of alumina scales is γ to θ to α phases at intermediate temperatures, variations have been reported. Directional growth of transient aluminas such as γ-Al2O3 and θ-Al2O3 is discussed with a particular emphasis on its driving force. Parabolic rate constants for the growth of α-Al2O3scales are smaller when the period of transient alumina is longer because of larger α-Al2O3grains. The effect of RE in slowing the parabolic oxidation saturates at a certain concentration, however combined addition further decreases the oxidation rate. The α-Al2O3 scales on Fe-Cr-Al alloys without RE are highly convoluted, however those on NiAl and other aluminides are not so convoluted. The α-Al2O3 layer beneath the outer NiO layer or NiAl2O4 layer is flat in the oxidation of Ni3Al. Directions for future work are proposed.

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Vlad, A., A. Stierle, N. Kasper, H. Dosch, and M. Rühle. "Erratum." Journal of Materials Research 22, no. 3 (March 2007): 815. http://dx.doi.org/10.1557/jmr.2006.0397e.

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32

Riyanto, Edy, and Budi Prawara. "Mikrostruktur dan Karakterisasi Sifat Mekanik Lapisan Cr3C2-NiAl-Al2O3 Hasil Deposisi Dengan Menggunakan High Velocity Oxygen Fuel Thermal Spray Coating." Journal of Mechatronics, Electrical Power, and Vehicular Technology 1, no. 1 (March 9, 2012): 1–4. http://dx.doi.org/10.14203/j.mev.2010.v1.1-4.

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Surface coating processing of industrial component with thermal spray coatings have been applied in many industrial fields. Ceramic matrix composite coating which consists of Cr3C2-Al2O3-NiAl had been carried out to obtain layers of material that has superior mechanical properties to enhance component performance. Deposition of CMC with High Velocity Oxygen Fuel (HVOF) thermal spray coating has been employed. This study aims to determine the effect of powder particle size on the microstructure, surface roughness and hardness of the layer, by varying the NiAl powder particle size. Test results show NiAl powder particle size has an influence on the mechanical properties of CMC coating. Hardness of coating increases and surface roughness values of coating decrease with smaller NiAl particle size.

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33

Lou, Jin, and Cheng Xiang Ruan. "Cyclic Oxidation Resistance of Hot-Dipping Aluminized GH169." Advanced Materials Research 1061-1062 (December 2014): 436–40. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.436.

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GH169 superalloy steel was coated by hot-dipping in a molten aluminum bath, and then diffusing annealing at 950 °C for 2h. The cyclic oxidation behaviors of the hot-dipped aluminized steel and GH169 were tested at 900 °C for 24 cycles using resistance furnace. Morphology of surface and cross-section, element distribution of the oxide scale were characterized by SEM and EDS. The results showed that protective Cr2O3 and Al2O3 oxide scales were formed on GH169 and aluminized steel after 24 cycles, respectively. The inner oxidation was found on GH169 after 24 cycles. It was composed of surface Al2O3 oxide film, outer Al-rich layer scattered with NiAl phase, and inner NiAl layer on aluminized steel after 24 cycles at 900°C.

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34

Abe, Osami, and Akira Tsuge. "Synthesis of intermetallic NiAl and Ni3Al fine powders through organometallic precursors." Journal of Materials Research 6, no. 5 (May 1991): 928–34. http://dx.doi.org/10.1557/jmr.1991.0928.

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Fine powders of intermetallic NiAl and Ni3Al were synthesized through organometallic precursors, which were coprecipitated from aqueous solutions of NiCl2 and AlCl3 by the addition of ammonium benzoate and hydradinium monochloride as precipitants. Ni3Al and NiAl were synthesized by a two-step heat treatment of the precursors. The initial step was the thermal decomposition of organic groups to form homogeneous mixtures of Ni3C, amorphous Al2O3, and free C below 1000 °C. The other step was the reaction above 1300 °C to form the intermetallics. Single phase powders of NiAl and Ni3Al with the particle size less than 3 μm were obtained above 1300 and 1400 °C, respectively.

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35

Sheng, Li Yuan. "Microstructure, Mechanical and Tribological Properties of the Rapidly Solidified NiAl/Cr(Mo,Dy) Hypoeutectic Alloy." Materials Science Forum 849 (March 2016): 590–96. http://dx.doi.org/10.4028/www.scientific.net/msf.849.590.

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The NiAl/Cr (Mo,Dy) hypoeutectic alloy was fabricated by rapid solidification. The microstructure and mechanical properties as well as tribological properties for the alloy at different temperatures were investigated. The results revealed that the rapidly solidified NiAl/Cr (Mo,Dy) hypoeutectic alloy was composed of primary NiAl, fine NiAl/Cr (Mo) eutectic lamella, Ni5Dy phase and Cr7Ni3 precipitate. The compression test showed that the rapid solidification improved the mechanical properties of the NiAl/Cr (Mo,Dy) hypoeutectic alloy obviously. The dry sliding test results showed that alloy had excellent tribological properties at about 1073 K, which obtained wear rate of 4.9 10-14m3/m·N and friction coefficient of 0.16 μ. The excellent tribological properties at high temperature may be attributed to the continuous and intact protecting lubricant film which was composed of amorphous, Cr2O3 and Al2O3 nanoparticles. Between 700 K to 900 K, the alloy demonstrated bad tribological properties, especially the high wear rate, which may be ascribed to the softening of NiAl and Cr (Mo) phases.

