The possibility to use TiAl intermetallics for high temperature applications

International Nuclear Information System (INIS)

Molotkov, A.V.

1993-01-01

Titanium aluminide TiAl is the promising heat resisting structural material with operation temperature up to 850-900 deg C. This intermetallic compound is characterized by low density and high specific values of elasticity moduli and heat resistance properties in wide temperature range, as compared to known heat resisting titanium, iron and nickel base alloys. Test batch of pressed blades was manufactured of TiAl with the use of powder technology. Results of testing showed, that endurance strength of blades exceeded by 30% the strength, required for operation. The calculations showed, that the use of such blades in gas-turbine cagines could provide 30-40% decrease of mass of compressor blading

Investigation of passivity and its breakdown on Fe3Al–Si and Fe3Al–Ge intermetallics in chloride-containing solution

International Nuclear Information System (INIS)

Rosalbino, F.; Carlini, R.; Parodi, R.; Zanicchi, G.; Scavino, G.

2014-01-01

Highlights: • Passivity and its breakdown on Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides was investigated. • Investigation was performed in borate buffer solution with and without 100 mM KCl. • Polarization, potentiostatic transients and impedance measurements have been employed. • Results have been compared with those obtained on Fe 3 Al intermetallic. • Si and Ge improve the resistance to localized corrosion of Fe 3 Al. - Abstract: The passivity and passivity breakdown of Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides were studied in borate buffer solution (pH 8.4) in the absence and presence of 100 mM KCl, performing potentiodynamic polarization, potentiostatic transients and electrochemical impedance spectroscopy (EIS) measurements complemented with scanning electron microscopy (SEM). In the absence of chloride ions Si and Ge exercise a beneficial role in the passivating characteristics of Fe 3 Al intermetallic. Addition of Si or Ge significantly modifies the electrochemical response of iron aluminide Fe 3 Al resulting in a more stable passive film. In the presence of chloride ions all the intermetallic compounds experience localized corrosion (pitting). However, Si and Ge alloying additions increase the breakdown potential and the extent of passivation domain, indicating improved resistance to initiation of pitting corrosion. Furthermore, EIS measurements performed at the breakdown state evidenced higher R ct and lower depression angle values for Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides compared to Fe 3 Al intermetallic, confirming their better localized corrosion behavior. The improved resistance to pitting corrosion results from the enhanced protective function of passive film due to the presence of Si or Ge that inhibit pit initiation by hindering the adsorption of Cl − ions at the metal surface

Microstructure of two phases alloy Al{sub 3}Ti/Al{sub 3}Ti{sub 0.75}Fe{sub 0.25}; Microestructura de una aleacion de dos fases Al{sub 3}Ti/Al{sub 3}Ti{sub 0.75}Fe{sub 0.25}

Energy Technology Data Exchange (ETDEWEB)

Angeles, C; Rosas, G; Perez, R [Instituto Nacional de Investigaciones Nucleares, Departamento de Sintesis y Caracterizacion de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

The titanium-aluminium system presents three intermetallic compounds from those Al{sub 3}Ti is what less attention has received. The objective of this work is to generate and characterize the microstructure of multiphase alloys nearby to Al{sub 3}Ti compound through Fe addition as alloying. This is because it has been seen that little precipitates of Al{sub 2}Ti phase over Al{sub 3}Ti intermetallic compound increases its ductility. (Author)

The chemical phenol extraction of intermetallic particles from casting AlSi5Cu1Mg alloy.

Science.gov (United States)

Mrówka-Nowotnik, G; Sieniawski, J; Nowotnik, A

2010-03-01

This paper presents a chemical extraction technique for determination of intermetallic phases formed in the casting AlSi5Cu1Mg aluminium alloy. Commercial aluminium alloys contain a wide range of intermetallic particles that are formed during casting, homogenization and thermomechanical processing. During solidification, particles of intermetallics are dispersed in interdendritic spaces as fine primary phases. Coarse intermetallic compounds that are formed in this aluminium alloy are characterized by unique atomic arrangement (crystallographic structure), morphology, stability, physical and mechanical properties. The volume fraction, chemistry and morphology of the intermetallics significantly affect properties and material behaviour during thermomechanical processing. Therefore, accurate determination of intermetallics is essential to understand and control microstructural evolution in Al alloys. Thus, in this paper it is shown that chemical phenol extraction method can be applied for precise qualitative evaluation. The results of optical light microscopy LOM, scanning electron microscopy SEM and X-ray diffraction XRD analysis reveal that as-cast AlSi5Cu1Mg alloy contains a wide range of intermetallic phases such as Al(4)Fe, gamma- Al(3)FeSi, alpha-Al(8)Fe(2)Si, beta-Al(5)FeSi, Al(12)FeMnSi.

Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

International Nuclear Information System (INIS)

Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

2005-01-01

In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

Interface electron structure of Fe3Al/TiC composites

Institute of Scientific and Technical Information of China (English)

PANG Lai-xue; SUN Kang-ning; SUN Jia-tao; FAN Run-hua; REN Shuai

2006-01-01

Based on YU's solids and molecules emperical electron theory(EET), interface valence electron structure of TiC-Fe3Al composites was set up, and the valence electron density of different atomic states TiC and Fe3Al composites in various planes was determined. The results indicate that the electron density of (100)Fe3Al is consistent with that of (110)TiC in the first-class approximation, the absolute value of minimum electron density difference along the interface is 0.007 37 nm-2, and the relative value is 0.759%. (110)TiC//(100)Fe3Al preferred orientation is believed to benefit the formation of the cuboidal shape TiC. In the other hand, it shows that the particle growth is accompanied by the transport of electron, the deviation continuity of electron density intrinsically hinders the grain growth. The electron density of (100)TiC is not consistent with Fe3Al arbitrary crystallographic plane,thus it well explains that the increased titanium and carbon contents do not increase the size of large particles. The crystallographic orientation of (110)TiC//(100)FeAl will improve the mechanical properties. Therefore interface electron theory is an effective theoretical implement for designing excellent property of composites.

Elimination of Iron Based Particles in Al-Si Alloy

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2015-03-01

Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by chrome. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. By experimental work were used three different amounts of AlCr20 master alloy a three different temperature of chill mold. Our experimental work confirmed that chrome can be used as an iron corrector in Al-Si alloy, due to the change of intermetallic phases and shortening their length.

Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

International Nuclear Information System (INIS)

Ohmi, Tatsuya; Matsuura, Kiyotaka; Iguchi, Manabu; Mizuma, Kiminori

2008-01-01

A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen

Chemical vapor deposition of aluminide coatings on iron, nickel and superalloys

International Nuclear Information System (INIS)

John, John T.; De, P.K.; Dubey, Vivekanand; Srinivasa, Raman

2009-08-01

Aluminide coatings are a class of intermetallic coatings applied on nickel and cobalt base superalloys and steels to protect them from different forms of environmental degradation at high temperatures. In this report a CVD system that can produce the aluminide coatings on iron, nickel and nickel base alloys has been described and the result of chemical vapor deposition of aluminide coatings on iron specimens, their characterization, and property evaluation have been presented. The CVD system consists of an AlCl 3 bath, a stainless steel retort as a hot-wall reacto, cold traps and vacuum system. Aluminium chloride vapor was carried in a stream of hydrogen gas at a flow rate of 150 SCCM (standard cubic centimeter per minute) into the CVD reactor maintained in the temperature range of 1173 - 1373 K and at a pressure of 1.33 kPa (10 Torr). Aluminum deposition takes place from aluminium subchlorides produced by reaction between AlCl 3 and pure aluminum kept in the CVD reactor. The aluminum diffuses into the iron samples and iron aluminide phases are formed at the surface. The coatings were shining bright and showed good adherence to the substrate. The coatings consisted of FeAl phase over a wide range of experimental conditions. The growth kinetics of the coating followed a parabolic rate law and the mean activation energy was 212 ±16 kJ/mol. Optical microscopic studies on the transverse section of the coating showed that the aluminide coating on iron consisted of two layers. The top layer had a thickness in the range of 20-50 μm, and the under layer had thickness ranging from 35 to 250 μm depending on coating temperature in two hours. The thickness of the aluminide layer increased with coating duration and temperature. Electron microprobe studies (EPMA) showed that the aluminum concentration decreased steadily as distance from the surface increased. TEM studies showed that the outer most layer had a B2 order (of the FeAl phase), which extended even into the under

Structural evolution of Fe-50 at.% Al powders during mechanical alloying and subsequent annealing processes

International Nuclear Information System (INIS)

Haghighi, Sh. Ehtemam; Janghorban, K.; Izadi, S.

2010-01-01

Iron aluminides, despite having desirable properties like excellent corrosion resistance, present low room-temperature ductility and low strength at high temperatures. Mechanical alloying as a capable process to synthesize nanocrystalline materials is under consideration to modify these drawbacks. In this study, the microstructure of iron aluminide powders synthesized by mechanical alloying and subsequent annealing was investigated. Elemental Fe and Al powders with the same atomic percent were milled in a planetary ball mill for 15 min to 100 h. The powder milled for 80 h was annealed at temperatures of 300, 500 and 700 o C for 1 h. The alloyed powders were disordered Fe(Al) solid solutions which were transformed to FeAl intermetallic after annealing. The effect of the milling time and annealing treatment on structural parameters, such as crystallite size, lattice parameter and lattice strain was evaluated by X-ray diffraction. Typically, these values were 15 nm, 2.92 A and 3.1% for the disordered Fe(Al) solid solution milled for 80 h and were 38.5 nm, 2.896 A and 1.2% for the FeAl intermetallic annealed at 700 o C, respectively.

Precipitation-strengthening effects in iron-aluminides

Energy Technology Data Exchange (ETDEWEB)

Maziasz, P.J.; McKamey, C.G.; Goodwin, G.M. [Oak Ridge National Laboratory, TN (United States)] [and others

1995-05-01

The purpose of this work is to produce precipitation to improve both high-temperature strength and room-temperature ductibility in FeAl-type(B2 phase) iron-aluminides. Previous work has focused on primarily wrought products, but stable precipitates can also refine the grain size and affect the properties of as-cast and/or welded material as well. New work began in FY 1994 on the properties of these weldable, strong FeAl alloys in the as-cast condition. Because the end product of this project is components for industry testing, simpler and better (cheaper, near-net-shape) processing methods must be developed for industrial applications of FeAl alloys.

Remelting of aluminium with the addition of AlTi5B1 and AlTi3C0,15 grain refiners

Directory of Open Access Journals (Sweden)

Dobešrek, M.

2008-04-01

Full Text Available It was found that concentration of boron in aluminium with the addition of AlTi5B1 grain refiner is decreasing during remelting as a consequence of TiB2 particles settling down due to gravity. TiB2 particles remained in aluminium after four remelts shows lower effect of grain refinement compared to non-remelted samples with the same TiB2 content. It was also found that TiC particles are still present in aluminium with the addition of AlTi3C0,15 grain refiner after four remelts and they probably participate in nucleation of α-Al grains.

The effect of graphite precipitates in Ni3Al/C composite on tribological properties

Directory of Open Access Journals (Sweden)

A. Janas

2010-01-01

Full Text Available The study shows the results of investigations of the tribological properties of cast Ni3Al/C composite and compares them with the properties of pure intermetallic phases of the Ni3Al type. An inspiration to these studies was a surprising similarity observed between the microstructure of iron-carbon alloys, and specifically of different cast iron grades, and the microstructure of, absolutely different in terms of the chemical composition, nickel-aluminium alloy. Because of carbon present in the alloy, an attempt was made to determine what effect the presence of graphite (acting as a lubricant might have on the abrasive wear behaviour of alloy during lubricated friction test. Tests were made on a Miller apparatus, used for active testing of the abrasive wear resistance. The specimen loss of mass was determined in function of time.

Microstructure and high temperature oxidation resistance of in-situ synthesized TiN/Ti_3Al intermetallic composite coatings on Ti6Al4V alloy by laser cladding process

International Nuclear Information System (INIS)

Liu, Hongxi; Zhang, Xiaowei; Jiang, Yehua; Zhou, Rong

2016-01-01

High temperature anti-oxidation TiN/Ti_3Al intermetallic composite coatings were fabricated with the powder and AlN powder on Ti6Al4V titanium alloy surface by 6 kW transverse-flow CO_2 laser apparatus. The chemical composition, morphology and microstructure of the TiN/Ti_3Al composite coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high temperature oxidation resistance of TiN/Ti_3Al coating, the isothermal oxidation test was performed in a high temperature resistance furnace at 600 °C and 800 °C, respectively. The result shows that the composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like or dendrites), with an even distribution in Ti_3Al matrix. It indicates that a physical and chemical reaction between Ti powder and AlN powder has completely occurred under the laser irradiation condition. In addition, the microhardness of the TiN/Ti3Al intermetallic composite coating is 3.4 times higher than that of the Ti6Al4V alloy substrate and reaches 844 HV_0_._2. The high temperature oxidation behavior test reveals that the high temperature oxidation resistance of TiN/Ti_3Al composite coating is much better than that of titanium alloy substrate. The excellent high temperature oxidation resistance of TiN/Ti_3Al intermetallic composite coating is attributed to the formation of reinforced phases TiN, Al_2O_3 and TiO_2. The laser cladding TiN/Ti_3Al intermetallic composite coating is anticipated to be a promising high temperature oxidation resistance coating for Ti6Al4V alloy. - Highlights: • In-situ TiN/Ti_3Al composite coating was synthesized on Ti6Al4V alloy by laser cladding. • The influence of Ti and AlN molar ratio on the microstructure of the coating was studied. • The TiN/Ti_3Al intermetallic coating is mainly composed of α-Ti, TiN and Ti_3Al phases. • The

Effect of Iron and Magnesium on Alloy AL9M Structure and Properties

Science.gov (United States)

Bazhenov, V. E.; Koltygin, A. V.; Belov, V. D.

2017-09-01

The effect of iron impurity on the structure and properties of aluminum alloy AL9M, especially its action on magnesium distribution within the structure, is studied. The microstructure of a cast component of this alloy broken during operation is analyzed. It is shown that iron impurity has an unfavorable effect on structure and mechanical properties of a casting due to appearance of Al9Fe2Si and Al18Fe2Mg7Si10 intermetallics. Formation of these intermetallics consumes a considerable amount of magnesium and lowers the content of the Q(Al5Cu2Mg8Si6) strengthening phase in the alloy structure.

Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

Science.gov (United States)

Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

2010-11-01

A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

Fabrication of FeAl Intermetallic Foams by Tartaric Acid-Assisted Self-Propagating High-Temperature Synthesis

Directory of Open Access Journals (Sweden)

Krzysztof Karczewski

2018-04-01

Full Text Available Iron aluminides are intermetallics with interesting applications in porous form thanks to their mechanical and corrosion resistance properties. However, making porous forms of these materials is not easy due to their high melting points. We formed FeAl foams by elemental iron and aluminum powders sintering with tartaric acid additive. Tartaric acid worked as an in situ gas-releasing agent during the self-propagating high-temperature synthesis of FeAl intermetallic alloy, which was confirmed by X-ray diffraction measurements. The porosity of the formed foams was up to 36 ± 4%. In the core of the sample, the average equivalent circle diameter was found to be 47 ± 20 µm, while on the surface, it was 35 ± 16 µm; thus, the spread of the pore size was smaller than reported previously. To investigate functional applications of the formed FeAl foam, the pressure drop of air during penetration of the foam was examined. It was found that increased porosity of the material increased the flow of the air through the metallic foam.

The shock Hugoniot of the intermetallic alloy Ti-46.5Al-2Nb-2Cr

International Nuclear Information System (INIS)

Millett, Jeremy; Gray, George T. Rusty III; Bourne, Neil

2000-01-01

Plate impact experiments were conducted on a γ-titanium aluminide (TiAl) based ordered intermetallic alloy. Stress measurements were recorded using manganin stress gauges supported on the back of TiAl targets using polymethylmethacrylate windows. The Hugoniot in stress-particle velocity space for this TiAl alloy was deduced using impedance matching techniques. The results in this study are compared to the known Hugoniot data of the common alpha-beta engineering Ti-based alloy Ti-6Al-4V. The results of the current study on the intermetallic alloy TiAl support that TiAl possesses a significantly higher stress for a given particle velocity than the two-phase Ti-6Al-4V alloy. (c) 2000 American Institute of Physics

Synthesis of Fe-Al-Ti Based Intermetallics with the Use of Laser Engineered Net Shaping (LENS

Directory of Open Access Journals (Sweden)

Monika Kwiatkowska

2015-04-01

Full Text Available The Laser Engineered Net Shaping (LENS technique was combined with direct synthesis to fabricate L21-ordered Fe-Al-Ti based intermetallic alloys. It was found that ternary Fe-Al-Ti alloys can be synthesized using the LENS technique from a feedstock composed of a pre-alloyed Fe-Al powder and elemental Ti powder. The obtained average compositions of the ternary alloys after the laser deposition and subsequent annealing were quite close to the nominal compositions, but the distributions of the elements in the annealed samples recorded over a large area were inhomogeneous. No traces of pure Ti were observed in the deposited alloys. Macroscopic cracking and porosity were observed in all investigated alloys. The amount of porosity in the samples was less than 1.2 vol. %. It seems that the porosity originates from the porous pre-alloyed Fe-Al powders. Single-phase (L21, two-phase (L21-C14 and multiphase (L21-A2-C14 Fe-Al-Ti intermetallic alloys were obtained from the direct laser synthesis and annealing process. The most prominent feature of the ternary Fe-Al-Ti intermetallics synthesized by the LENS method is their fine-grained structure. The grain size is in the range of 3–5 μm, indicating grain refinement effect through the highly rapid cooling of the LENS process. The Fe-Al-Ti alloys synthesized by LENS and annealed at 1000 °C in the single-phase B2 region were prone to an essential grain growth. In contrast, the alloys annealed at 1000 °C in the two-phase L21-C14 region exhibited almost constant grain size values after the high-temperature annealing.

Method of preparing an Al-Ti-B grain refiner for aluminium-comprising products, and a method of casting aluminium products

NARCIS (Netherlands)

Brinkman, H.J.; Duszczyk, J.; Katgerman, L.

1999-01-01

The invention relates to a method of preparing an Al-Ti-B grain refiner for cast aluminium-comprising products. According to the invention the preparation is realized by mixing powders selected from the group comprising aluminium, titanium, boron, and alloys and intermetallic compounds thereof,

Phase Constituents and Microstructure of Ti3Al/Fe3Al + TiN/TiB2 Composite Coating on Titanium Alloy

Science.gov (United States)

Li, Jianing; Chen, Chuanzhong; Zhang, Cuifang

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be used to improve the Fe3Al + B4C/TiN laser-cladded coating on the Ti-6Al-4V alloy. Furthermore, during the cladding process, C consumed the oxygen in Fe3Al + B4C /TiN + Al2O3 molten pool, which retarded the productions of the redundant metal oxides.

Microstructure and high temperature oxidation resistance of in-situ synthesized TiN/Ti{sub 3}Al intermetallic composite coatings on Ti6Al4V alloy by laser cladding process

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongxi, E-mail: piiiliuhx@sina.com; Zhang, Xiaowei; Jiang, Yehua; Zhou, Rong

2016-06-15

High temperature anti-oxidation TiN/Ti{sub 3}Al intermetallic composite coatings were fabricated with the powder and AlN powder on Ti6Al4V titanium alloy surface by 6 kW transverse-flow CO{sub 2} laser apparatus. The chemical composition, morphology and microstructure of the TiN/Ti{sub 3}Al composite coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high temperature oxidation resistance of TiN/Ti{sub 3}Al coating, the isothermal oxidation test was performed in a high temperature resistance furnace at 600 °C and 800 °C, respectively. The result shows that the composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like or dendrites), with an even distribution in Ti{sub 3}Al matrix. It indicates that a physical and chemical reaction between Ti powder and AlN powder has completely occurred under the laser irradiation condition. In addition, the microhardness of the TiN/Ti3Al intermetallic composite coating is 3.4 times higher than that of the Ti6Al4V alloy substrate and reaches 844 HV{sub 0.2}. The high temperature oxidation behavior test reveals that the high temperature oxidation resistance of TiN/Ti{sub 3}Al composite coating is much better than that of titanium alloy substrate. The excellent high temperature oxidation resistance of TiN/Ti{sub 3}Al intermetallic composite coating is attributed to the formation of reinforced phases TiN, Al{sub 2}O{sub 3} and TiO{sub 2}. The laser cladding TiN/Ti{sub 3}Al intermetallic composite coating is anticipated to be a promising high temperature oxidation resistance coating for Ti6Al4V alloy. - Highlights: • In-situ TiN/Ti{sub 3}Al composite coating was synthesized on Ti6Al4V alloy by laser cladding. • The influence of Ti and AlN molar ratio on the microstructure of the coating was studied. • The TiN/Ti{sub 3}Al intermetallic

Effect of Iron-Containing Intermetallic Particles on the Corrosion Behaviour of Aluminium

DEFF Research Database (Denmark)

Ambat, Rajan

2006-01-01

The effect of heat treatment on the corrosion behaviour of binary Al-Fe alloys containing iron at levels between 0.04 and 0.42 wt.% was investigated by electrochemical measurements in both acidic and alkaline chloride solutions. Comparing solution heat-treated and quenched materials with samples...... with {100} facets, and are observed to contain numerous intermetallic particles. Fine facetted filaments also radiate out from the periphery of pits. The results demonstrate that the corrosion of "pure" 99.96% Al is thus dominated by the role of iron, which is the main impurity, and its electrochemical...... that had been subsequently annealed to promote precipitation of Al3Fe intermetallic particles, it was found that annealing increases both the cathodic and anodic reactivity. The increased cathodic reactivity is believed to be directly related to the increased available surface area of the iron...

Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Buchanan, R.A.; Perrin, R.L.

1996-09-01

Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, and a disordered low-aluminum Fe-Al alloy, FAPY. Tests were performed in a mild acid-chloride solution to simulate aggressive atmospheric corrosion. Cyclic-anodic-polarization tests were employed to evaluate resistances to localized aqueous corrosion. The high-temperature oxide surfaces consistently produced detrimental results relative to mechanically or chemically cleaned surfaces. Specifically, the pitting corrosion resistances were much lower for the as-processed and 750{degrees} C surfaces, relative to the cleaned surfaces, for FA-84, FA-129, FAL-Mo, FA-385 and FAPY. Furthermore, the pitting corrosion resistances were much lower for the 1000{degrees}C surfaces, relative to cleaned surfaces, for FA-129, FAL and FAL-Mo.

Refinement of the Fe4Al13 structure and its relationship to the quasihomological homeotypical structures

International Nuclear Information System (INIS)

Grin, J.; Burkhardt, U.; Ellner, M.; Peters, K.

1994-01-01

The crystal structure of Fe 4 Al 13 was refined using single crystal diffractometer data: pearson symbol mC102, space group C2/m; a=15.492(2) A, b=8.078(2) A, c=12.471(1) A, β=107.69(1) ; R F =0.053, R F (w)=0.044 for 1127 reflections and 137 refined parameters. The coordination numbers of atoms are 9, 10, 11 for iron and 10, 12, 13, 14 for aluminium. The shortest interatomic distances are: Fe-Fe - 2.902 A, Fe-Al - 2.374 A, Al-Al - 2.533 A. A preferred occupation of pentagonal prismatic coordinated positions by aluminium was found. The structural relationship between the Fe 4 Al 13 structure and chemically homologous and homeotypical structures of aluminium and gallium containing systems with the 3d transition metals is discussed. The greatest similarity was found concerning the coordination polyhedra, especially that of transition metal atoms. The main common feature of these homeotypical structures is the presence of pentagonal ''channels'', which is strongly dependent on the chemical composition. With increasing atomic number of the 3d transition metal, the stability range of these structures shifts to the transition metal-rich concentration. It is concluded that there is a connection between the occurrence of aluminium and gallium-containing decagonal and icosahedral phases and the existence of the infinite one-dimensional pentagonal channels in the intermetallic compounds showing a similar chemical composition. (orig.)

Creep of cast Fe-36Al-2Ti alloy

Czech Academy of Sciences Publication Activity Database

Dobeš, Ferdinand; Kratochvíl, P.; Milička, Karel

2006-01-01

Roč. 14, 10-11 (2006), s. 1199-1203 ISSN 0966-9795. [EUROMAT 2005. Praha, 05.09.2005-08.09.2005] R&D Projects: GA ČR(CZ) GA106/05/0409 Institutional research plan: CEZ:AV0Z20410507 Keywords : iron aluminides, based on FeAl * creep * mechanical testing Subject RIV: JG - Metallurgy Impact factor: 1.943, year: 2006

Fabrication and thermal characterization of amorphous and nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti compound

Energy Technology Data Exchange (ETDEWEB)

Tavoosi, Majid, E-mail: ma.tavoosi@gmail.com

2017-01-15

In this study, the fabrication and structural characterization of amorphous/nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti phase has been performed. In this regards, milling and annealing processes were applied on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} (at. %) powder mixture for different periods of time. The prepared samples were characterized using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and differential scanning calorimetery (DSC). According to the results, supersaturated solid solution, nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti (with average crystallite size of about 7 nm) and amorphous phases indicated three different microstructures which can be formed in Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} system during milling process. The formed supersaturated solid solution and amorphous phases were unstable and transformed to Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound during annealing process. It is shown that, Al{sub 9}FeNi phase in Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound can decompose into Al{sub 3}Ni, Al{sub 13}Fe{sub 4} and liquid phases during a reversible peritectic reaction at 809 °C. - Highlights: • We study the effect of milling process on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} alloy. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} supersaturated solid solution phase. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} amorphous phase. • We study the thermal behaviour of Al{sub 9}FeNi/Al{sub 3}Ti compound.

Oxidation behavior of niobium aluminide intermetallics protected by aluminide and silicide diffusion coatings

International Nuclear Information System (INIS)

Li, Y.; Soboyejo, W.; Rapp, R.A.

1999-01-01

The isothermal and cyclic oxidation behavior of a new class of damage-tolerant niobium aluminide (Nb 3 Al-xTi-yCr) intermetallics is studied between 650 C and 850 C. Protective diffusion coatings were deposited by pack cementation to achieve the siliciding or aluminizing of substrates with or without intervening Mo or Ni layers, respectively. The compositions and microstructures of the resulting coatings and oxidized surfaces were characterized. The isothermal and cyclic oxidation kinetics indicate that uncoated Nb-40Ti-15Al-based intermetallics may be used up to ∼750 C. Alloying with Cr improves the isothermal oxidation resistance between 650 C and 850 C. The most significant improvement in oxidation resistance is achieved by the aluminization of electroplated Ni interlayers. The results suggest that the high-temperature limit of niobium aluminide-based alloys may be increased to 800 C to 850 C by aluminide-based diffusion coatings on ductile Ni interlayers. Indentation fracture experiments also indicate that the ductile nickel interlayers are resistant to crack propagation in multilayered aluminide-based coatings

Chemical Reduction Synthesis of Iron Aluminum Powders

Science.gov (United States)

Zurita-Méndez, N. N.; la Torre, G. Carbajal-De; Ballesteros-Almanza, L.; Villagómez-Galindo, M.; Sánchez-Castillo, A.; Espinosa-Medina, M. A.

In this study, a chemical reduction synthesis method of iron aluminum (FeAl) nano-dimensional intermetallic powders is described. The process has two stages: a salt reduction and solvent evaporation by a heat treatment at 1100°C. The precursors of the synthesis are ferric chloride, aluminum foil chips, a mix of Toluene/THF in a 75/25 volume relationship, and concentrated hydrochloric acid as initiator of the reaction. The reaction time was 20 days, the product obtained was dried at 60 °C for 2 h and calcined at 400, 800, and 1100 °C for 4 h each. To characterize and confirm the obtained synthesis products, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques were used. The results of morphology and chemical characterization of nano-dimensional powders obtained showed a formation of agglomerated particles of a size range of approximately 150 nm to 1.0 μm. Composition of powders was identified as corundum (Al2O3), iron aluminide (FeAl3), and iron-aluminum oxides (Fe0. 53Al0. 47)2O3 phases. The oxide phases formation were associated with the reaction of atmospheric concentration-free oxygen during synthesis and sintering steps, reducing the concentration of the iron aluminum phase.

Cast iron (CI) based soft magnetic BMG Ci{sub 88.3}Al{sub 2}Ga{sub 1}P{sub 4.35}B{sub 4.35}

Energy Technology Data Exchange (ETDEWEB)

Kane, S N; Lee, H J; Jeong, Y H [Department of Physics, Pohang University of Science and Technology (POSTECH), 790-784 Pohang (Korea, Republic of); Varga, L K, E-mail: varga@szfki.h [RISSPO, Hungarian Academy of Sciences, PO Box 49, 1525 Budapest (Hungary)

2009-01-01

Thermal stability, structure, and magnetic properties of bulk type Ci{sub 88.3}Al{sub 2}Ga{sub 1}P{sub 4.35}B{sub 4.35} alloy in ribbon form have been studied using differential thermal analysis, x-ray diffraction and magnetic measurements. Results reveal that crystallization peak temperature (T{sub x}) and Curie temperature (T{sub c}) of the as-cast alloy are respectively 513 and 370 deg. C. Crystallization of the specimen starts after annealing at 460 deg. C and alpha-Fe is precipitated out. Annealing at temperatures higher than 515 deg. C, produces apart from alpha-Fe, hard magnetic precipitants (Fe{sub 2}B, Fe{sub 3}B), which deteriorate the soft magnetic properties. Lowest coercive field - 9.8 A/m, highest saturation of induction - 1.55 Tesla and best losses - 0.42 W/kg (at 50 Hz and 0.4 kA/m) were obtained for as-cast specimen. Observed good soft magnetic properties of these low cost cast-iron based alloys suggest perspective applications of these soft magnetic alloys as an alternative to the conventional Fe-Si electrical steel and Mn-Zn ferrites.

Method of preparing an Al-Ti-B grain refiner for aluminium-comprising products, and a method of casting aluminium products

OpenAIRE

Brinkman, H.J.; Duszczyk, J.; Katgerman, L.

1999-01-01

The invention relates to a method of preparing an Al-Ti-B grain refiner for cast aluminium-comprising products. According to the invention the preparation is realized by mixing powders selected from the group comprising aluminium, titanium, boron, and alloys and intermetallic compounds thereof, compressing, heating in an inert environment until an exothermic reaction is initiated and cooling. It has been shown that when the grain refiner thus prepared is applied, the quality of cast products ...

Optimization of the composition and structure of heat-resistant casting aluminium alloys with additions of cerium, iron, nickel and zirconium

International Nuclear Information System (INIS)

Belov, N.A.; Lavrishchev, Yu.V.

2000-01-01

A study is made of the effect of composition and structure on mechanical properties of cast alloys of the Al-Ce-Ni-Fe-Zr system in which binary and ternary eutectics with participation of low alloyed aluminium solid solution and Al 4 Ce, Al 3 Ni and Al 9 FeNi phases are crystallized. It is found that microhardness of eutectics is heavily dependent on the volume fraction of aluminides and their dispersivity. It was shown that essential hardening of aluminium matrix can be achieved at the cost of zirconium additive in quantity of 0.6 % when using two-stage manufacturing operation. Experimental compositions of Al-10 % Ce-5% Ni-0.6 % Zr and Al-1.5 % Fe-1.5 % Ni-0.6 % Zr on the basis of ternary and binary eutectics respectively as billets essentially exceed industrial heat-resistant cast aluminium alloys AK12MMgN and AM5 as to a set of room and high-temperature mechanical properties and hot brittleness index [ru

DFT investigation on the selective complexation of Fe3+ and Al3+ with hydroxypyridinones used for treatment of the aluminium and iron overload diseases.

Science.gov (United States)

Kaviani, Sadegh; Izadyar, Mohammad; Housaindokht, Mohammad Reza

2018-03-01

The chelating agents for Al 3+ and Fe 3+ metal cations with therapeutic applications have been considered in the recent years. In designing of the hydroxypyridinones (HPOs) as the therapeutic chelating agents for iron and aluminium overload pathologies, quantum mechanical (QM) calculations are necessary for predicting the binding energies and thermodynamic parameters of the metal-HPO complexes. Three derivatives of the HPOs called 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (DFP), 3-hydroxy-4(1H)-pyridinone (HOPO) and 5-hydroxy-2-(hydroxymethyl)pyridin-4(1H)-one (P1) were investigated for complexation with Fe 3+ and Al 3+ metal ions. Because of the maximum interaction between Fe 3+ and HPOs, all HPOs form stable complexes with Fe 3+ metal ion. Moreover, it was found that [Fe-P1] 2+ is a more stable complex than [Fe-DFP] 2+ and [Fe-3,4-HOPO] 2+ in the gas phase and water, confirming that P1 is the strongest selective iron chelator. The more stability of [Fe-P1] 2+ was attributed to an intramolecular hydrogen bond formation between the hydrogen atom of NH group and the oxygen atom of CH 2 OH chain. All complexes of the HPOs with Fe 3+ and Al 3+ were formed through the oxygen atoms of the CO and OH groups of the HPO. Natural bond orbital analysis showed that the interaction of the lone pair electrons of the oxygen atom of the chelator and antibonding orbitals of the Al 3+ and Fe 3+ are important in the complex formation. Topological parameters at the bond critical points confirmed the effective interaction between the Al 3+ and Fe 3+ metal ions and HPO as well as the nature of the metal-oxygen bonds. Copyright © 2018 Elsevier Inc. All rights reserved.

Structural and functional intermetallics - an overview

International Nuclear Information System (INIS)

Varin, R.A.

2000-01-01

This overview presents the current status of the research and development of both structural and functional intermetallics. On the one hand, the discussion is focused on commercialization and existing industrial applications of intermetallics. Within this frame the applications of titanium aluminides (TiAl) for turbocharger rotors and exhaust valves in automotive industry are being discussed. Advances in the applications of TiAl alloys for the next generation of turbine blades in aerospace/aircraft segment are also presented. The entire spectrum of nickel and iron aluminide alloys developed commercially by the Oak Ridge national Laboratory (USA) and the examples of their application in various segments of industry are thoroughly discussed. Some inroads made in the application of directionally solidified (DS) multiphase niobium silicides (Nb 3 Si+Nb 5 Si 3 ) in situ intermetallic composites with the goal of pushing the service temperature envelope of turbine blades to ∼ 1200-1300 o C are also discussed. On the other hand, various topics in basic or curiosity driven research of titanium aluminides and trialuminides, iron aluminides and high temperature structural silicides are discussed. Some very recent findings on the improvements in fracture toughness and strength of titanium trialuminides and magnetic behaviour of unconventionally cold - worked iron aluminides are highlighted. The topic of functional intermetallics is limited to the systems must suitable for hydrogen storage applications. A perspective on the directions of future research and development of intermetallics is also provided. (author)

Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The performance of Al-Ti-C master alloy in refining Al-10Mg and A1-5Cu alloys was studied by using electron probe micro-analyzer (EPMA) and X-ray diffractometer (XRD) analysis.The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds.Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading.However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti(Al, Cu)2, which is responsible for the refinement fading in Al-5Cu alloy.These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.

As-cast microstructures of Ti-11 Al- xC alloys

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

Presents the investigation of as-cast microstructures of high temperature α + α2 titanium alloys matrix composites reinforced by particles and fabricated using a reaction synthesis method by XRD, OM and SEM which reveals that the matrix transformed into single phase α2 from two phases α + α2 and reinforcing phases become Ti3A1C and TiC from single phase TiC as C content increases to a critical value, and Ti3AlC precipitates during solidification processing and points out that the norphologies of TiC and Ti3AlC are of short-lath shape and near spherical shape, respectively, and lattice parameters of matrix α2 increase with the increasing of C content, but the lattice parameter of reinforcing phase TiC is lower than standard lattice parameter of TiC due to the C defection in TiC.

The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

International Nuclear Information System (INIS)

Schuon, S.R.

1982-01-01

The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life

Effect of Mn and AlTiB Addition and Heattreatment on the Microstructures and Mechanical Properties of Al-Si-Fe-Cu-Zr Alloy.

Science.gov (United States)

Yoo, Hyo-Sang; Kim, Yong-Ho; Lee, Seong-Hee; Son, Hyeon-Taek

2018-09-01

The microstructure and mechanical properties of as-extruded Al-0.1 wt%Si-0.2 wt%Fe- 0.4 wt%Cu-0.04 wt%Zr-xMn-xAlTiB (x = 1.0 wt%) alloys under various annealing processes were investigated and compared. After the as-cast billets were kept at 400 °C for 1 hr, hot extrusion was carried out with a reduction ratio of 38:1. In the case of the as-extruded Al-Si-Fe-Cu-Zr alloy at annealed at 620 °C, large equiaxed grain was observed. When the Mn content is 1.0 wt%, the phase exhibits a skeleton morphology, the phase formation in which Mn participated. Also, the volume fraction of the intermetallic compounds increased with Mn and AlTiB addition. For the Al-0.1Si-0.2Fe-0.4Cu-0.04Zr alloy with Mn and AlTiB addition from 1.0 wt%, the ultimate tensile strength increased from 100.47 to 119.41 to 110.49 MPa. The tensile strength of the as-extruded alloys improved with the addition of Mn and AlTiB due to the formation of Mn and AlTiB-containing intermetallic compounds.

Grain refining efficiency of Al-Ti-C alloys

International Nuclear Information System (INIS)

Birol, Yuecel

2006-01-01

The problems associated with boride agglomeration and the poisoning effect of Zr in Zr-bearing alloys have created a big demand for boron-free grain refiners. The potential benefits of TiC as a direct nucleant for aluminium grains have thus generated a great deal of interest in TiC-bearing alloys in recent years. In Al-Ti-C grain refiners commercially available today, Al 3 Ti particles are introduced into the melt along with the TiC particles. Since the latter are claimed to nucleate α-Al directly, it is of great technological interest to see if reducing the Ti:C ratio further, i.e., increasing the C content of the grain refiner, will produce an increase in the grain refining efficiency of these alloys. A series of grain refiner samples with the Ti concentration fixed at 3% and a range of C contents between 0 and 0.75 were obtained by appropriately mixing an experimental Al-3Ti-0.75C alloy with Al-10Ti alloy and commercial purity aluminium. The grain refining efficiency of these grain refiners was assessed to investigate the role of the insoluble TiC and the soluble Al 3 Ti particles. The optimum chemistry for the Al-Ti-C grain refiners was also identified

Grain refining efficiency of Al-Ti-C alloys

Energy Technology Data Exchange (ETDEWEB)

Birol, Yuecel [Materials Institute, Marmara Research Center, TUBITAK, 41470 Gebze, Kocaeli (Turkey)]. E-mail: yucel.birol@mam.gov.tr

2006-09-28

The problems associated with boride agglomeration and the poisoning effect of Zr in Zr-bearing alloys have created a big demand for boron-free grain refiners. The potential benefits of TiC as a direct nucleant for aluminium grains have thus generated a great deal of interest in TiC-bearing alloys in recent years. In Al-Ti-C grain refiners commercially available today, Al{sub 3}Ti particles are introduced into the melt along with the TiC particles. Since the latter are claimed to nucleate {alpha}-Al directly, it is of great technological interest to see if reducing the Ti:C ratio further, i.e., increasing the C content of the grain refiner, will produce an increase in the grain refining efficiency of these alloys. A series of grain refiner samples with the Ti concentration fixed at 3% and a range of C contents between 0 and 0.75 were obtained by appropriately mixing an experimental Al-3Ti-0.75C alloy with Al-10Ti alloy and commercial purity aluminium. The grain refining efficiency of these grain refiners was assessed to investigate the role of the insoluble TiC and the soluble Al{sub 3}Ti particles. The optimum chemistry for the Al-Ti-C grain refiners was also identified.