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36

Moshksar, M. M., H. Doty, and R. Abbaschian. "Grain growth in NiAlAl2O3 in situ composites." Intermetallics 5, no. 5 (January 1997): 393–99. http://dx.doi.org/10.1016/s0966-9795(97)00006-x.

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37

Yang, J. C., K. Nadarzinski, E. Schumann, and M. Rühle. "Electron microscopy studies of NiAl/γ-Al2O3 interfaces." Scripta Metallurgica et Materialia 33, no. 7 (October 1995): 1043–48. http://dx.doi.org/10.1016/0956-716x(95)00341-r.

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38

Wang, L., K. Xu, R. R. Bowman, and R. J. Arsenault. "Interfaces in continuous filament-reinforced Al2O3/NiAl composites." Metallurgical and Materials Transactions A 26, no. 4 (April 1995): 897–903. http://dx.doi.org/10.1007/bf02649086.

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39

Troncy, R., G. Bonnet, and F. Pedraza. "Synthesis of self-regenerating NiAl-Al2O3 composite coatings." Materials Chemistry and Physics 279 (March 2022): 125647. http://dx.doi.org/10.1016/j.matchemphys.2021.125647.

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40

Lee, Hyunju, and Doohwan Lee. "Synthesis Chemistry and Properties of Ni Catalysts Fabricated on SiC@Al2O3 Core-Shell Microstructure for Methane Steam Reforming." Catalysts 10, no. 4 (April 2, 2020): 391. http://dx.doi.org/10.3390/catal10040391.

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Heat and mass transport properties of heterogeneous catalysts have significant effects on their overall performance in many industrial chemical reaction processes. In this work, a new catalyst micro-architecture consisting of a highly thermally conductive SiC core with a high-surface-area metal-oxide shell is prepared through a charge-interaction-induced heterogeneous hydrothermal construction of SiC@NiAl-LDH core-shell microstructures. Calcination and reduction of the SiC@NiAl-LDH core-shell results in the formation of Ni nanoparticles (NPs) dispersed on SiC@Al2O3, referred to as Ni/SiC@Al2O3 core-shell catalyst. The Ni/SiC@Al2O3 exhibit petal-like shell morphology consisting of a number of Al2O3 platelets with their planes oriented perpendicular to the surface, which is beneficial for improved mass transfer. For an extended period of methane-stream-reforming reaction, the Ni/SiC@Al2O3 core-shell structure remained stable without any significant degradation at the core/shell interface. However, the catalyst suffered from coking and sintering likely associated with the relatively large Ni particle sizes and the low Al2O3 content. The synthesis procedure and chemistry for construction of supported Ni catalyst on the core-shell microstructure of the highly thermal conductive SiC core, and the morphology-controlled metal-oxide shell, could provide new opportunities for various catalytic reaction processes that require high heat flux and enhanced mass transport.

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41

Miura, Seiji, Yoshihito Sekito, Takuya Okawa, Takuya Yamanouchi, and Tetsuo Mohri. "Phase Equilibrium between B2 Aluminide NiAl and Nb-Mo bcc Solid Solution Phase." Materials Science Forum 783-786 (May 2014): 1171–75. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1171.

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In order to understand the composition of the Nb-Mo bcc phase suitable to introduce B2-NiAl phase for the improvement of oxidation resistance as an Al reservoir layer for maintaining Al2O3 surface layer, a NiAl-Nb-Mo section of the quaternary Al-Nb-Ni-Mo phase diagram is studied. It is found that the ternary τ2 phase appears in wide composition range of alloys, both the hardness and cracking tendency decreases with increasing the Mo concentration of the alloys.

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42

Schumann, E., J. C. Yang, K. Nadarzinski, and M. Ruhle. "EM studies of oxidized Y and Zr-doped β-NiAl." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 672–73. http://dx.doi.org/10.1017/s0424820100171092.

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The highly beneficial effect of yttrium and zirconia dopants on the oxidation behaviour of β-NiAl has been known for over the past 50 years. Various theories have been proposed to explain the reactive element effect. The dopants may: improve the interfacial properties; favorably effect diffusion in the oxide scale; or getter the sulfur, which is a common impurity in nickel alloys, and prevents sulfur from diffusing to the interface where it may decrease the interfacial energy.To help determine which theory(s) explain the reactive element effect, we have examined oxidized Zr and Y doped β-NiAl by cross-section electron microscopy techniques on a VG-HB501 STEM and JEOLARM1250 in order to characterize the microstructure and the locations of the dopants.Polycrystalline 0.1% Y doped β-NiAl were oxidized at 1200°C for 24 hr and polycrystalline 0.1% Zr doped β-NiAl were oxidized at 1200°C for 200 hr. The CTEM images of the Zr (Fig. 1) and the Y (Fig. 2) doped NiAl show that α-Al2O3 scale forms after oxidation.