Electronic Structures and Bonding Properties of Ti2AlC and Ti3AlC2

Institute of Scientific and Technical Information of China (English)

MIN Xinmin; REN Yi

2007-01-01

The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SixAl1-x C has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al3p.

Microstructure and mechanical properties of in situ casting TiC/Ti6Al4V composites through adding multi-walled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ya, Bin; Zhou, Bingwen; Yang, Hongshuo; Huang, Bingkun; Jia, Fei; Zhang, Xingguo, E-mail: zxgwj@dlut.edu.cn

2015-07-15

Highlights: • Adding MWCNTs in situ casting fabricating TiC/Ti6Al4V composites is first reported. • The solidification process of in situ casting TiC/Ti6Al4V composites is discussed. • Microstructure shows remarkable correlations with adding MWCNTS. • Strength and plasticity show remarkable correlations with adding MWCNTs. - Abstract: In this study, multi-walled carbon nanotubes (MWCNTs) were added as carbon sources to fabricate in situ casting TiC/Ti6Al4V (TC4) composites. The effects of MWCNTs on the microstructure and mechanical properties are studied. The composites are analyzed by X-ray diffraction, field-emission scanning electron microscope and electron probe microanalysis. The fracture behavior of TiC/TC4 composites are also studied. Smaller size of TiC particles and grain compared with TC4-graphite composites can be observed. The tensile strength of TC4-MWCNTs composites is about 1110.1 MPa, which is higher than that of TC4-graphite composites, about 1003.6 MPa. Fracture behavior also was changed by adding MWCNTs in situ casting TiC/TC4 composites.

Influence of Iron in AlSi10MgMn Alloy

Directory of Open Access Journals (Sweden)

Žihalová M.

2014-12-01

Full Text Available Presence of iron in Al-Si cast alloys is common problem mainly in secondary (recycled aluminium alloys. Better understanding of iron influence in this kind of alloys can lead to reduction of final castings cost. Presented article deals with examination of detrimental iron effect in AlSi10MgMn cast alloy. Microstructural analysis and ultimate tensile strength testing were used to consider influence of iron to microstructure and mechanical properties of selected alloy.

PHASE CONSTITUENTS AND MICROSTRUCTURE OF Ti3Al/Fe3Al + TiN/TiB2 COMPOSITE COATING ON TITANIUM ALLOY

OpenAIRE

JIANING LI; CHUANZHONG CHEN; CUIFANG ZHANG

2011-01-01

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be...

Grain refining of Al-4.5Cu alloy by adding an Al-30TiC master alloy

Energy Technology Data Exchange (ETDEWEB)

Sato, Kazuaki [Toyota Motor Corp., Shizuoka (Japan). Materials Engineering Div. III; Flemings, M.C. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering

1998-06-01

A particulate Al-30 wt pct TiC composite was employed as a grain refiner for the Al-4.5 wt pct Cu alloy. The composite contains submicron TiC particles. The addition of the TiC grain refiner to the metal alloy in the amount of 0.1 Ti wt pct effected a remarkable reduction in the average grain size in Al-4.5 wt pct Cu alloy castings. With the content of over 0.2 Ti wt pct, the grain refiner maintained its refining effectiveness even after a 3,600-second holding time at 973 K. The TiC particles in the resulting castings were free of interfacial phases. It is concluded that the TiC are the nucleating agents and that they are resistant to the fading effect encountered with most grain refiners.

Hardness and Wear Resistance of TiC-Fe-Cr Locally Reinforcement Produced in Cast Steel

Directory of Open Access Journals (Sweden)

Olejnik E.

2016-06-01

Full Text Available In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy, using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ball-on-disc wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the composite zone was five times lower than chromium white cast iron containing 20 % Cr.

TiC Reinforcement Composite Coating Produced Using Graphite of the Cast Iron by Laser Cladding

Directory of Open Access Journals (Sweden)

Yanhui Liu

2016-09-01

Full Text Available In this study, a TiC-reinforced composite coating was produced to improve the wear resistance of a pearlite matrix grey iron using a pre-placed Ti powder by laser cladding. Results of scanning electron microscopy (SEM, X-ray diffractometer (XRD, and energy dispersive X-ray spectroscopy (EDS confirmed that the coating was composed of TiC particles and two kinds of α-Fe phase. The fine TiC particles were only a few microns in size and uniformly distributed on the matrix phase in the composite coating. The microstructure characteristic of the composite coating resulted in the microhardness rising to about 1000 HV0.3 (China GB/T 4342-1991 and the wear resistance significantly increased relative to the substrate. In addition, the fine and homogeneous solidification microstructure without graphite phase in the transition zone led to a good metallurgical bonding and transition between the coating and the substrate. It was of great significance for the cast iron to modify the surface and repair surface defects or surface damage.

TiC Reinforcement Composite Coating Produced Using Graphite of the Cast Iron by Laser Cladding.

Science.gov (United States)

Liu, Yanhui; Qu, Weicheng; Su, Yu

2016-09-30

In this study, a TiC-reinforced composite coating was produced to improve the wear resistance of a pearlite matrix grey iron using a pre-placed Ti powder by laser cladding. Results of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and energy dispersive X-ray spectroscopy (EDS) confirmed that the coating was composed of TiC particles and two kinds of α -Fe phase. The fine TiC particles were only a few microns in size and uniformly distributed on the matrix phase in the composite coating. The microstructure characteristic of the composite coating resulted in the microhardness rising to about 1000 HV0.3 (China GB/T 4342-1991) and the wear resistance significantly increased relative to the substrate. In addition, the fine and homogeneous solidification microstructure without graphite phase in the transition zone led to a good metallurgical bonding and transition between the coating and the substrate. It was of great significance for the cast iron to modify the surface and repair surface defects or surface damage.

High purity Fe3O4 from Local Iron Sand Extraction

Science.gov (United States)

Gunanto, Y. E.; Izaak, M. P.; Jobiliong, E.; Cahyadi, L.; Adi, W. A.

2018-04-01

Indonesia has a long coastline and is rich with iron sand. The iron sand is generally rich in various elements such as iron and titanium. One of the products processing of the iron sand mineral is iron (II) (III) oxide (magnetite Fe3O4). The stages of purification process to extracting magnetite phase and discarding the other phases has been performed. Magnetite phase analysis of ironsand extraction retrieved from Indonesia have been investigated. The result of analysis element of iron sand shows that it consists of majority Fe around 65 wt%. However, there are still 17 impurities such as Ti, Al, Ce, Co, Cr, Eu, La, Mg, Mn, Na, Sc, Sm, Th, V, Yb, and Zn. After extraction process, Fe element content increases up to 94%. The iron sand powder after milling for 10 hours and separating using a magnetic separator, the iron sand powders are dissolved in acid chloride solution to form a solution of iron chloride, and this solution is sprinkled with sodium hydroxide to obtain fine powders of Fe3O4. The fine powders which formed were washed with de-mineralization water. The X-ray diffraction pattern shows that the fine powders have a single phase of Fe3O4. The analysis result shows that the sample has the chemical formula: Fe3O4 with a cubic crystal system, space group: Fd-3m and lattice parameters: a = b = c = 8.3681 (1) Å, α = β = γ = 90°. The microstructure analysis shows that the particle of Fe3O4 homogeneously shaped like spherical. The magnetic properties using vibrating sample magnetometer shows that Fe3O4 obtained have ferromagnetic behavior with soft magnetic characteristics. We concluded that this purification of iron sand had been successfully performed to obtain fine powders of Fe3O4 with high purity.

Corrosion behavior of Fe3Al intermetallics with addition of lithium, cerium and nickel in 2.5 % SO2+N2 at 900 °C

Directory of Open Access Journals (Sweden)

González-Rodríguez, J. G.

2012-12-01

Full Text Available The corrosion behavior of Fe3Al-type intermetallic alloys with addition of 1 at. % cerium, lithium and nickel at high temperature has been studied. The various alloys were exposed to an environment composed of 2.5 % SO2+N2 at 900 °C for 48 h. For all the intermetallic tested, the corrosion kinetics showed a parabolic behavior. The alloy, which showed less corrosion rate, was the Fe3AlNi alloy, being Fe3AlCeLi the alloy with the highest corrosion rate. For the various alloys, energy dispersive X-ray spectroscopy analysis, EDS, on the developed scale only detected aluminum, oxygen, and traces of iron and cerium, suggesting the formation of alumina as main component. The intermetallic alloys showed oxide cracking and spalling. The intermetallic chemical composition played an important role in defining the oxide scale morphology and the extent of damage.Se estudió el comportamiento a la corrosión a alta temperatura de intermetálicos tipo Fe3Al con adición de 1at. % de cerio, litio y níquel. Las diferentes aleaciones fueron expuestas bajo un ambiente compuesto de 2,5 % SO2+N2 a 900 °C durante 48 h. Para todos los intermetálicos ensayados, la cinética de corrosión presentó un comportamiento parabólico. La aleación que mostró la menor velocidad de corrosión fue el intermetálico Fe3AlNi, siendo el intermetálico Fe3AlCeLi el de mayor velocidad de corrosión. Los análisis mediante espectroscopía de dispersión de rayos X, EDS, sobre la costra formada identificaron únicamente aluminio, oxígeno y trazas de hierro y cerio, lo que sugiere la formación de alúmina como el componente principal. Los intermetálicos mostraron agrietamiento y desprendimiento de la costra de óxido. La composición química de los intermetálicos tuvo un papel importante en la definición de la morfología del óxido formado y el grado de daño.

A simple stir casting technique for the preparation of in situ Fe-aluminides reinforced Al-matrix composites

Directory of Open Access Journals (Sweden)

Susanta K. Pradhan

2016-09-01

Full Text Available This article presents a simple stir casting technique for the development of Fe-aluminides particulate reinforced Al-matrix composites. It has been demonstrated that stirring of super-heated Al-melt by a mild steel plate followed by conventional casting and hot rolled results in uniform dispersion of in situ Al13Fe4 particles in the Al matrix; the amount of reinforcement is found to increase with increasing melt temperature. With reference to base alloy, the developed composite exhibits higher hardness and improved tensile strength without much loss of ductility; since, composite like base alloy undergoes ductile mode of fracture.

Investigation on effect of iron and corundum content on corrosion resistance of the NiFe-Al2O3 coatings

International Nuclear Information System (INIS)

Starosta, R.; Zielinski, A.

1999-01-01

The alloy NiFe and composite NiFe-Al 2 O 3 coatings, obtained by electrodeposition on the base of cast iron, were investigated. The iron content in alloy coatings was dependent on iron content in galvanic bath, and was estimated by means of X-ray microanalysis at 18.5 wt. pct. and 41.2 wt. pct. No existence of ordered Ni 3 Fe phase was found by diffraction technique. Both potentiodynamic and impedance measurements disclosed that a presence of Al 2 O 3 or increasing iron content in the layer caused the decrease in corrosion resistance. (author)

Mechanical Properties of Nano structured TiC-FeAl Hard Materials

International Nuclear Information System (INIS)

Shon, In-Jin; Jo, Hyoung-Gon; Kim, Byung-Su; Yoon, Jin-Kook; Hong Kyung-Tae

2015-01-01

For the formation of cemented Tic composite, Co or Ni is added as a binder. However, the high cost and low hardness of Co or Ni as binder and the low corrosion resistance of Tic-Co and Tic-Ni composite have generated interest to find alternative binder materials. It has been reported that FeAl show higher oxidation resistance and hardness as well as low cost compared to Co or Ni. Highly dense nanocrystalline Tic and Tic-FelAl with a relative density of up to 100% were obtained within 2 min by PCAS(pulsed current activated sintering) under the condition of 80MPa and up to 1300. The effect of FeAl addition of FeAl on the consolidation, the microstructure and the mechanical properties (hardness and fracture toughness) of TiC were investigated. The fracture toughness of TiC greatly increases without great decrease of the hardness by addition of FeAl. Not only fracture toughness but also hardness values of TiC-10vol.%FeAl were higher than those of TiC-10vol.%Fe, TiC-10vol.%Ni and TiC-10vol.%Co.

A study on wear resistance and microcrack of the Ti3Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Li Jianing; Chen Chuanzhong; Squartini, Tiziano; He Qingshan

2010-01-01

Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti 3 Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti 3 Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti 3 Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti 3 Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

Tailoring ultrafine grained and dispersion-strengthened Ti2AlC/TiAl ...

Indian Academy of Sciences (India)

and Ti-Al pre-alloyed powders at low temperature of 1150◦C. The composite mainly consisted ... Metal–matrix composites; mechanical properties; microstructures; sintering. 1. Introduction γ-TiAl-based intermetallic alloys have been extensively.

Micromechanisms of fracture and fatigue in Ti3Al based and TiAl based intermetallics

International Nuclear Information System (INIS)

James, A.W.; Chave, R.A.; Hippsley, C.A.; Bowen, P.

1993-01-01

Micromechanisms of fracture and fatigue crack growth resistance in specific Ti 3 Al based and TiAl based intermetallics are reviewed. Effects of test temperature, environment and microstructure on crack growth resistance are considered in detail for several Ti 3 Al and Ti'Al based intermetallic systems under development. The implications of these studies for the structural reliability of these materials is also addressed briefly. (orig.)

Morphological evolution of primary TiC carbide in laser clad TiC reinforced FeAl intermetallic composite coating

Institute of Scientific and Technical Information of China (English)

陈瑶; 王华明

2003-01-01

The novel rapidly solidified TiC/FeAl composite coatings were fabricated by laser cladding on the substrate of 1Cr18Ni9Ti stainless steel, particular emphasis has been placed on the growth morphologies of TiC carbide and its growth mechanism under a constant solidification conditions. Results show that the growth morphology of TiC carbide strongly depends upon the nucleation process and mass transportation process of TiC forming elements in laser melt pool. With increasing amount of titanium and carbon in melt pool, the growth morphology of TiC carbide changes from block-like to star-like and well-developed dendrite. As the amount of titanium and carbon increases further, TiC carbide particles are found to be irregular polyhedral block. Although the growth morphologies of TiC are various,their advancing fronts are all faceted, illustrating that TiC carbide grows by the mechanism of lateral ledge growth.

Formation of Al{sub 2}O{sub 3}/FeAl coatings on a 9Cr-1Mo steel, and corrosion evaluation in flowing Pb-17Li loop

Energy Technology Data Exchange (ETDEWEB)

Majumdar, Sanjib, E-mail: sanjib@barc.gov.in [High Temperature Materials Development Section, Materials Processing & Corrosion Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Paul, Bhaskar [High Temperature Materials Development Section, Materials Processing & Corrosion Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Chakraborty, Poulami [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Kishor, Jugal; Kain, Vivekanand [High Temperature Materials Development Section, Materials Processing & Corrosion Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Dey, Gautam Kumar [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Materials Group, Bhabha Atomic Research Centre, Trombay, Mumbai (India)

2017-04-01

Iron aluminide coating layers were formed on a ferritic martensitic grade 9Cr-1Mo (P 91) steel using pack aluminizing process. The formation of different aluminide compositions such as orthorhombic-Fe{sub 2}Al{sub 5}, B2-FeAl and A2-Fe(Al) on the pack chemistry and heat treatment conditions have been established. About 4–6 μm thick Al{sub 2}O{sub 3} scale was formed on the FeAl phase by controlled heat treatment. The corrosion tests were conducted using both the FeAl and Al{sub 2}O{sub 3}/FeAl coated specimens in an electro-magnetic pump driven Pb-17Li Loop at 500 °C for 5000 h maintaining a flow velocity of 1.5 m/s. The detailed characterization studies using scanning electron microscopy, back-scattered electron imaging and energy dispersive spectrometry revealed no deterioration of the coating layers after the corrosion tests. Self-healing oxides were formed at the cracks generated in the aluminide layers during thermal cycling and protected the base alloy (steel) from any kind of elemental dissolution or microstructural degradation. - Highlights: •Al{sub 2}O{sub 3}/FeAl coating produced on P91 steel by pack aluminizing and heat treatment. •Corrosion tests of coated steel conducted in flowing Pb-17Li loop at 500 °C for 5000 h. •Coating was protective against molten metal corrosion during prolonged exposure. •Self-healing protective oxides formed in the cracks generated in aluminide layers.

Oxidation Kinetics of Cast TiAl3

Science.gov (United States)

Smialek, J. L.; Humphrey, D. L.

1992-01-01

The isothermal oxidation kinetics of the TiAl3 compound over a wide temperature range is documented, and these rates are related to exclusive alpha-Al2O3 scale growth. The specific weight change vs time curves are shown. Two abnormalities are immediately apparent. One is that a rapid initial uptake of oxygen occurs at times less than 5 h, followed by a lower oxidation rate at longer times, for tests at 900 C and below. The other is that the final weight changes for the 700, 800, and 900 C tests are not in the sequence expected with respect to temperature. Isothermal oxidation of drop cast TiAl above 1000 C was found to exhibit parabolic oxidation controlled by protective alpha-Al2O3 scale formation. TiAl is the only phase in the binary Ti-Al system that forms exclusive scales of alpha-Al2O3 in isothermal oxidation. High anomalous rates at short times and at temperatures below 1000 C resulted from the internal oxidation of a second phase of aluminum.

A study on wear resistance and microcrack of the Ti{sub 3}Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

Energy Technology Data Exchange (ETDEWEB)

Li Jianing, E-mail: ljnljn1022@163.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Chen Chuanzhong [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Squartini, Tiziano [INFM-Department of Physics, Siena University, Siena 53100 (Italy); He Qingshan [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China)

2010-12-15

Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti{sub 3}Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti{sub 3}Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti{sub 3}Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti{sub 3}Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

Wetting behavior of liquid Fe-C-Ti alloys on sapphire

International Nuclear Information System (INIS)

Gelbstein, M.; Froumin, N.; Frage, N.

2008-01-01

Wetting behavior in the (Fe-C-Ti)/sapphire system was studied at 1823 K. The wetting angle between sapphire and Fe-C alloys is higher than 90 deg. (93 deg. and 105 deg. for the alloys with 1.4 and 3.6 at.% C, respectively). The presence of Ti improves the wetting of the iron-carbon alloys, especially for the alloys with carbon content of 3.6 at.%. The addition of 5 at.% Ti to Fe-3.6 at.% C provides a contact angle of about 30 deg., while the same addition to Fe-1.4 at.% C decreases the wetting angle to 70 deg. only. It was established that the wetting in the systems is controlled by the formation of a titanium oxicarbide layer at the interface, which composition and thickness depend on C and Ti contents in the melt. The experimental observations are well accounted for by a thermodynamic analysis of the Fe-Ti-Al-O-C system

Method of manufacturing iron aluminide by thermomechanical processing of elemental powders

Science.gov (United States)

Deevi, Seetharama C.; Lilly, Jr., A. Clifton; Sikka, Vinod K.; Hajaligol, Mohammed R.

2000-01-01

A powder metallurgical process of preparing iron aluminide useful as electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 20 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1 % rare earth metal, .ltoreq.1% oxygen, and/or .ltoreq.3% Cu. The process includes forming a mixture of aluminum powder and iron powder, shaping the mixture into an article such as by cold rolling the mixture into a sheet, and sintering the article at a temperature sufficient to react the iron and aluminum powders and form iron aluminide. The sintering can be followed by hot or cold rolling to reduce porosity created during the sintering step and optional annealing steps in a vacuum or inert atmosphere.

The solidification and structure of Al-17wt.%Si alloy modified with intermetallic phases containing Ti and Fe

Directory of Open Access Journals (Sweden)

J. Piątkowski

2011-10-01

Full Text Available The article describes the process of casting and solidification of Al-17wt.%Si alloy that have been modified with composite powdercontaining the intermetallic phases of Ti and Fe. The chemical and phase composition of the applied modifier was described with thefollowingformula:FeAlx–TiAlx–Al2O3. Applying the method of thermal analysis ATD, the characteristic parameters of the solidificationprocess were determined, and exo-and endothermic effects of the modifying powder on the run of the silumin solidification curves wereobserved. By the methods of light, scanning, and X-ray microscopy, the structure of alloy and the chemical composition of the dispersionhardening precipitates were examined. A change in the morphology of Al-Si eutectic from the lamellar to fibrous type was reportedtogether with changes in the form of complex eutectics of an Al-Si-Ti and Al-Si-Fe type and size reduction of primary silicon crystals.

Microstructural characteristics of Al-alloyed austempered ductile irons

International Nuclear Information System (INIS)

Kiani-Rashid, A.R.; Edmonds, D.V.

2009-01-01

Microstructural development after austempering ductile irons containing 0.48% and 4.88%Al has been studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental irons were made by green sand casting and gravity die casting. After austenitising at 920 deg. C for 90 min, an austempering treatment at 400 deg. C for times up to 100 min resulted in microstructures consisting of carbide-free bainitic ferrite with considerable amounts of high carbon retained austenite.

Structure, thermal and mechanical properties of in situ Al-based metal matrix composite reinforced with Al2O3 and TiC submicron particles

International Nuclear Information System (INIS)

Yu Peng; Mei Zhi; Tjong, S.C.

2005-01-01

We report herein the structure and characterization of in situ Al-based metal matrix composites (MMCs) prepared from the Al-10 wt.% TiO 2 and Al-10 wt.% TiO 2 -1.5 wt.% C systems via hot isostatic pressing (HIP) at 1000 deg C and 100 MPa. The structure, morphology and thermal behavior of HIPed samples were studied by means of the X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicated that fined Al 2 O 3 particles and large intermetallic Al 3 Ti plates were in situ formed in the Al-10 wt.% TiO 2 sample during HIPing. However, the introduction of C to the Al-TiO 2 system was beneficial to eliminate large intermetallic Al 3 Ti plates. In this case, Al 2 O 3 and TiC submicron particles were in situ formed in the Al-10 wt.% TiO 2 -1.5 wt.% C sample. Three-point-bending test showed that the strength and the strain-at-break of the HIPed Al-10 wt.% TiO 2 -1.5 wt.% C sample were significantly higher than those of its Al-10 wt.% TiO 2 counterpart. The improvement was derived from the elimination of bulk Al 3 Ti intermetallic plates and from the formation of TiC submicron particles. DSC measurements and thermodynamic analyses were carried out to reveal the reaction formation mechanisms of in situ reinforcing phases. The DSC results generally correlated well with the theoretical predictions. Finally, the correlation between the structure-property relationships of in situ composites is discussed

Influence of Al grain structure on Fe bearing intermetallics during DC casting of an Al-Mg-Si alloy

OpenAIRE

Kumar, S.; O'Reilly, K.A.Q.

2016-01-01

207 mm diameter direct chill (DC) cast billets of 6063 aluminium-magnesium-silicon (Al-Mg-Si) alloy were produced with various different primary aluminium (α-Al) grain structures including feathery-dendrites, equiaxed-dendrites and equiaxed-globular morphologies. To control the α-Al grain structure (grain morphology and grain size) an intensive shearing melt conditioning technique and Al-5Ti-1B grain refiner were used. For the first time, due to the variety of controlled microstructures produ...

Evolution of Iron-containing Compounds in Al-Cu Alloys during Heat Treatment

Directory of Open Access Journals (Sweden)

Liu Kun

2016-01-01

Full Text Available The evolution of iron-containing compounds in Al-Cu 206 cast alloy during solution treatment has been investigated. Results show that platelet β-Fe and Chinese script α-Fe are the two iron-containing compounds in as-cast condition. Little change is observed on β-Fe during solution treatment. However, fine blocky post β-Fe begins to form on α-Fe when solution treated at 520°C for 8hrs. When soaking time is extended to 24 hrs, α–Fe is found to decompose to fine branches while post β-Fe present as clusters on these branches. Al-Cu-Mg-Si Q phase is observed to form at the edge of decomposed α-Fe, possibly the result of Si from decomposed α-Fe.

Constituent phase diagrams of the Al-Cu-Fe-Mg-Ni-Si system and their application to the analysis of aluminium piston alloys

Energy Technology Data Exchange (ETDEWEB)

Belov, N.A. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation); Eskin, D.G. [Netherlands Institute for Metals Research, Rotterdamseweg 137, 2628AL Delft (Netherlands)]. E-mail: deskin@nimr.nl; Avxentieva, N.N. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation)

2005-10-15

The evaluation of phase equilibria in quinary systems that constitute the commercially important Al-Cu-Fe-Mg-Ni-Si alloying system is performed in the compositional range of casting alloys by means of metallography, electron probe microanalysis, X-ray diffractometry, differential scanning calorimetry, and by the analysis of phase equilibria in the constituent systems of lesser dimensionality. Suggested phase equilibria are illustrated by bi-, mono- and invariant solidification reactions, polythermal diagrams of solidification, distributions of phase fields in the solid state, and isothermal and polythermal sections. Phase composition of as-cast alloys is analyzed in terms of non-equilibrium solidification. It is shown that the increase in copper concentration in piston Al-Si alloys results in the decrease in the equilibrium solidus from 540 to 505 deg C. Under non-equilibrium solidification conditions, piston alloys finish solidification at {approx}505 deg C. Iron is bound in the quaternary Al{sub 8}FeMg{sub 3}Si{sub 6} phase in low-iron alloys and in the ternary Al{sub 9}FeNi and Al{sub 5}FeSi phases in high-iron alloys.

Cast AlSi9Cu4 alloy with hybride strenghtened by Fe{sub x}Al{sub y}-Al{sub 2}O{sub 3} composite powder

Energy Technology Data Exchange (ETDEWEB)

Piatkowski, J [Department of Materials Technology, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice (Poland); Formanek, B, E-mail: jaroslaw.piatkowski@polsl.pl, E-mail: boleslaw.formanek@polsl.pl [Department of Materials Science, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice (Poland)

2011-05-15

The main objective of the study was to develop a technology of dispersion strenghtened hypoeutectic Al-Si alloy. The article presented the materials and technology conception for producing aluminium matrix composite AlSi9Cu4Fe alloy with hybride reinforcement of Al{sub x}Fe{sub y} intermetallic and aluminium oxide powders. Composite powder obtained in mechanical agllomerisation mixture of elemental powders. Changes in the structure were confirmed by TA and ATD thermal analyses plotting the solidification curves, which showed a decrease in temperature T{sub liq} compared to the unmodified alloy and an exothermic effect originating from the crystallisation of eutectics with alloying elements. The examinations carried out by SEM and BSE as well as the determination of local chemical composition by EDX technique have characterised the structure of the alloy as containing some binary Al-Si-Al-Cu and Al-Fe eutectics and multicomponent eutectics.

Grindability of cast Ti-6Al-4V alloyed with copper.

Science.gov (United States)

Watanabe, Ikuya; Aoki, Takayuki; Okabe, Toru

2009-02-01

This study investigated the grindability of cast Ti-6Al-4V alloyed with copper. The metals tested were commercially pure titanium (CP Ti), Ti-6Al-4V, experimental Ti-6Al-4V-Cu (1, 4, and 10 wt% Cu), and Co-Cr alloy. Each metal was cast into five blocks (3.0 x 8.0 x 30.0 mm(3)). The 3.0-mm wide surface of each block was ground using a hand-piece engine with an SiC wheel at four circumferential speeds (500, 750, 1000, and 1250 m/min) at a grinding force of 100 g. The grindability index (G-index) was determined as volume loss (mm(3)) calculated from the weight loss after 1 minute of grinding and the density of each metal. The ratio of the metal volume loss and the wheel volume loss was also calculated (G-ratio, %). Data (n = 5) were statistically analyzed using ANOVA (alpha= 0.05). Ti-6Al-4V and the experimental Ti-6Al-4V-Cu alloys exhibited significantly (p grindability of some of the resultant Ti-6Al-4V-Cu alloys.

Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

Science.gov (United States)

Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

2005-05-01

It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. (c) 2005 Wiley Periodicals, Inc.

Iron aluminide useful as electrical resistance heating elements

Science.gov (United States)

Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

1997-04-15

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

Investigations of Ferritic Nodular Cast Iron Containing About 5-6% Aluminium

Directory of Open Access Journals (Sweden)

Soiński M.S.

2016-12-01

Full Text Available The work presents results of investigations concerning the production of cast iron containing about 5-6% aluminium, with the ferritic matrix in the as-cast state and nodular or vermicular graphite precipitates. The examined cast iron came from six melts produced under the laboratory conditions. It contained aluminium in the amount of 5.15% to 6.02% (carbon in the amount of 2.41% to 2.87%, silicon in the amount of 4.50% to 5.30%, and manganese in the amount of 0.12% to 0.14%. After its treatment with cerium mixture and graphitization with ferrosilicon (75% Si, only nodular and vermicular graphite precipitates were achieved in the examined cast iron. Moreover, it is possible to achieve the alloy of pure ferritic matrix, even after the spheroidizing treatment, when both the aluminium and the silicon occur in cast iron in amounts of about 5.2÷5.3%.

Influence of Sr, Fe and Mn content and casting process on the microstructures and mechanical properties of AlSi7Cu3 alloy

Energy Technology Data Exchange (ETDEWEB)

Li, Zaidao [Laboratoire de Mécanique de Lille (LML), FRE 3723, Ecole Centrale de Lille, 59651 Villeneuve d' Ascq (France); Unité Matériaux et Transformations, UMR CNRS 8207, Univ. Lille 1, 59655 Villeneuve d' Ascq (France); Limodin, Nathalie; Tandjaoui, Amina; Quaegebeur, Philippe [Laboratoire de Mécanique de Lille (LML), FRE 3723, Ecole Centrale de Lille, 59651 Villeneuve d' Ascq (France); Osmond, Pierre [PSA Peugeot Citröen, Direction de la Recherche et de l' Innovation Automobile, Route de Gisy-78943, Vélizy-Villacoublay Cedex (France); Balloy, David [Unité Matériaux et Transformations, UMR CNRS 8207, Univ. Lille 1, 59655 Villeneuve d' Ascq (France)

2017-03-24

The effects of Strontium (Sr), Iron (Fe) and Manganese (Mn) additions, casting process (i.e., cooling rate) on the microstructures and mechanical properties of AlSi7Cu3 alloy were investigated. 2D and 3D metallographic and image analysis have been performed to measure the microstructural changes occurring at different Sr, Fe and Mn levels and casting process. The evolution of mechanical properties of the alloys has been monitored by Brinell and Vickers hardness measurement and tensile tests. Addition of Sr slightly refines the eutectic silicon particles but it also introduces more pores. The combined addition of Fe and Mn induces an increase of Fe-rich intermetallic compounds which include both α-Al{sub 15}(Fe,Mn){sub 3}Si{sub 2} and β-Al{sub 5}FeSi phase, while the volume fraction of porosity decreases with the Fe and Mn content increase. The secondary dendrite arm spacing slightly decreases with the addition of Sr, Fe and Mn alloying elements.

Processing and application properties of silicon-doped titanium aluminides; Formgebungs- und Anwendungseigenschaften silizidhaltiger TiAl-Legierungen

Energy Technology Data Exchange (ETDEWEB)

Fanta, G. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Werkstofforschung

2001-07-01

Submicrocrystalline intermetallic/ceramic composites based on the system Ti-Al-Si are prepared by mechanical alloying and subsequent powder consolidation. Finely dispersed silicides prevent coarsening of the {gamma}-TiAl matrix during hot-forming. Therefore, the deformation temperatures can be reduced by about 200 C compared to conventional titanium aluminides. After a subsequent coarsening heat treatment, creep properties comparable to those of conventional TiAl based alloys (1.10{sup -9} s{sup -1} at 700 C) are achieved. This study demonstrates that microstructure design allows for favorable processing properties without compromises regarding the desired application properties. (orig.) [German] Zur Untersuchung des technischen Anwendungspotenzials submikrokristalliner Werkstoffe werden silizidhaltige {gamma}-TiAl-Basislegierungen durch Hochenergiemahlen und heissisostatisches Pressen hergestellt. Bei der industriellen Formgebung ermoeglicht die durch Silizide stabilisierte feine Mikrostruktur eine deutliche Temperaturabsenkung von 200 C im Vergleich zu den fuer Titanaluminide ueblichen Prozesstemperaturen. Nach einer anschliessend durchgefuehrten Gefuegeumwandlung werden Kriechgeschwindigkeiten gemessen, die mit 1.10{sup -9} s{sup -1} bei 700 C im Bereich der Werte schmelzmetallurgisch hergestellter TiAl-Legierungen liegen. Eine gezielte Mikrostrukturgestaltung ermoeglicht somit eine deutliche Verbesserung der Umformeigenschaften unter Beibehaltung der guenstigen Eigenschaften fuer Hochtemperaturanwendungen. (orig.)

Morphology of intermetallic phases in Al-Si cast alloys and their fracture behaviour

Directory of Open Access Journals (Sweden)

Lenka Hurtalová

2015-03-01

Full Text Available Applications of Al-Si cast alloys in recent years have increased especially in the automotive industry (dynamic exposed cast, en-gine parts, cylinder heads, pistons and so on. Controlling the microstructure of secondary aluminium cast alloys is very important, because these alloys contain more additional elements that form various intermetallic phases in the structure. Therefore, the contribution is dealing with the valuation type of intermetallic phases and their identification with using optical and scanning microscopy. Some of the intermetallic phases could be identified on the basis of morphology but some of them must be identified according EDX analysis. The properties of alu-minium alloy are affected by morphology of intermetallic phases and therefore it is necessary to study morphology and its fracture behav-iour. The present work shows morphology and typical fracture behaviour as the most common intermetallic phases forming in Al-Si alloys.

Grain refinement of Al wrought alloys with newly developed AlTiC master alloys; Kornfeinung von Al-Knetlegierungen mit neu entwickelten AlTiC-Vorlegierungen

Energy Technology Data Exchange (ETDEWEB)

Schneider, W. [Vereinigte Aluminium-Werke AG, Bonn (Germany). Forschung und Entwicklung

2000-10-01

AlTiC master alloys are a new grain refiner type to produce an equiaxed grain structure of cast extrusion and rolling ingots. These master alloys contain Ti carbides which act as nucleants of the {alpha} solid solution during solidification. The TiC content is lower than the TiB{sub 2} content of the industrial proved AlTiB master alloys. Benefits of the AlTiC master alloys are the low agglomeration tendency of the Ti carbides in the melt and that no Zr poisoning takes place. Despite of the low Ti carbide content the grain refinement performance can be very efficient, if low melt temperatures during casting will be used and as result of this a sufficient constitutional supercooling at the solidification front is achieved. (orig.)

Four-branched compounds coupled Si and iron-rich intermetallics in near eutectic Al-Si alloys

International Nuclear Information System (INIS)

Wu, Yuying; Liu, Xiangfa; Jiang, Binggang; Bian, Xiufang

2007-01-01

Many four-branched compounds coupled Si and iron-rich intermetallics were observed in near eutectic Al-Si alloy modified with Al-P master alloy. Such four-branched compounds have never been reported before, but in our case it seems to be commonly observed. In this work the growth characterization of the four-branched compounds are scrutinized with a JXA-8800 electron microprobe (EPMA). More deep study of the formation of four-branched compounds is performed by SEM and TEM analysis. The characterization of the four-branched compounds is that of a primary silicon in the center with four iron-rich intermetallics around. Experimental results also show that the precipitation of primary silicon is the key factor for the formation of four-branched compounds. And WHS-theory explains the growth mechanism of the four-branched compounds. In detail, subsequent twinning within the primary silicon provides four-fold coordination sites on the surface, and then the α-Al(Fe,Mn)-Si phase nucleates on the surface of the primary silicon

The Generation of AlmFe in Dilute Aluminium Alloys with Different Grain Refining Additions

Science.gov (United States)

Meredith, M. W.; Greer, A. L.; Evans, P. V.; Hamerton, R. G.

Al13Fe4, Al6Fe and AlmFe are common intermetallics in commercial AA1XXX series Al alloys. Grain-refining additions (based on either Al-Ti-B or Al-Ti-C) are usually added to such alloys during solidification processing to aid the grain structure development. They also influence the favoured intermetallic and, hence, can affect the materials' properties. This work simulates commercial casting practices in an attempt to determine the mechanisms by which one intermetallic phase is favoured over another by the introduction of grain-refining additions. Directional solidification experiments on Al-0.3wt.%Fe-0.15wt.%Si with and without grain refiner are conducted using Bridgman apparatus. The type, amount and effectiveness of the grain-refining additions are altered and the resulting intermetallic phase selection followed. The materials are characterised using optical microscopy, scanning electron microscopy and X-ray diffraction. AlmFe is seen to form when Al-Ti-B grain-refiner is introduced but only when the refinement is successful; reducing the effectiveness of the refiner led to Al6Fe forming under all conditions. Al-Ti-C refiners are seen to promote AlmFe at lower solidification velocities than when Al-Ti-B was used even though the grain structure was not as refined. These trends can be explained within existing eutectic theory, by considering growth undercooling.

Hot Corrosion Behavior of Ti-48Al and Ti-48Al-2Cr Intermetallic Alloys Produced by Electric Current Activated Sintering

Science.gov (United States)

Garip, Y.; Ozdemir, O.

2018-06-01

In this study, Ti-48Al and Ti-48Al-2Cr (at. pct) intermetallic alloys were produced by electric current activated sintering (ECAS). In order to characterize the phase formation and microstructures of these alloys, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis were used. The XRD result shows that the intermetallic alloys are composed of γ-TiAl and α 2-Ti3Al phases. The microstructure is dense with a low amount of porosity. The hot corrosion behavior of intermetallic alloys was carried out in a salt mixture of 25 wt pct K2SO4 and 75 wt pct Na2SO4 at 700 °C for 180 hours. The morphology of corroded surfaces was observed by SEM-EDS and XRD. Corrosion phases were identified as TiO2 and Al2O3. Well-adhering oxide scale was detected on the corroded sample surface at the end of 180 hours, and no spallation was observed. In addition, a parabolic curve was obtained at the weight change rate vs time.

Hot Corrosion Behavior of Ti-48Al and Ti-48Al-2Cr Intermetallic Alloys Produced by Electric Current Activated Sintering

Science.gov (United States)

Garip, Y.; Ozdemir, O.