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43

Puszynski, Jan A. "Recent Advances in Synthesis and Densification of Nanomaterials in Self-Propagating High-Temperature Regime." Advances in Science and Technology 45 (October 2006): 994–1004. http://dx.doi.org/10.4028/www.scientific.net/ast.45.994.

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This invited talk reviews recent advances in synthesis of nanopowders in selfpropagating high-temperature regime with emphasis on chemically-assisted combustion synthesis of nonoxide ceramic nanopowders, specifically SiC, Si3N4, and AlN-BN. Recent results of in-situ densification of intermetallic-ceramic composites formed from nanosized reactants in a combustion regime are also presented. Examples of combustion synthesized TiAl3-Al2O3 and NiAl-Al2O3-CNT nanocomposites are included and discussed.

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44

Shibata, Yoshimitsu, Shigenari Hayashi, and Toshio Narita. "Effect of Zirconium on Cyclic-Oxidation of Ni-40Cr-3Re Alloys with α-Cr / β-NiAl Coatings." Materials Science Forum 522-523 (August 2006): 369–76. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.369.

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A coating with duplex structure of a outer β-NiAl and an inner α-Cr layer, was formed on a Ni-40Cr-3Re (in at%) alloy with or without Zr addition, and the coated alloys were oxidized under thermal cycling in air for up to 2300ks. The coated alloys containing Zr showed a two-step parabolic oxidation, the kp1st in the early stage of oxidation was 2.6~5.4×10-11 kg2 m-4 s-1 for four alloys tested, and kp 2nd for the longer oxidation increased with increasing Zr content from 2.6~5.4×10-11 for the alloy with 0.1at%Zr to 9.6×10-11 kg2 m-4 s-1 for the alloy with 1.0at%Zr. The rapid oxidation for the alloy with 1.0at%Zr is due to the formation of ZrO2 as an internal oxide. The oxide scale in the 1st stage consisted of both α- and θ- Al2O3 with whiskers, and with further oxidation the α-Al2O3 became the major product in the 2nd stage. After the oxidation for 2300ks the as-prepared, outer β-NiAl was changed into a mixture of β-NiAl and γ’-Ni3Al for the Ni-40Cr-3Re alloy containing Zr, while in the coated Ni-40Cr-3Re alloy the outer layer became a mixture of γ’-Ni3Al and γ-Ni(Al,Cr). It was concluded that the addition of Zr into the coated Ni-40Cr-3Re alloy helps maintain high Al contents in the outer Ni-aluminide layer by forming a protective Al2O3 layer.

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45

Handke, Bartosz, Jens Bæk Simonsen, Martin Bech, Zheshen Li, and Preben Juul Møller. "Iron oxide thin film growth on Al2O3/NiAl(110)." Surface Science 600, no. 24 (December 2006): 5123–30. http://dx.doi.org/10.1016/j.susc.2006.08.047.

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46

Nepijko, S. A., M. Klimenkov, H. Kuhlenbeck, D. Zemlyanov, D. Herein, R. Schlögl, and H. J. Freund. "TEM study of tantalum clusters on Al2O3/NiAl(110)." Surface Science 412-413 (September 1998): 192–201. http://dx.doi.org/10.1016/s0039-6028(98)00387-2.

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47

Worren, T., K. Højrup Hansen, E. Lægsgaard, F. Besenbacher, and I. Stensgaard. "Copper clusters on Al2O3/NiAl(110) studied with STM." Surface Science 477, no. 1 (April 2001): 8–16. http://dx.doi.org/10.1016/s0039-6028(01)00703-8.

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48

Luo, M. F., C. I. Chiang, H. W. Shiu, S. D. Sartale, and C. C. Kuo. "Patterning Co nanoclusters on thin-film Al2O3/NiAl(100)." Nanotechnology 17, no. 2 (December 14, 2005): 360–66. http://dx.doi.org/10.1088/0957-4484/17/2/003.

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49

Drachsel, W., M. Adelt, N. Nilius, and H. J. Freund. "Cathodoluminescence of small silver particles on Al2O3/NiAl (110)." Journal of Electron Spectroscopy and Related Phenomena 122, no. 3 (March 2002): 239–49. http://dx.doi.org/10.1016/s0368-2048(01)00361-9.

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50

Lykhach, Y., V. Moroz, and M. Yoshitake. "Formation of epitaxial Al2O3/NiAl(110) films: aluminium deposition." Applied Surface Science 241, no. 1-2 (February 2005): 250–55. http://dx.doi.org/10.1016/j.apsusc.2004.09.041.

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