2018-03-01

In this study, Ti-48Al and Ti-48Al-2Cr (at. pct) intermetallic alloys were produced by electric current activated sintering (ECAS). In order to characterize the phase formation and microstructures of these alloys, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis were used. The XRD result shows that the intermetallic alloys are composed of γ-TiAl and α 2-Ti3Al phases. The microstructure is dense with a low amount of porosity. The hot corrosion behavior of intermetallic alloys was carried out in a salt mixture of 25 wt pct K2SO4 and 75 wt pct Na2SO4 at 700 °C for 180 hours. The morphology of corroded surfaces was observed by SEM-EDS and XRD. Corrosion phases were identified as TiO2 and Al2O3. Well-adhering oxide scale was detected on the corroded sample surface at the end of 180 hours, and no spallation was observed. In addition, a parabolic curve was obtained at the weight change rate vs time.

Microstructure and Mechanical Properties of Al-5Mg-0.8Mn Alloys with Various Contents of Fe and Si Cast under Near-Rapid Cooling

Directory of Open Access Journals (Sweden)

Yulin Liu

2017-10-01

Full Text Available Al-5Mg-0.8Mn alloys (AA5083 with various iron and silicon contents were cast under near-rapid cooling and rolled into sheets. The aim was to study the feasibility of minimizing the deteriorating level of the harmful Fe-rich phases on the mechanical properties through refining the intermetallics by significantly increasing the casting rate. The results showed that the size and density of the intermetallic particles that remained in the hot bands and the cold rolled sheets increased as the contents of iron and silicon in the alloys were increased. However, the increment of the particle sizes was limited due to the significant refinement of the intermetallics formed during casting under near-rapid cooling. The mechanical properties of the alloys reduced as the contents of iron and silicon in the alloys increased. However, the decrement of tensile strengths and ductility was quite small. Therefore, higher contents of iron and silicon could be used in the Al-5Mg-0.8Mn alloy (AA5083 alloy when the material is cast under near-rapid cooling, such as in the continuous strip casting process.

Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

International Nuclear Information System (INIS)

Cao, J.; Song, X.G.; Wu, L.Z.; Qi, J.L.; Feng, J.C.

2012-01-01

The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni 3 (AlTi) layer, a Ni 2 AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi 3 layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al 3 Ni and Al 3 Ni 2 phases. The reaction sequence of the Al/Ni multilayers was Al 3 Ni → Al 3 Ni 2 → AlNi → AlNi 3 and the final products were AlNi and AlNi 3 phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality. - Highlights: ► Diffusion bonding of TiAl to TiC cermet was realized using Al/Ni multilayer. ► The reaction sequence of the Al/Ni multilayers was Al 3 Ni → Al 3 Ni 2 → AlNi → AlNi 3 . ► The interfacial microstructure of the joint was clarified. ► The application of Al/Ni multilayers improved the joining quality.

Effect of microstructure and surface features on wetting angle of a Fe-3.2 wt%C.E. cast iron with water

Science.gov (United States)

Riahi, Samira; Niroumand, Behzad; Dorri Moghadam, Afsaneh; Rohatgi, Pradeep K.

2018-05-01

In the present study, variation in surface wetting behavior of a hypoeutectic cast iron with its microstructural features and surface roughness was investigated. Samples with an identical composition, i.e. Fe-3.2 wt%C.E., and different microstructures (a gray cast iron with A-type flake graphite and a white cast iron) were fabricated by gravity casting of molten cast iron in a chill mold at different cooling rates. A variation of surface roughness was also developed by polishing, a four-stage electroetching and a four-stage mechanical abrading on the samples. Roughness and water contact angles of all surfaces were then measured. The surface roughness factor and the solid fraction in contact with water by the Wenzel and Cassie-Baxter contact models were also calculated and compared with the corresponding measured contact angles to find out which regime was active. Results indicated that the surface microstructure and the type of constituents present at the surface influenced the cast iron surface wettability and that it was possible to change the surface contact angle by modification of the surface microstructure. The mechanically abraded gray cast iron followed the Wenzel-type regime while the electroetched surfaces of gray cast iron exhibited a transition from Wenzel to Cassie-Baxter type regime. In white cast iron, the results indicated Wenzel type behavior in the electroetched samples while for the mechanically abraded samples, none of these two models could predict the wetting behavior. Furthermore, the wetting angles of both gray and white cast irons were measured after 1, 2, 3 and 4 weeks of air exposure. The results showed that the wetting angles of both samples increased to above 90° after one week of air exposure which was likely due to adsorption of low surface energy hydrocarbons on the surfaces.

Microstructure and Wear Behavior of TiC Coating Deposited on Spheroidized Graphite Cast Iron Using Laser Surfacing

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E. R. I. Mahmoud

2014-10-01

Full Text Available Spheroidal graphite cast iron was laser cladded with TiC powder using a YAG fiber laser at powers of 700, 1000, 1500 and 2000 W. The powder was preplaced on the surface of the specimens with 0.5 mm thickness. Sound cladding and fusion zones were observed at 700, 1000 and 1500 W powers. However, at 2000 W, cracking was observed in the fusion zone. At 700 W, a build-up zone consisted of fine TiC dendrites inside a matrix composed of martensite, cementite (Fe3C, and some blocks of retained austenite was observed. In this zone, all graphite nodules were totally melted. In the fusion zone, some undissolved and partially dissolved graphite nodules appeared in a matrix containing bainite, ferrite, martensite and retained austenite. At 1500 W, the fusion zone had more iron carbides and ferrite, and the HAZ consisted of martensitic structure. At 2000 W, the build-up zone was consisted of TiC particles precipitated in a matrix of eutectic carbides, martensite plus an inter-lamellar retained austenite. The hardness of the cladded area was remarkably improved (1330 HV in case of 700 W: 5.5 times of the hardness of substrate

Synthesis of Ti3AlC2 by spark plasma sintering of mechanically milled 3Ti/xAl/2C powder mixtures

International Nuclear Information System (INIS)

Yang Chen; Jin Songzhe; Liang Baoyan; Liu Guojun; Duan Lianfeng; Jia Shusheng

2009-01-01

Elemental powders of Ti, Al and C were mechanically milled as starting materials for the fabrication of ternary carbide Ti 3 AlC 2 by spark plasma sintering (SPS) technique. The effect of Al content in the starting materials on the Ti 3 AlC 2 synthesis was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to determine the phase identification and observe the microstructure of the synthesized samples. With increasing proper Al content, it was found that the purity of Ti 3 AlC 2 increased and the sintering temperature reduced. The dense and high-purity Ti 3 AlC 2 could be successfully fabricated from 3Ti/1.2Al/2C powders at a lower sintering temperature of 1050 deg. C, holding for 10 min. In addition, the reaction path for the formation of Ti 3 AlC 2 in the present study was proposed

Study of thermodynamic properties of binary and ternary liquid alloys of aluminium with the elements iron, cobalt, nickel and oxygen; Etude des proprietes thermodynamiques des alliages liquides binaires et ternaires de l'aluminium avec les elements fer, cobalt, nickel et l'oxygene

Energy Technology Data Exchange (ETDEWEB)

Vachet, F [CEA Vallee du Rhone, 26-Pierrelatte (France)

1966-07-01

The present work deals with the thermodynamic study of aluminium liquid alloys with the metals iron, cobalt and nickel. The experiments carried out lead to the activity, at 1600 deg C, of aluminium in the (Al, Fe), (Al, Co), (Al, Ni) liquid alloys. The experimental method used consists in studying the partition of aluminium between the liquid immiscible phases made up with the pairs of metals (Fe, Ag), (Co, Ag), (Ni, Ag). The informations so obtained are used for drawing the isothermal equilibrium phases diagrams sections of (Al, Fe, Ag), (Al, Co, Ag), (Al, Ni, Ag) systems. The study of the partition of silver between lead and aluminium joined with the determinations of several authors allows us to determine the aluminium activity, analytically presented, in the metal M (iron cobalt and nickel). The Wagner's interaction parameters of aluminium in metal M are determined. The results obtained as the equilibrium phases diagrams of (Al, M) systems allow to compare the thermodynamic properties of the Al Fe system in liquid and solid states and to estimate the enthalpies of melting of the AlCo and AlNi intermetallic compounds. The activity, at 1600 deg C, of aluminium in (Al, Fe, Co), (Al, Fe, Ni), (Al, Co, Ni) liquid alloys is estimated through thermodynamic properties of binary components systems by application of several methods leading to results in good agreement. The study of aluminium-oxygen interactions in the liquid metallic solvants M allows us to propose an explanation for the shape of the deoxidation equilibrium line of iron, cobalt and nickel by aluminium and to compare the de-oxidizing power of aluminium toward iron, cobalt and nickel oxides. (author) [French] Le travail presente se rapporte a l'etude thermodynamique des alliages liquides de l'aluminium avec les metaux fer, cobalt et nickel. Les experiences effectuees ont pour but de determiner l'activite, a 1600 C, de l'aluminium dans les alliages liquides (Al, Fe), (Al, Co), (Al, Ni). La methode

Grain Refinement of Al-Si-Fe-Cu-Zn-Mn Based Alloy by Al-Ti-B Alloy and Its Effect on Mechanical Properties.

Science.gov (United States)

Yoo, Hyo-Sang; Kim, Yong-Ho; Jung, Chang-Gi; Lee, Sang-Chan; Lee, Seong-Hee; Son, Hyeon-Taek

2018-03-01

We investigated the effects of Al-5.0wt%Ti-1.0wt%B addition on the microstructure and mechanical properties of the as-extruded Al-0.15wt%Si-0.2wt%Fe-0.3wt%Cu-0.15wt%Zn-0.9wt%Mn based alloys. The Aluminum alloy melt was held at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 38:1. AlTiB addition to Al-0.15Si-0.2Fe-0.3Cu-0.15Zn-0.9Mn based alloys resulted in the formation of Al3Ti and TiB2 intermetallic compounds and grain refinement. With increasing of addition AlTiB, ultimate tensile strength increased from 93.38 to 99.02 to 100.01 MPa. The tensile strength of the as-extruded alloys was improved due to the formation of intermetallic compounds and grain refinement.

Model of the Alphinising Coating Crystallisation on Iron Alloys

Directory of Open Access Journals (Sweden)

S. Pietrowski

2007-07-01

Full Text Available The study presents a hypothetical model of crystallisation of the alphinising coating produced on iron alloys by immersion in the bath of silumin. Basing on a wide-range of experiments and investigations, the effect of the type of inserted material (“armco” iron, C45 steel, grey cast iron and nodular graphite cast iron and of the technological regime of the alphinising process (chemical composition of silumin bath, its temperature, the time of holding an insert in the bath, and the insert surface roughness height “Rz” on the coating structure was determined. The type of the coating structure was established by metallographic examinations carried out by optical microscopy, electron transmission microsopy and scanning electron microscopy, using additionally an X-ray microanalyser and X-ray diffraction patterns. The results of these investigations were described in [1÷7]. Basing on the obtained results, a probable model of the crystallisation of an alphi-nising coating on iron alloys, produced by immersion in the alphinising bath, was developed. It has been stated that, most probably, the alphinising process begins when the insert reaches its contact temperature “ts”.. Since that moment, due to the wetting process and convec-tion movement of bath around the insert surface, an intense process of the dissolution starts. A reactive diffusion of the atoms of Fe and Si from the insert to the bath and of the atoms of Al and Si from the bath to the insert takes place. An intermetallic Al3Fe phase is crystallis-ing on the steel, while on the cast iron, a silicon carbide Fe4CSi is growing, probably due to carbon diffusion from graphite. Then, on the steel, as an effect of the peritectic reaction, are successively crystallising the phases of Al12Fe3Si2 and Al9Fe3Si2. The Al3Fe phase probably crystallises on the cast iron to be transformed later, due to peritectic reaction, into an Al12Fe3Si2 phase on which the Al9Fe3Si2 phase will be growing

A Review on the Properties of Iron Aluminide Intermetallics

Directory of Open Access Journals (Sweden)

Mohammad Zamanzade

2016-01-01

Full Text Available Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore, iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications, such as brake disks for windmills and trucks, filtration systems in refineries and fossil power plants, transfer rolls for hot-rolled steel strips, and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i alloy composition; (ii microstructure; and (iii number (type of defects on the thermo-mechanical properties. Additionally, environmental degradation of the alloys, consisting of hydrogen embrittlement, anodic or cathodic dissolution, localized corrosion and oxidation resistance, in different environments should be well known. Recently, some progress in the development of new micro- and nano-mechanical testing methods in addition to the fabrication techniques of micro- and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements, environmental items and crystal structure on the deformation behavior of alloys. In this paper, we will review the extensive work which has been done during the last decades to address each of the points mentioned above.

Effects of Additives on the Corrosion Resistance of Iron Aluminides(Fe-38at.%AI-5at.%Cr)

International Nuclear Information System (INIS)

Choi, H. C.; Kim, C. W.; Joo, S. M.; Choi, D. C.; Kim, K. H.

2001-01-01

The effects of additives on the corrosion resistance of iron aluminides(Fe-38at.%AI-5at.%Cr) were investigated using potentiostat. The specimens were cast by vacuum arc melting. The subsequent homogenization was carried out in Ar gas atmosphere at 1000 .deg. C for 7 days. The corroded surfaces of the tested specimens were observed using an optical microscope and a scanning electron microscope(SEM) after electrochemical tests were carried out in various solutions. While the Hf addition to Fe-38at.%AI-5at.%Cr resulted in equiaxial microstructure, the Zr addition resulted in dendritic microstructure. However, no change in microstructure was observed when Mo was added. The addition of Mo to Fe-38at.%AI-5at.%Cr intermetallic compound was found to increase the pitting potential, which improved the resistance against the pitting corrosion attack. The addition of Hf and Zr resulted in a higher activation current density and a lower pitting potential. These results may indicate that the dendrite structure played a major role in decreasing the pitting corrosion resistance of Fe-38at.%AI-5at%Cr intermetallic compound. The Mo addition to Fe-38at.%AI-5at.%Cr decreased the number and size of pits. In the case of Zr addition, the pits nucleated and grew remarkably at dendritic branches

Microstructure and wear behavior of γ/Al4C3/TiC/CaF2 composite coating on γ-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

International Nuclear Information System (INIS)

Liu Xiubo; Shi Shihong; Guo Jian; Fu Geyan; Wang Mingdi

2009-01-01

As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF 2 in the preparation of precursor NiCr-Cr 3 C 2 -CaF 2 mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al 4 C 3 carbides reinforcement as well as fine isolated spherical CaF 2 solid lubrication particles uniformly dispersed in the NiCrAlTi (γ) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF 2 and the increasing of it's wettability with the NiCrAlTi (γ) matrix during the laser cladding process

Thermal stability of Ni/Ti/Al ohmic contacts to p-type 4H-SiC

Energy Technology Data Exchange (ETDEWEB)

Yu, Hailong; Shen, Huajun, E-mail: shenhuajun@ime.ac.cn; Tang, Yidan; Bai, Yun; Liu, Xinyu [Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); Zhang, Xufang [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wu, Yudong; Liu, Kean [Zhuzhou CSR Times Electric Co., Ltd, ZhuZhou 412001 (China)

2015-01-14

Low resistivity Ni/Ti/Al ohmic contacts on p-type 4H-SiC epilayer were developed, and their thermal stabilities were also experimentally investigated through high temperature storage at 600 °C for 100 h. The contact resistance of the Al/Ti/Ni/SiC contacts degraded in different degrees, and the contact morphology deteriorated with the increases of the average surface roughness and interface voids. X-ray spectra showed that Ni{sub 2}Si and Ti{sub 3}SiC{sub 2}, which were formed during ohmic contact annealing and contributed to low contact resistivity, were stable under high temperature storage. The existence of the TiAl{sub 3} and NiAl{sub 3} intermetallic phases was helpful to prevent Al agglomeration on the interface and make the contacts thermally stable. Auger electron spectroscopy indicated that the incorporation of oxygen at the surface and interface led to the oxidation of Al or Ti resulting in increased contact resistance. Also, the formation of these oxides roughened the surface and interface. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism dominates the current transport for contacts before and after the thermal treatment. It suggests that the Ni/Ti/Al composite ohmic contacts are promising for SiC devices to be used in high temperature applications.

Theoretical analysis of compatibility of several reinforcement materials with NiAl and FeAl matrices

Science.gov (United States)

Misra, Ajay K.

1989-01-01

Several potential reinforcement materials were assessed for their chemical, coefficient of thermal expansion (CTE), and mechanical compatibility with the intermetallic matrices based on NiAl and FeAl. Among the ceramic reinforcement materials, Al2O3, TiC, and TiB2, appear to be the optimum choices for NiAl and FeAl matrices. However, the problem of CTE mismatch with the matrix needs to be solved for these three reinforcement materials. Beryllium-rich intermetallic compounds can be considered as potential reinforcement materials provided suitable reaction barrier coatings can be developed for these. Based on preliminary thermodynamic calculations, Sc2O3 and TiC appear to be suitable as reaction barrier coatings for the beryllides. Several reaction barrier coatings are also suggested for the currently available SiC fibers.

The machinability of cast titanium and Ti-6Al-4V.

Science.gov (United States)

Ohkubo, C; Watanabe, I; Ford, J P; Nakajima, H; Hosoi, T; Okabe, T

2000-02-01

This study investigated the machinability (ease of metal removal) of commercially pure (CP) titanium and Ti-6Al-4V alloy. Both CP Ti and Ti-6Al-4V were cast into magnesia molds. Two types of specimens (with alpha-case and without alpha-case) were made for CP Ti and Ti-6Al-4V. Machinability (n = 5) was evaluated as volume loss (mm3) by cutting/grinding the 3.0 mm surface using fissure burs and silicon carbide (SiC) under two machining conditions: (1) two machining forces (100 or 300 gf) at two rotational speeds (15000 or 30000 rpm) for 1 min, and (2) constant machining force of 100 gf and rotational speed of 15000 rpm for 1, 2, 5, 10, and 30 min. As controls, conventionally cast Co-Cr and Type IV gold alloys were evaluated in the same manner as the titanium. When fissure burs were used, there was a significant difference in the machinability between CP titanium with alpha-case and without alpha-case. On the other hand, there was no appreciable difference in the amount of metal removed for each tested metal when using the SiC points.

Tailoring ultrafine grained and dispersion-strengthened Ti 2 AlC/TiAl ...

Indian Academy of Sciences (India)

In situ Ti 2 AlC/TiAl composite was fabricated by hot-pressing method via the reaction system of Ti 3 AlC 2 and Ti-Al pre-alloyed powders at low temperature of 1150 ∘ C. The composite mainly consisted of TiAl, Ti 3 Al and Ti 2 AlC phases. Fine Ti 2 AlC particles were homogeneously distributed and dispersed in the matrix.

Iron aluminide useful as electrical resistance heating elements

Science.gov (United States)

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

1997-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

Energy Technology Data Exchange (ETDEWEB)

Cao, J., E-mail: cao_jian@hit.edu.cn [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China); Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150001 (China); Song, X.G. [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China); Wu, L.Z. [Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150001 (China); Qi, J.L.; Feng, J.C. [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China)

2012-02-29

The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni{sub 3}(AlTi) layer, a Ni{sub 2}AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi{sub 3} layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al{sub 3}Ni and Al{sub 3}Ni{sub 2} phases. The reaction sequence of the Al/Ni multilayers was Al{sub 3}Ni {yields} Al{sub 3}Ni{sub 2} {yields} AlNi {yields} AlNi{sub 3} and the final products were AlNi and AlNi{sub 3} phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality. - Highlights: Black-Right-Pointing-Pointer Diffusion bonding of TiAl to TiC cermet was realized using Al/Ni multilayer. Black-Right-Pointing-Pointer The reaction sequence of the Al/Ni multilayers was Al{sub 3}Ni {yields} Al{sub 3}Ni{sub 2} {yields} AlNi {yields} AlNi{sub 3}. Black-Right-Pointing-Pointer The interfacial microstructure of the joint was clarified. Black-Right-Pointing-Pointer The application of Al/Ni multilayers improved the joining quality.

Fatigue properties of Fe-Al intermetallic coatings prepared by plasma spraying

Czech Academy of Sciences Publication Activity Database

Mušálek, Radek; Kovářík, O.; Skiba, Tomáš; Haušild, P.; Karlík, M.; Colmenares-Angulo, J.

2010-01-01

Roč. 18, č. 7 (2010), s. 1415-1418 ISSN 0966-9795. [FEAL 2009 - 5th Discussion Meeting on the Development of Innovative Iron Aluminium Alloys. Prague, 21.09.2009-24.09.2009] R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : Iron aluminides * Fatigue resistance and crack growth * plasma spraying * scanning electron microscopy Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.327, year: 2010 http://www.sciencedirect.com/science?_ob=GatewayURL&_method=citationSearch&_uoikey=B6TX8-4YGHK94-2&_origin=SDEMFRHTML&_version=1&md5=557fd571c715e5f2cff573d5255bb184

Sintering of (Ni,Mg)(Al,Fe)2O4 Materials and their Corrosion Process in Na3AlF6-AlF3-K3AlF6 Electrolyte

Science.gov (United States)

Xu, Yibiao; Li, Yawei; Yang, Jianhong; Sang, Shaobai; Wang, Qinghu

2017-06-01

The application of ledge-free sidewalls in the Hall-Héroult cells can potentially reduce the energy requirement of aluminum production by about 30 pct (Nightingale et al. in J Eur Ceram, 33:2761-2765, 2013). However, this approach poses great material challenges since such sidewalls are in direct contact with corrosive electrolyte. In the present paper, (Ni,Mg)(Al,Fe)2O4 materials were prepared using fused magnesia, reactive alumina, nickel oxide, and iron oxide powders as the starting materials. The sintering behaviors of specimens as well as their corrosion resistance to molten electrolyte have been investigated by means of X-ray diffraction and scanning electron microscope. The results show that after firing at temperature ranging from 1673 K (1400 °C) up to 1873 K (1600 °C), all the specimens prepared are composed of single-phase (Ni,Mg)(Al,Fe)2O4 composite spinel, the lattice parameter of which increases with increasing Fe3+ ion concentration. Increasing the iron oxide content enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed smaller pores in the matrix. The corrosion tests show that corrosion layers consist of fluoride and Ni(Al,Fe)2O4 composite spinel grains are produced in specimens with Fe/Al mole ratio no more than 1, whereas dense Ni(Al,Fe)2O4 composite spinel layers are formed on the surface of the specimens with Fe/Al mole ratio more than 1. The dense Ni(Al,Fe)2O4 composite spinel layers formed improve the corrosion resistance of the specimens by inhibiting the infiltration of electrolyte and hindering the chemical reaction between the specimen and electrolyte.

Evaluation of the intrinsic and extrinsic fracture behavior of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Cooper, B.R.; Kang, B.S. [West Virginia Univ., Morgantown, WV (United States)

1998-07-27

Iron aluminides have excellent corrosion resistance in high-temperature oxidizing-sulfidizing environments; however, there are problems at room and medium temperatures with hydrogen embrittlement as related to exposure to moisture. In this research, a coordinated computational modeling/experimental study of mechanisms related to environmental-assisted fracture behavior of selected iron aluminides has been undertaken. The modeling and the experimental work connect at the level of coordinated understanding of the mechanisms for hydrogen penetration and for loss of strength and susceptibility to fracture. The focus of the modeling component has been on the challenging question of accurately predicting the iron vacancy formation energy in Fe{sub 3}Al and the subsequent tendency, if present, for vacancy clustering. The authors have successfully performed, on an ab initio basis, the first calculation of the vacancy formation energy in Fe{sub 3}Al. These calculations include lattice relaxation effects which are quite large for one of the two types of iron sites. This has significant implications for vacancy clustering effects with consequences for hydrogen diffusion. Indeed, the ab-initio-based estimate of the divacancy binding energy indicates a likely tendency toward such clustering for iron vacancies on the sites with large lattice relaxation. The experimental work has focused on the relationship of the choice and concentration of additives to the improvement of resistance to hydrogen embrittlement and hence to the fracture behavior.

Structural and magnetic order of ThMn12-type rare earth-iron-aluminium intermetallics studied by neutron diffraction

International Nuclear Information System (INIS)

Schaefer, W.; Halevy, I.; Gal, J.

2000-01-01

neutron powder diffraction data of ThMn 12 -type compounds RFe 4 Al 8 , RFe 5 Al 7 , and RFe 6 Al 6 (R = heavy rare earth) are compared to work out the structural variations and the different magnetic properties of these ternary intermetallics as a function of increasing iron concentrations. The variations of unit cell metric, of atomic coordinations and of interatomic distances are discussed. A magnetic phase diagram is presented showing the increase of the magnetic ordering temperatures from 120 K to 340 K and the change of the magnetic order from two separate magnetic phase transitions of rare earth and iron sublattices to one common ferrimagnetic transition of both sublattices, when changing the ratio of Fe/Al atoms from 4/8 to 6/6, respectively. Long range order is hampered by frozen spins. Magnetically ordered rare earth and iron moments are given. (orig.)

Preparation of Ti3Al intermetallic compound by spark plasma sintering

Science.gov (United States)

Ito, Tsutomu; Fukui, Takahiro

2018-04-01

Sintered compacts of single phase Ti3Al intermetallic compound, which have excellent potential as refractory materials, were prepared by spark plasma sintering (SPS). A raw powder of Ti3Al intermetallic compound with an average powder diameter of 176 ± 56 μm was used in this study; this large powder diameter is disadvantageous for sintering because of the small surface area. The samples were prepared at sintering temperatures (Ts) of 1088, 1203, and 1323 K, sintering stresses (σs) of 16, 32, and 48 MPa, and a sintering time (ts) of 10 min. The calculated relative densities based on the apparent density of Ti3Al provided by the supplier were approximately 100% under all sintering conditions. From the experimental results, it was evident that SPS is an effective technique for dense sintering of Ti3Al intermetallic compounds in a short time interval. In this report, the sintering characteristics of Ti3Al intermetallic compacts are briefly discussed and compared with those of pure titanium compacts.

Refining of cast intermetallic alloy Ti - 43 % Al - X (Nb, Mo, B) microstructure using heat treatment

International Nuclear Information System (INIS)

Imaev, R.M.; Imaev, V.M.; Khismatullin, T.G.

2006-01-01

The microstructure and high temperature mechanical properties are studied in a cast alloy Ti - 43 % Al - X (Nb, Mo, B) using methods of optical and scanning electron microscopy, X ray spectrum microanalysis and differential thermal analysis. The alloy belongs to a new class of β-solidifying γ-TiAl+α 2 -Ti 3 Al alloys. The alloy is investigated as cast and after heat treatment that promotes grain refinement. Mechanical properties are determined on tensile tests at 1000 and 1100 deg C in the air [ru

Effects of alloying elements (Mn, Co, Al, W, Sn, B, C and S) on biodegradability and in vitro biocompatibility of pure iron.

Science.gov (United States)

Liu, B; Zheng, Y F

2011-03-01

Pure iron was determined to be a valid candidate material for biodegradable metallic stents in recent animal tests; however, a much faster degradation rate in physiological environments was desired. C, Mn, Si, P, S, B, Cr, Ni, Pb, Mo, Al, Ti, Cu, Co, V and W are common alloying elements in industrial steels, with Cr, Ni, Mo, Cu, Ti, V and Si being acknowledged as beneficial in enhancing the corrosion resistance of iron. The purpose of the present work (using Fe-X binary alloy models) is to explore the effect of the remaining alloying elements (Mn, Co, Al, W, B, C and S) and one detrimental impurity element Sn on the biodegradability and biocompatibility of pure iron by scanning electron microscopy, X-ray diffraction, metallographic observation, tensile testing, microhardness testing, electrochemical testing, static (for 6 months) and dynamic (for 1 month with various dissolved oxygen concentrations) immersion testing, cytotoxicity testing, hemolysis and platelet adhesion testing. The results showed that the addition of all alloying elements except for Sn improved the mechanical properties of iron after rolling. Localized corrosion of Fe-X binary alloys was observed in both static and dynamic immersion tests. Except for the Fe-Mn alloy, which showed a significant decrease in corrosion rate, the other Fe-X binary alloy corrosion rates were close to that of pure iron. It was found that compared with pure iron all Fe-X binary alloys decreased the viability of the L929 cell line, none of experimental alloying elements significantly reduced the viability of vascular smooth muscle cells and all the elements except for Mn increased the viability of the ECV304 cell line. The hemolysis percentage of all Fe-X binary alloy models were less than 5%, and no sign of thrombogenicity was observed. In vitro corrosion and the biological behavior of these Fe-X binary alloys are discussed and a corresponding mechanism of corrosion of Fe-X binary alloys in Hank's solution proposed. As a

Recent advances in ordered intermetallics

International Nuclear Information System (INIS)

Liu, C.T.

1995-01-01

Ordered intermetallic alloys based on aluminides and silicides offer many advantages for structural use at elevated temperatures in hostile environments. Their attractive properties include excellent oxidation and corrosion resistance, light weight, and superior strength at elevated temperatures. The major concern for structural use of intermetallics was their low ductility and poor fracture resistance at ambient temperatures. For the past ten years, considerable effort has been devoted to the research and development of ordered intermetallic alloys, and good progress has been made on understanding intrinsic and extrinsic factors controlling brittle fracture in intermetallic alloys based on aluminides and silicides. Parallel efforts on alloy design have led to the development of a number of ductile and strong intermetallic alloys based on Ni(3)Al, NiAl, Fe(3)Al, FeAl, Ti(3)Al and TiAl systems for structural applications. (orig.)

Design and syntheses of hybrid metal-organic materials based on K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] metallotectons

Science.gov (United States)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao; Wang, Wenqiang; Wang, Lei

2016-05-01

By using K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] (C2O42-=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C2O4)2(H2O)2}2]·(H-L1)2·H2O 1, [Fe(C2O4)Cl2]·(H2-L2)0.5·(L2)0.5·H2O 2, [{Fe(C2O4)1.5Cl2}2]·(H-L3)43, [Fe2(C2O4)Cl8]·(H2-L4)2·2H2O 4, K[Al(C2O4)3]·(H2-L5)·2H2O 5, K[Al(C2O4)3]·(H-L6)2·2H2O 6, K[Cr(C2O4)3]·2H2O 7, Na[Fe(C2O4)3]·(H-L6)2·2H2O 8 (with L1=4-dimethylaminopyridine, L2=2,3,5,6-tetramethylpyrazine, L3=2-aminobenzimidazole, L4=1,4-bis-(1H-imidazol-1-yl)benzene, L5=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L6=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C2O4)2(H2O)2]- unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C2O4)Cl2]- anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe2(C2O4)3Cl4]4- unit. Compound 4 features distinct [Fe2(C2O4)Cl8]4- units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C2O4)3]3- units and K+ cations. The 1D chains are further extended into 3D antionic H-bonded framework through O-H···O H-bonds. Compounds 6-8 show 2D [KAl(C2O4)3]2- layer, [KCr(C2O4)3]2- layer and [NaFe(C2O4)3]2- layer, respectively.

MAX phase formation by intercalation upon annealing of TiC{sub x}/Al (0.4 {<=} x {<=} 1) bilayer thin films

Energy Technology Data Exchange (ETDEWEB)

Abdulkadhim, Ahmed; Takahashi, Tetsuya [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany); Music, Denis, E-mail: music@mch.rwth-aachen.de [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany); Munnik, Frans [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden (Germany); Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany)

2011-09-15

TiC{sub x}/Al bilayer thin films were synthesized using combinatorial magnetron sputtering to study the influence of C content on the reaction products at different annealing temperatures. Based on energy-dispersive X-ray analysis calibrated by elastic recoil detection analysis data, x in TiC{sub x} was varied from 0.4 to 1.0. Film constitution was studied by X-ray diffraction before and after annealing at temperatures from 500 to 1000 deg. C. The formation of TiC{sub x} and Al in the as-deposited samples over the whole C/Ti range was identified. Upon annealing, TiC{sub x} reacts with Al to form Ti-Al-based intermetallics. At temperatures as low as 700 deg. C, the formation of MAX phases (space group P6{sub 3}/mmc) is observed at x {<=} 0.7. Based on the comparison between the C content induced changes in the lattice spacing of TiC{sub x} and Ti{sub 2}AlC as well as Ti{sub 3}AlC{sub 2}, we infer the direct formation of MAX phases by Al intercalation into TiC{sub x} for x {<=} 0.7.

Microstructure and Properties of Fe3Al-Fe3AlC x Composite Prepared by Reactive Liquid Processing

Science.gov (United States)

Verona, Maria Nalu; Setti, Dalmarino; Paredes, Ramón Sigifredo Cortés

2018-04-01

A Fe3Al-Fe3AlC x composite was prepared using reactive liquid processing (RLP) through controlled mixture of carbon steel and aluminum in the liquid state. The microstructure and phases of the composite were assessed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, optical microscopy, and differential scanning calorimetry. In addition, the density, hardness, microhardness, and elastic modulus were evaluated. The Fe3Al-Fe3AlC x composite consisted of 65 vol pct Fe3Al and 35 vol pct Fe3AlC x ( κ). The κ phase contained 10.62 at. pct C, resulting in the stoichiometry Fe3AlC0.475. The elastic modulus of the Fe3Al-Fe3AlC0.475 composite followed the rule of mixtures. The RLP technique was shown to be capable of producing Fe3Al-Fe3AlC0.475 with a microstructure and properties similar to those achieved using other processing techniques reported in the literature.

Boron solubility in Fe-Cr-B cast irons

International Nuclear Information System (INIS)

Guo Changqing; Kelly, P.M.

2003-01-01

Boron solubility in the as-cast and solution treated martensite of Fe-Cr-B cast irons, containing approximately 1.35 wt.% of boron, 12 wt.% of chromium, as well as other alloying elements, has been investigated using conventional microanalysis. The significant microstructural variations after tempering at 750 deg. C for 0.5-4 h, compared with the original as-cast and solution treated microstructures, indicated that the matrix consisted of boron and carbon supersaturated solid solutions. The boron solubility detected by electron microprobe was between 0.185-0.515 wt.% for the as-cast martensite and 0.015-0.0589 wt.% for the solution treated martensite, much higher than the accepted value of 0.005 wt.% in pure iron. These remarkable increases are thought to be associated with some metallic alloying element addition, such as chromium, vanadium and molybdenum, which have atomic diameters larger than iron, and expand the iron lattice to sufficiently allow boron atoms to occupy the interstitial sites in iron lattice

Effect of Heat Treatment on Morphology of Fe-Rich Intermetallics in Hypereutectic Al-Si-Cu-Ni Alloy with 1.26 pct Fe

Science.gov (United States)

Sha, Meng; Wu, Shusen; Wan, Li; Lü, Shulin

2013-12-01

Cobalt is generally considered as the element that can neutralize the negative effects of iron in Al alloys, such as inducing fracture and failure for stress concentration. Nevertheless, Fe-rich intermetallics would be inclined to form coarse plate-like δ-Al4(Fe, Co, Ni)Si2 particles when the content of Fe was high, which could also cause inferior mechanical properties. The dissolution and transformation of δ-Al4(Fe, Co, Ni)Si2 phase in solution heat-treated samples of Al-20Si-1.85Cu-1.05Ni-1.26Fe-1.35Co alloy were studied using optical microscopy, image analysis, and scanning electron microscopy. The effects of solution heat treatment time ranging from 0 to 9 hours at 783.15 K (510 °C) on mechanical properties were also investigated. The coarse plate-like δ-Al4(Fe, Co, Ni)Si2 particles varied slowly through concurrent dissolution along widths and at the plate tips as solution treatment time increased, which could be explained from diffusion-induced grain boundary migration. Solution heat treatment also has an important influence on mechanical properties. The maximum ultimate tensile strength and yield strength after T6 treatment were 258 and 132 MPa, respectively, while the maximum hardness was 131 HB. Compared with those of the samples in the as-cast state, they increased by 53, 42, and 28 pct, respectively. Moreover, δ-Al4(Fe, Co, Ni)Si2 phase, which appears as a coarse plate-like particle in two dimensions, is actually a cuboid in three dimensions. The length of this cuboid is close to the width, while the height is much smaller.

Effect of the AlCr20 Addition on the Microstructure of Secondary AlSi7Mg0.3 Alloy

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2014-06-01

Full Text Available This paper deals with influence of chrome addition and heat treatment on segregation of iron based phases in the secondary alloy AlSi7Mg0.3 microstructure by chrome and heat treatment. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type or by heat treatment. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases.

Effect of impurities on microstructure and structural propertiesof the as-cast and treated Al-Zn alloys

Directory of Open Access Journals (Sweden)

Douniazed Lamrous

2014-03-01

Full Text Available The microstructure of two Al-Zn alloys (with 10 and 30 wt.%Zn content produced by melting in the high frequency induction furnace were investigated by means of scanning electron microscopy (SEM, energy dispersive X-ray (EDX spectroscopy, X-ray diffraction (XRD analysis and the microhardness tests. The results indicate that the presence of iron impurity causes the formation of eutectic (Al,Zn3Fe in both alloys. The presence of the silicon impurity results in the formation of the phase separation in the Al-10%Zn as-cast alloy. The columnar to equiaxed transition was produced only in the Al-30%Zn as-cast alloy. The Vickers microhardness is higher in the equiaxed zone than in the columnar to equiaxed transition (CET zone. The presence of iron causes intermetallic phase formation (Al, Fe, Si3,6Zn in the Al-30%Zn as-cast alloy enabling an increase in the lattice parameter. After a homogenization treatment, the microstructure of Al-Zn treated alloys consists only of α dendrites and stable eutectic phase.

Wear Behavior of Cold Pressed and Sintered Al2O3/TiC/CaF2Al2O3/TiC Laminated Ceramic Composite

Institute of Scientific and Technical Information of China (English)

Xuefeng YANG; Jian CHENG; Peilong SONG; Shouren WANG; Liying YANG; Yanjun WANG; Ken MAO

2013-01-01

A novel laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance,such as low friction coefficient and low wear rate.Al2O3/TiC/CaF2 and Al2O3/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure.Solid lubricant CaF2 was added evenly into the Al2O3/TiC/CaF2 layer to reduce the friction and wear.Al2O3/TiC ceramic was also cold pressed and sintered for comparison.Friction analysis of the two ceramics was then conducted via a wear-and-tear machine.Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum,respectively.Results showed that the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al2O3/TiC ceramic alone because of the addition of CaF2 into the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite.Under the friction load,the tiny CaF2 particles were scraped from the Al2O3/TiC/CaF2 layer and spread on friction pairs before falling off into micropits.This process formed a smooth,self-lubricating film,which led to better anti-wear properties.Adhesive wear is the main wear mechanism of Al2O3/TiC/CaF2 layer and abrasive wear is the main wear mechanism of Al2O3/TiC layer.

Interface reactions in the Al-Si-SiC and Mg-Al-Al{sub 2}O{sub 3} composite systems

Energy Technology Data Exchange (ETDEWEB)

Johnson, P.K. [Commission of the European Communities, Petten (Netherlands). Inst. for Advanced Materials; Fazal-Ur-Rehman [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; Fox, S. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; Flower, H.M. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; West, D.R.F.

1995-12-31

Structural and compositional observations are reported on the influence of the interfaces on the mechanisms and kinetics of liquid metal-ceramic reactions in Al-SiC, Al-Si-SiC, Mg-Al{sub 2}O{sub 3} and Mg-Al-Al{sub 2}O{sub 3} composites. The aluminium based materials contained up to 20 vol% SiC in particulate form, and were produced by a spray casting process; subsequently the interface reactions were studied in samples heated to temperatures up to 1100 C. The reaction product was Al{sub 4}C{sub 3} in both Al-SiC and Al-Si-SiC composites. The influence of the crystallography and topology of the SiC particle surfaces on the nucleation of the Al{sub 4}C{sub 3} has been demonstrated; surface asperities play an important role. Growth of nuclei proceeds to form continuous reaction product layers which control the subsequent kinetics. The magnesium based composites contained 5 vol% Al{sub 2}O{sub 3} fibres (3 {mu}m in diameter), and were produced by a liquid infiltration process. SD Safimax fibres with relatively low and high porosity, and also RF Saffil fibres, with a silica binder, were investigated. Fibre porosity plays a major role in accelerating the penetration of Mg into the fibres with reaction to form MgO. Silica binder on the fibre surface transforms to MgO. The reaction rate was reduced by the presence of aluminium in the matrix. The factors controlling the reactions in the aluminium and magnesium based composites are compared. (orig.)

Mechanochemically synthesized Al2O3-TiC nanocomposite

International Nuclear Information System (INIS)

Mohammad Sharifi, E.; Karimzadeh, F.; Enayati, M.H.

2010-01-01

Al 2 O 3 -TiC nanocomposite was synthesized by ball milling of aluminum, titanium oxide and graphite powder mixtures. Effect of the milling time and heat treatment temperatures were investigated. The structural evolution of powder particles after different milling times was studied by X-ray diffractometry and scanning electron microscopy. The results showed that after 40 h of ball milling the Al/TiO 2 /C reacted with a self-propagating combustion mode producing Al 2 O 3 -TiC nanocomposite. In final stage of milling, alumina and titanium carbide crystallite sizes were less than 10 nm. After annealing at 900 o C for 1 h, Al 2 O 3 and TiC crystallite sizes remained constant, however increasing annealing temperature to 1200 o C increased Al 2 O 3 and TiC crystallite size to 65 and 30 nm, respectively. No phase change was observed after annealing of the synthesized Al 2 O 3 -TiC powder.

Microstructure and wear resistance of a laser clad TiC reinforced nickel aluminides matrix composite coating

International Nuclear Information System (INIS)

Chen, Y.; Wang, H.M.

2004-01-01

Wear resistant TiC/(NiAl-Ni 3 Al) composite coating was fabricated on a substrate of electrolyzed nickel by laser cladding using Ni-Al-Ti-C alloy powders. The laser clad coating is metallurgically bonded to the substrate and has a homogenous fine microstructure consisting of the flower-like equiaxed TiC dendrite and the dual phase matrix of NiAl and Ni 3 Al. The intermetallic matrix composite coating exhibits excellent wear resistance under both room- and high-temperature sliding wear test conditions due to the high hardness of TiC coupled with the strong atomic bonds of intermetallic matrix

Influence of Nickel Addition on Properties of Secondary AlSi7Mg0.3 Alloy

Directory of Open Access Journals (Sweden)

Richtárech L.

2015-06-01

Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by nickel. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations. Some elements eliminates iron by changing iron intermetallic phase morphology, decreasing its extent and by improving alloy properties. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of nickel as iron corrector of iron based phases.

Electrochemical corrosion behavior and elasticity properties of Ti-6Al-xFe alloys for biomedical applications.

Science.gov (United States)

Lu, Jinwen; Zhao, Yongqing; Niu, Hongzhi; Zhang, Yusheng; Du, Yuzhou; Zhang, Wei; Huo, Wangtu

2016-05-01

The present study is to investigate the microstructural characteristics, electrochemical corrosion behavior and elasticity properties of Ti-6Al-xFe alloys with Fe addition for biomedical application, and Ti-6Al-4V alloy with two-phase (α+β) microstructure is also studied as a comparison. Microstructural characterization reveals that the phase and crystal structure are sensitive to the Fe content. Ti-6Al alloy displays feather-like hexagonal α phase, and Ti-6Al-1Fe exhibits coarse lath structure of hexagonal α phase and a small amount of β phase. Ti-6Al-2Fe and Ti-6Al-4Fe alloys are dominated by elongated, equiaxed α phase and retained β phase, but the size of α phase particle in Ti-6Al-4Fe alloy is much smaller than that in Ti-6Al-2Fe alloy. The corrosion resistance of these alloys is determined in SBF solution at 37 °C. It is found that the alloys spontaneously form a passive oxide film on their surface after immersion for 500 s, and then they are stable for polarizations up to 0 VSCE. In comparison with Ti-6Al and Ti-6Al-4V alloys, Ti-6Al-xFe alloys exhibit better corrosion resistance with lower anodic current densities, larger polarization resistances and higher open-circuit potentials. The passive layers show stable characteristics, and the wide frequency ranges displaying capacitive characteristics occur for high iron contents. Elasticity experiments are performed to evaluate the elasticity property at room temperature. Ti-6Al-4Fe alloy has the lowest Young's modulus (112 GPa) and exhibits the highest strength/modulus ratios as large as 8.6, which is similar to that of c.p. Ti (8.5). These characteristics of Ti-6Al-xFe alloys form the basis of a great potential to be used as biomedical implantation materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Vacuum brazing of TiAl48Cr2Nb2 casting alloys based on TiAl (γ intermetallic compound

Directory of Open Access Journals (Sweden)

Z. Mirski

2010-01-01

Full Text Available A growing interest in modern engineering materials characterised by increasingly better operational parameters combined with a necessity to obtain joints of such materials representing good operation properties create important research and technological problems of today. These issues include also titanium joints or joints of titanium alloys based on intermetallic compounds. Brazing is one of the basic and sometimes even the only available welding method used for joining the aforesaid materials in production of various systems, heat exchangers and, in case of titanium alloys based on intermetallic compounds, turbine elements and space shuttle plating etc. This article presents the basic physical and chemical properties as well as the brazability of alloys based on intermetallic compounds. The work also describes the principle and mechanisms of diffusion-brazed joint formation as well as reveals the results of metallographic and strength tests involving diffusion-welded joints of TiAl48Cr3Nb2 casting alloy based on TiAl (γ phase with the use of sandwich-type layers of silver-based parent metal (grade B- Ag72Cu-780 (AG 401 and copper (grade CF032A. Structural examination was performed by means of light microscopy, scanning electron microscope (SEM and energy dispersion spectrometer (EDS. Furthermore, the article reveals the results of shear strength tests involving the aforementioned joints.

Mictomagnetic, ferromagnetic, and antiferromagnetic transitions in La(FexAl1–x)13 intermetallic compounds

NARCIS (Netherlands)

Palstra, T.T.M.; Nieuwenhuys, G.J.; Mydosh, J.A.; Buschow, K.H.J.

1985-01-01

Cubic La(FexAl1–x)13 intermetallic compounds can be stabilized with iron concentration x between 0.46 and 0.92 in the NaZn13-type structure (D23) with Fm3c (Oh6) space-group symmetry. Here the Fe-Fe coordination number can increase up to 12. At low x values, a mictomagnetic regime occurs with

Aleaciones cuasicristalinas Al93Fe3Cr2Ti2

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García-Escorial, Asunción

2015-12-01

Full Text Available Aluminium alloy powder having a nominal composition of Al93Fe3Cr2Ti2 (at% has been prepared using gas atomisation. The atomised powder present a microstructure of an aluminium matrix reinforced with a spherical quasicrystalline icosahedral phase, in the range of nanometre in size. The powder was consolidated into bars using warm extrusion. The microstructure of the extruded bars retains the quasicrystalline microstructure and the bars present outstanding mechanical properties, i.e. proof stress of 280 MPa at 300 °C. Upon heating the microstructure evolves towards the equilibrium. The thermal evolution was investigated by means of x-ray diffraction, differential scanning calorimeter, scanning electron microscopy and transmission electron microscopy. According to these observations a transformation in two steps is proposed. A first step consists in the decomposition of the supersaturated solid solution of the matrix and the quasicrystals, and a second step in the transformation of the quasicrystals into the equilibrium phases.Se ha obtenido por atomización por gas polvo de la aleación Al93Fe3Cr2Ti2 (at%. Este polvo presenta una microestructura de una matriz de aluminio reforzada por precipitados icosaédricos de tamaño nanométrico. El polvo fue consolidado por extrusión en forma de barras cilíndricas. La microestructura de las barras retiene la microestructura cuasicristalina de las partículas de polvo. El material consolidado presenta propiedades mecánicas prometedoras, como un límite elástico de 280 MPA a 300 °C. Con los tratamientos térmicos, la microestructura evoluciona hacia el equilibrio. Esta evolución se estudia por difracción de rayos x, calorimetría diferencial de barrido, microscopías electrónicas de barrido y de transmisión. A la luz de los resultados obtenidos se propone que la transformación de las fases con el tiempo de tratamiento térmico ocurre en dos pasos. Primeramente, tiene lugar la descomposición de la

Diffusion Coefficient in the Zinc Coating Shaped on the Surface of Cast Iron and Steel Alloys

Directory of Open Access Journals (Sweden)

Kopyciński D.

2015-06-01

Full Text Available The article presents the method to assess the diffusion coefficient D in the sub-layer of intermetallic phases formed during hot-dip galvanizing “Armco” iron and ductile cast iron EN-GJS-500-7. Hot-dip galvanizing is one of the most popular forms of long-term protection of Fe-C alloys against corrosion. The process for producing a protective layer of sufficient quality is closely related to diffusion of atoms of zinc and iron. The simulation consist in performed a hot-dip galvanizing in laboratory condition above Fe-C alloys, in the Department of Engineering of Cast Alloys and Composites. Galvanizing time ranged from 15 to 300 seconds. Then metallographic specimens were prepared, intermetallic layers were measured and diffusion coefficient (D were calculated. It was found that the diffusion coefficient obtained during hot-dip galvanizing “Armco” iron and zinc is about two orders of magnitude less than the coefficient obtained on ductile cast iron EN-GJS-500-7.

Characterization of laser deposited Ti6Al4V/TiC composite powders on a Ti6Al4V substrate

CSIR Research Space (South Africa)

Mahamood, RM

2014-01-01

Full Text Available This paper reports the material characterization of Ti6Al4V/TiC composite produced by laser metal deposition. The Ti6Al4V/TiC composites were deposited with a composition ratio of 50 wt.% Ti64l4V and 50 wt.% TiC. The depositions were achieved...

Effect of ion plating TiN on the oxidation of sputtered NiCrAlY-coated Ti3Al-Nb in air at 850-950 C

International Nuclear Information System (INIS)

Rizzo, F.C.; Zeng, C.; Chinese Academy of Sciences, Shenyang; Wu, W.

1998-01-01

A single sputtered NiCrAlY coating and a complex coating of inner ion-plated TiN and outer sputtered NiCrAlY were prepared on the intermetallic compound Ti 3 Al-Nb. Their oxidation behavior was examined at 850, 900, and 950 C in air by thermal gravimetry combined with XRD, SEM, and EDAX. The results showed that Ti 3 Al-Nb followed approximately parabolic oxidation, forming an outer thin Al 2 O 3 -rich scale and an inner TiO 2 -rich layer doped with Nb at the three temperatures. The TiO 2 -rich layer doped with Nb dominated the oxidation reaction. The single NiCrAlY coating did not follow parabolic oxidation exactly at 850 and 950 C, but oxidized approximately in a parabolic manner, because the instantaneous parabolic constants changed slightly with time. Besides the Al 2 O 3 scale, TiO 2 formed from the coating surface at the coating-substrate interface. The deterioration of the coating accelerated with increasing temperature. The NiCrAlY-TiN coating showed two-stage parabolic oxidation at 850 and 900 C, and an approximate parabolic oxidation at 950 C. The TiN layer was effective as a barrier to inhibit coating-alloy interdiffusion

Strengthening mechanisms in Ti-6Al-4V/TiC composites

International Nuclear Information System (INIS)

Johnson, A.J. Wagoner; Kumar, K.S.; Briant, C.L.

2004-01-01

In this study, the compressive behavior of Ti-6Al-4V/TiC composites considered for ballistic applications was examined at strain rates of 0.1, 1.0, and 10 s-1. As little as 1 vol% of particulate TiC provided nearly a 25% increase in strength in Ti-6Al-4V/TiC composites over that of the monolithic Ti-6Al-4V, while subsequent additions of TiC did not provide proportional benefit. The mechanisms responsible for such a significant increase in strength were investigated for the first time in this study. Microscopy (optical, SEM, TEM) aided in identifying the possible strengthening mechanisms that are typically important to the strength of metal matrix composites. These mechanisms include grain size and subgrain size refinement and an increase in dislocation density, all of which can occur during processing. Two other important mechanisms are thermal mismatch strains and load transfer from the matrix to the particle; the contribution of these mechanisms to the strength of the composite was evaluated using the Eshelby approach. A quantitative comparison of the mechanisms listed clearly showed that none of them was responsible for the large increase in strength with only 1vol%TiC in Ti-6Al-4V. The results from this study show for the first time that carbon in solution is, by far, the most potent strengthening mechanism in the Ti-6Al-4V/TiC particulate composites

Pitting Corrosion of Ni3(Si,Ti+4Al Intermetallic Compound at Various Chloride Concentrations

Directory of Open Access Journals (Sweden)

Gadang Priyotomo

2014-04-01

Full Text Available The pitting corrosion of Ni3(Si,Ti with 4 at% Al consisting of two regions of a Ni3(Si,Ti single-phase of L12 structure and two phases of L12 and fcc Niss was investigated as function of chloride concentrations by using electrochemical method, scanning electron microscope and energy dispersive X-Ray spectroscopy in neutral sodium chloride solutions at 293 K.  In addition, the pitting corrosion of Ni3(Si,Ti and  type C276 alloy were also studied under the same experimental condition for comparison.  The pitting potential obtained for the Ni3(Si,Ti with 4 at%Al decreased with increasing chloride concentration.  The specific pitting potential and pitting potential of Ni3(Si,Ti with 4at%, Ni3(Si,Ti and C276 were the lowest, the moderate and the highest, respectively, which means that the pitting corrosion resistance of Ni3(Si,Ti was higher than Ni3(Si,Ti with 4at% Al, but lower than that of C276.  A critical chloride concentration of Ni3(Si,Ti with 4at% Al was found to be lower than that of Ni3(Si,Ti.  The Pitting corrosion of Ni3(Si,Ti with 4at% Al occurred in the two phase mixture (L12 + Niss.

Melting and casting of FeAl-based cast alloy

Energy Technology Data Exchange (ETDEWEB)

Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

1998-11-01

The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

The critical effect of Fe on the grain refinement of aluminium via Al-5Ti-1B addition

International Nuclear Information System (INIS)

Zhang, Y; Ma, N

2016-01-01

The influence of Fe on the nucleation potency of TiB 2 particles was investigated by employing grain refinement of high purity aluminium in this study. Experiment results showed that without Fe, high purity aluminium cannot be refined by 0.8wt.% addition of Al-5Ti-1B. However, high purity aluminium containing 0.08wt.% Fe can be refined effectively by 0.2wt.% addition of Al-5Ti-1B, its grain size was about 206µm in diameter. Fine equiaxed grains of about 153µm in diameter can be obtained for high purity aluminium containing 0.08wt.% Fe and 0.006wt.% Ti. Grain refinement mechanism should include nucleation and dendrite remelting and multiplication. Both nucleation and dendrite remelting and multiplication played essential role on the grain refinement of aluminium. The effect of Fe was linked to increase active nuclei by segregation on TiB 2 surface and then to promote nucleation of α-Al. The performance of Ti was to enhance the dendrite remelting and multiplication by forming small conglomeration zones of Ti atoms concentrated around TiB 2 particles. (paper)

Effects of iron on intermetallic compound formation in scandium modified Al–Si–Mg Alloys

Energy Technology Data Exchange (ETDEWEB)

Patakham, Ussadawut [National Metal and Materials Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@mail.kmutt.ac.th [Production Engineering Department, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

2014-12-15

Highlights: • Iron reduces the modification effects of scandium in Al–Si–Mg alloys. • Morphologies of Sc-rich intermetallic phases vary with Fe and Sc contents and the cooling rates. • Sc neutralizes effects of Fe by changing Fe-rich intermetallic phases from platelets to more cubic. - Abstract: In general, iron has a strong tendency to dissolve in molten aluminum. Iron has very low solid solubility in aluminum–silicon casting alloys, so it will form intermetallic compounds that cause detrimental effects on mechanical properties. In this work, the effects of iron on intermetallic compound formations in scandium modified Al–Si–Mg alloys were studied. There were two levels of iron addition (0.2 and 0.4 wt.%) and two levels of scandium addition (0.2 and 0.4 wt.%). We found that the effects of scandium modification decreased with increasing iron addition. The morphologies of the complex intermetallic compounds were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques. It was found that scandium changes the morphology of Fe-rich intermetallic compounds from β-phase (plate-like) to α-phase, which reduces the harmful effects of β-phase.

Fine structure at the diffusion welded interface of Fe3Al/Q235 ...

Indian Academy of Sciences (India)

Unknown

iron lattice sites (Fair and Wood 1994). 3.2 TEM morphology at the diffusion joint of. Fe3Al/Q235. For the welding of dissimilar materials, the element diffusion and phase formed at the interface of dissimilar. Table 1. Chemical composition and thermophysical properties of Fe3Al intermetallic compound. Chemical composition ...

Characteristics microstructure and microhardness of cast Ti-6Al-4V ELI for biomedical application submitted to solution treatment

Science.gov (United States)

Damisih, Jujur, I. Nyoman; Sah, Joni; Agustanhakri, Prajitno, Djoko Hadi

2018-05-01

Ti 6Al-4V ELI (Extra Low Interstitial)alloy containing 6wt% of aluminum, 4wt% of vanadium with controlled level of iron and oxygen is one of most popular alloy employed in biomedical applications as implant material. Heat treatment process for titanium alloys becomes important and could be performed by some of different ways in order to develop microstructure as well as its properties. The objective of this paper is to study the effects of solution treatment temperature on microstructure and mechanical properties of as-cast Ti-6Al-4V ELI especially microhardness value. The alloy was melted by single arc melting furnace with a water-cooled copper crucible hearth under argon atmosphere and then casted. It was heat treated through solution treatment at 3 (three) different temperaturesi.e. 850°C, 950°C and 1050°C in an argon gas atmosphere for around 30 minutes. After solution treatment, samples were water quenched and then aged at temperature of 500°C for 4 hours. To investigate its microstructure, the alloy was investigated under optical microscope and scanning electron microscope (SEM). It was observed Widmanstätten microstructure consisting of mixture α and β phase with basket-weave pattern. The Vickers microhardness test was performed and the results exhibited the optimum value was obtained at temperature of 950°C of solution treatment. From the observation, it revealed that the heat treatment has substantial effect on microstructural properties where microhardness increased due to formation of α' martensite structure. It was showed also that solution treatment followed by aging could improve mechanical properties especially microhardness value of Ti-6Al-4V ELI alloy. These results were suggesting the optimized conditions of heat treatment to obtain the best microstructure properties and microhardness value.

Preparation of TiC/Ni3Al Composites by Upward Melt Infiltration

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

TiC/Ni3Al composites have been prepared using upward infiltration method. The densificstion was performed by both Ni3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni3Al has been evidenced by finding Ni3(Al,Ti)C after fast cooling in the TiC/Ni3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni3Al composite processed by upward infiltration had a flexural strength of 1476 Mpa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 Mpa(m). Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.

Research on microstructure properties of the TiC/Ni-Fe-Al coating prepared by laser cladding technology

Science.gov (United States)

Jiao, Junke; Xu, Zifa; Zan, Shaoping; Zhang, Wenwu; Sheng, Liyuan

2017-10-01

In this paper, the laser cladding method was used to preparation the TiC reinforced Ni-Fe-Al coating on the Ni base superalloy. The Ti/Ni-Fe-Al powder was preset on the Ni base superalloy and the powder layer thickness is 0.5mm. A fiber laser was used the melting Ti/Ni-Fe-Al powder in an inert gas environment. The shape of the cladding layer was tested using laser scanning confocal microscope (LSCM) under different cladding parameters such as the laser power, the melting velocity and the defocused amount. The microstructure, the micro-hardness was tested by LSCM, SEM, Vickers hardness tester. The test result showed that the TiC particles was distributed uniformly in the cladding layer and hardness of the cladding layer was improved from 180HV to 320HV compared with the Ni-Fe-Al cladding layer without TiC powder reinforced, and a metallurgical bonding was produced between the cladding layer and the base metal. The TiC powder could make the Ni-Fe-Al cladding layer grain refining, and the more TiC powder added in the Ni-Fe-Al powder, the smaller grain size was in the cladding layer.

Microstructural characterization and compression properties of TiC0.61/Cu(Al) composite synthesized from Cu and Ti3AlC2 powders

International Nuclear Information System (INIS)

Huang, Zhenying; Bonneville, Joel; Zhai, Hongxiang; Gauthier-Brunet, Veronique

2014-01-01

Highlights: • Submicro-layered TiC 0.61 /Cu(Al) nanocomposite. • MAX phase. • High yield stress. • Deformation mechanism. - Abstract: A new submicro-layered TiC 0.61 /Cu(Al) composite has been prepared by hot-pressing a mixture of 50 vol.% Ti 3 AlC 2 and 50 vol.% Cu powders at 1150 °C and 30 MPa. It is shown that the initial reinforcement Ti 3 AlC 2 particles have, after synthesis, an unusual microstructure, which consists of submicron-thick layers of TiC 0.61 and Cu(Al) alloy. Both the width of the TiC 0.61 and Cu(Al) layers are ∼150 nm. Thus, the Ti 3 AlC 2 particles are decomposed into the TiC 0.61 phase, while the additional Al atoms provided by Ti 3 AlC 2 diffuse into the molten Cu matrix at high temperature. Compression tests were performed at constant strain rate in the temperature range 20–800 °C. The new designed TiC 0.61 /Cu(Al) composite has both a high yield stress, σ 0.2 measured at 0.2% strain offset, and a high ultimate compressive strength, σ UCS , which is attributed to strong interface bonding between TiC 0.61 and Cu(Al) phase. For instance, at 20 and 200 °C, σ 0.2 is 770 MPa and 700 MPa, while σ UCS is 1.18 GPa and 1 GPa, respectively. Plastic deformation takes place in the Cu(Al) matrix. Wavy slip lines are observed indicating that cross-slip could be the dominant deformation mechanism

Oxidation Resistance of Fe3Al/TiC Composite at High Temperature%Fe3Al/TiC复合材料的高温抗氧化性能

Institute of Scientific and Technical Information of China (English)

范敏; 鲍剑斌

2003-01-01

研究了Fe3Al/TiC复合材料的高温抗氧化性能.结果表明:Fe3Al/TiC复合材料在950℃的氧化动力学特征均近似服从抛物线规律,并且随TiC含量增加,Fe3Al/TiC复合材料的高温抗氧化性能降低.

Lanthanum hexaboride as advanced structural refiner/getter in TiAl-based refractory intermetallics

Energy Technology Data Exchange (ETDEWEB)

Kartavykh, A.V., E-mail: karta@korolev-net.ru [Technological Institute for Superhard and Novel Carbon Materials (TISNCM), 7a Centralnaya str., 142190 Troitsk, Moscow (Russian Federation); National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation); Asnis, E.A.; Piskun, N.V.; Statkevich, I.I. [The E.O. Paton Electric Welding Institute, 11 Bozhenko str., 03680 Kyiv (Ukraine); Gorshenkov, M.V.; Tcherdyntsev, V.V. [National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation)

2014-03-05

Highlights: • Fist application of LaB{sub 6} additive in TiAl-based intermetallics casting. • Pilot synthesis/casting and study of selected TiAl(Nb,Cr,Zr)B,La alloys set. • Dual effect observed: phase structure refinement and oxygen impurity removal. • Co-precipitation of TiB and La{sub 2}O{sub 3} in melt: 2LaB{sub 6} + 12Ti + 3O → 12TiB↓ + La{sub 2}O{sub 3}↓. • Features of structure refinement and oxygen gettering mechanisms reported. -- Abstract: The work is aimed at the study of the formation and refinement of microstructure appearing in the solidifying refractory TiAl-based intermetallics being inoculated with precise boron addition. The novelty of research consists in test application of lanthanum hexaboride (LaB{sub 6}) ligature within semi-continuous electron beam casting process of selected alloys. Two ingots with nominal compositions Ti–44Al–5Nb–2Cr–1.5Zr–0.4B–0.07La and Ti–44Al–5Nb–1Cr–1.5Zr–1B–0.17La (at.%) have been synthesized and cast along with the reference alloy Ti–44Al–5Nb–3Cr–1.5Zr. Their comparative examination suggests (i) essential microstructural phase refinement effect coupled with (ii) threefold/fourfold decrease of background content of undesirable residual oxygen impurity in both alloys containing LaB{sub 6}. This advanced dual activity (i–ii) of LaB{sub 6} is explained by its complete dissolution, dissociation and following re-precipitation of effective Ti-based monoboride nucleants of orthorhombic B27 structure, those being accompanied by strong internal gettering of dissolved oxygen from the melt and from boride-inoculated solid α{sub 2}-Ti{sub 3}Al phase with liberated elemental lanthanum. The phase composition and structure of cast alloys; state and characterization of newly precipitated TiB boride; features of La{sub 2}O{sub 3} micro/nano-dimensional precipitation and oxygen gettering mechanism are reported and discussed.

Spark plasma sintering of titanium aluminide intermetallics and its composites

Science.gov (United States)

Aldoshan, Abdelhakim Ahmed

Titanium aluminide intermetallics are a distinct class of engineering materials having unique properties over conventional titanium alloys. gamma-TiAl compound possesses competitive physical and mechanical properties at elevated temperature applications compared to Ni-based superalloys. gamma-TiAl composite materials exhibit high melting point, low density, high strength and excellent corrosion resistance. Spark plasma sintering (SPS) is one of the powder metallurgy techniques where powder mixture undergoes simultaneous application of uniaxial pressure and pulsed direct current. Unlike other sintering techniques such as hot iso-static pressing and hot pressing, SPS compacts the materials in shorter time (< 10 min) with a lower temperature and leads to highly dense products. Reactive synthesis of titanium aluminide intermetallics is carried out using SPS. Reactive sintering takes place between liquid aluminum and solid titanium. In this work, reactive sintering through SPS was used to fabricate fully densified gamma-TiAl and titanium aluminide composites starting from elemental powders at different sintering temperatures. It was observed that sintering temperature played significant role in the densification of titanium aluminide composites. gamma-TiAl was the predominate phase at different temperatures. The effect of increasing sintering temperature on microhardness, microstructure, yield strength and wear behavior of titanium aluminide was studied. Addition of graphene nanoplatelets to titanium aluminide matrix resulted in change in microhardness. In Ti-Al-graphene composites, a noticeable decrease in coefficient of friction was observed due to the influence of self-lubrication caused by graphene.

Microstructure and wear behavior of {gamma}/Al{sub 4}C{sub 3}/TiC/CaF{sub 2} composite coating on {gamma}-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

Energy Technology Data Exchange (ETDEWEB)

Liu Xiubo [School of Mechanical and Electronic Engineering, 178 Ganjiang East Road, Soochow University, Suzhou 215021 (China)], E-mail: liubobo0828@yahoo.com.cn; Shi Shihong [School of Mechanical and Electronic Engineering, 178 Ganjiang East Road, Soochow University, Suzhou 215021 (China); Guo Jian [School of Materials and Chemical Engineering, Zhongyuan Institute of Technology, 41 Zhongyuan West Road, Zhengzhou 450007 (China); Fu Geyan; Wang Mingdi [School of Mechanical and Electronic Engineering, 178 Ganjiang East Road, Soochow University, Suzhou 215021 (China)

2009-03-15

As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF{sub 2} in the preparation of precursor NiCr-Cr{sub 3}C{sub 2}-CaF{sub 2} mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al{sub 4}C{sub 3} carbides reinforcement as well as fine isolated spherical CaF{sub 2} solid lubrication particles uniformly dispersed in the NiCrAlTi ({gamma}) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF{sub 2} and the increasing of it's wettability with the NiCrAlTi ({gamma}) matrix during the laser cladding process.

Neutralization of the negative influence of iron and silicon on the mechanical properties of aluminium casting alloys

International Nuclear Information System (INIS)

Zolotorevsky, V.S.; Axenov, A.A.; Belov, N.A.

1990-01-01

In most of casting aluminium alloys iron is a harmful impurity due to the appearance of rough particles with needle, plate or sceleton shapes of intermetallic compounds during crystallization. As a result of it the plasticity, fracture toughness and sometimes the strength are decreased

Thermal migration of iron implanted in aluminium at high doses

International Nuclear Information System (INIS)

Asundi, V.K.; Joshi, M.C.; Deb, S.K.; Soud, D.K.; Kulkarni, V.N.; Sundararaman, M.

1978-01-01

The anneal behaviour of the Fe-Al metastable system produced by implantation of Fe + ions at 30 keV has been reported. The implant concentrations between 18-42 at percent have been chosen, in order to exceed the normal solid solubility of Fe in Al by about three orders of magnitude. Isothermal annealing has been done under vacuum (55 x 10 -6 Torr) at 400deg C and 570 deg C. The iron depth profiles have been determined, by Rutherford backscattering of 2 MeV He + ions. It has been found that 1) as annealing proceeds, all specimens show rapid enhanced diffusion initially (upto about 30 m), followed by a much slower diffusion as iron ions migrate inwards (2) at implant concentrations 23 at percent, double peaks appear in iron depth profiles, followed by rapid migration of diffused iron towards surface and (3) at still higher anneal times, the out-diffused iron moves inward again. This kind of out-diffusion behaviour in a metallic system has not been reported earlier in the literature. Also, the presence of Fe 4 Al 13 has been identified as terminal phase, using x-ray diffraction techniques. (K.B.)

INFLUENCE OF IRON CONTENT AND PLASTIC DEFORMATION ...

African Journals Online (AJOL)

eobe

MECHANICAL PROPERTIES OF 8011-TYPE Al-Fe-Si ALLOY. O. H. Yakubu1, I. ... properties such as formability, corrosion, light weight and also ... In aluminium alloy, a large number of iron-containing intermetallic ... conditions and alloy composition. Although ... and tensile behaviour of 7075 aluminium alloy [8] observed ...

A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

International Nuclear Information System (INIS)

Ma Xiaoguang; Liu Xiangfa; Ding Haimin

2009-01-01

Because flake-like TiAl 3 particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl 3 particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of α-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption

Corrosion behavior of Fe3Al intermetallics with addition of lithium, cerium and nickel in 2.5 % SO2+N2 at 900 degree centigrade

International Nuclear Information System (INIS)

Luna-Ramirez, A.; Porcayo-Calderon, J.; Martinez-Villafane, A.; Gonzalez-Rodriguez, J. G.; Chaon-Nava, J. G.

2012-01-01

The corrosion behavior of Fe 3 Al-type intermetallic alloys with addition of 1 at. % cerium, lithium and nickel at high temperature has been studied. The various alloys were exposed to an environment composed of 2.5 % SO 2 +N 2 at 900 degree centigrade for 48 h. For all the intermetallic tested, the corrosion kinetics showed a parabolic behavior. The alloy, which showed less corrosion rate, was the Fe3AlNi alloy, being Fe 3 AlCeLi the alloy with the highest corrosion rate. For the various alloys, energy dispersive X-ray spectroscopy analysis, EDS, on the developed scale only detected aluminum, oxygen, and traces of iron and cerium, suggesting the formation of alumina as main component. The intermetallic alloys showed oxide cracking and spalling. The intermetallic chemical composition played an important role in defining the oxide scale morphology and the extent of damage. (Author) 39 refs.

The role of Zr and T6 heat treatment on microstructure evolution and hardness of AlSi9Cu3(Fe diecasting alloy

Directory of Open Access Journals (Sweden)

Vončina M.

2017-01-01

Full Text Available The microstructure features and hardness of AlSi9Cu3(Fe die casting alloy was investigated in the presence of Zr addition. The cast alloys were undergone the solutionizing treatment 2 h at 500°C followed by artificial aging at 180°C for 5 h. Optical microscopy and electron micro-analyzer were used to study the formation of different intermetallic phases. The hardness was tested for all samples at 25°C. The results revealed that the intermetallic phase, based on (Al,Si(Zr,Ti, forms when Zr is added in the investigated alloy, while the T6 heat treatment does not influence on the formation of Zr-bearing phase. Results also indicate that the hardness slightly increases in the AlSi9Cu3 alloy in as-cast state when Zr is added, while after T6 heat treatment increases by 50% in the alloy without Zr and by 61% in the alloy with Zr addition.

Role of iron in Na {sub 1.5}Fe {sub 0.5}Ti {sub 1.5}(PO {sub 4}) {sub 3}/C as electrode material for Na-ion batteries studied by operando Mössbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Difi, Siham [Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS (France); Saadoune, Ismael [Université Cadi Ayyad, Laboratoire de Chimie des Matériaux et de l’Environnement (Morocco); Sougrati, Moulay Tahar [Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS (France); Hakkou, Rachid [Université Cadi Ayyad, Laboratoire de Chimie des Matériaux et de l’Environnement (Morocco); Edstrom, Kristina [Uppsala University, Department of Chemistry - Ångström laboratory (Sweden); Lippens, Pierre-Emmanuel, E-mail: lippens@univ-montp2.fr [Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS (France)

2016-12-15

The role of iron in Na {sub 1.5}Fe {sub 0.5}Ti {sub 1.5}(PO {sub 4}){sub 3}/C electrode material for Na batteries has been studied by {sup 57}Fe Mössbauer spectroscopy in operando mode. The potential profile obtained in the galvanostatic regime shows three plateaus at different voltages due to different reaction mechanisms. Two of them, at 2.2 and 0.3 V vs Na {sup +}/Na {sup 0}, have been associated to redox processes involving iron and titanium in Na {sub 1.5}Fe {sub 0.5}Ti {sub 1.5}(PO {sub 4}){sub 3}. The role of titanium was previously elucidated for NaTi {sub 2}(PO {sub 4}){sub 3} and the effect of the substitution of Fe for Ti was investigated with {sup 57}Fe Mössbauer spectroscopy. We show that iron is an electrochemically active center at 2.2 V with the reversible Fe {sup 3+}/Fe {sup 2+} transformation and then remains at the oxidation state Fe {sup 2+} along the sodiation until the end of discharge at 0 V.

A novel method to fabricate TiAl intermetallic alloy 3D parts using additive manufacturing

Directory of Open Access Journals (Sweden)

J.J.S. Dilip

2017-04-01

Full Text Available The present work explores the feasibility of fabricating porous 3D parts in TiAl intermetallic alloy directly from Ti–6Al–4V and Al powders. This approach uses a binder jetting additive manufacturing process followed by reactive sintering. The results demonstrate that the present approach is successful for realizing parts in TiAl intermetallic alloy.

A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

Energy Technology Data Exchange (ETDEWEB)

Ma Xiaoguang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn; Ding Haimin [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2009-03-05

Because flake-like TiAl{sub 3} particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl{sub 3} particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of {alpha}-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption.

Microstructural, mechanical characterisation and fractography of As-cast Ti-Al alloy

International Nuclear Information System (INIS)

Hamzah, E.; Ong, W.R.; Tamin, M.N.

2007-01-01

The effect of alloying element, namely chromium (Cr) on the microstructures, mechanical characterization and fracture surface of gamma titanium aluminide (Ti Al) has been studied. Micro-hardness and fatigue crack growth tests were performed on as-cast samples with composition of Ti-48at%Al and Ti-48%Al-2at%Cr. Prior to the micro-hardness tests; samples were metallurgically prepared for microstructural and structural analysis using optical microscope and scanning electron microscope. Field emission scanning electron microscope (FESEM) technique was employed to investigate the fracture surface of sample after fatigue crack growth test. Micro-hardness tests results showed increasing hardness value of Ti-48Al alloys when chromium is added. Both titanium aluminide alloys exhibited a nearly lamellae microstructure. However, finer laths of plates in lamellar structure have been observed in Ti-48at%Al-2at%Cr. FESEM micrograph of surface fracture indicates a mixed mode of failure for both alloys. (author)

Barium aluminides BaxAl5(x=3,3.5,4)

International Nuclear Information System (INIS)

Jehle, Michael; Scherer, Harald; Wendorff, Marco; Roehr, Caroline

2009-01-01

Three aluminides of the series Ba x Al 5 (x=3,3.5,4) were synthesized from stoichiometric ratios of the elements in Ta crucibles. The crystal structure of the new compound Ba 7 Al 10 was determined using single crystal X-ray data (space group R3-barm, a=604.23(9), c=4879.0(12)pm, Z=3, R1=0.0325). The compound exhibits Al Kagome (3.6.3.6.) nets in which half of the triangles form the basis of trigonal bipyramids Al 5 . The apical Al are thus three-bonded assuming a charge of -2 ( 27 Al-NMR chemical shift δ=660pm), whereas the Al atoms of the basal triangle (i.e. of the Kagome net) are four-bonded and thus of formal charge -1(δ=490ppm). The total charge of the anion is thus exactly compensated by the Ba cations, i.e. the compound can be interpreted as an electron precise Zintl phase, exhibiting a distinct pseudo-band gap at the Fermi level of the calculated tDOS. According to the total formula, the structure displays a combination the stacking sequences of Ba 3 Al 5 and Ba 4 Al 5 , the structures of which have been redetermined with current methods (both hexagonal with space group P6 3 /mmc; Ba 3 Al 5 : a=606.55(7), c=1461.8(2)pm, Z=2, R1=0.0239; Ba 4 Al 5 : a=609.21(7), c=1775.8(3)pm, Z=2, R1=0.0300). These three compounds with slightly different electron counts but similar polyanions allow to compare the bond lengths, the electronic structures and the overall bonding situation in dependence of positive or negative deviation of the electron count in relation to the novel formally electron precise Zintl compound Ba 7 Al 10 . - Al 5 layers of Kagome nets in the new binary electron precise Zintl compound Ba 3.5 Al 5 , also found in Ba 3 Al 5 and Ba 4 Al 5 .

A study on the corrosion and erosion behavior of electroless nickel and TiAlN/ZrN duplex coatings on ductile iron

Energy Technology Data Exchange (ETDEWEB)

Lin, Chung-Kwei [School of Dental Technology, Taipei Medical University, Taipei 110, Taiwan (China); Hsu, Cheng-Hsun, E-mail: chhsu@ttu.edu.tw [Department of Materials Engineering, Tatung University, Taipei 104, Taiwan (China); College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Cheng, Yin-Hwa [Department of Materials Engineering, Tatung University, Taipei 104, Taiwan (China); Ou, Keng-Liang [College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Department of Mechanical Engineering, National Central University, Taoyuan 320, Taiwan (China); Lee, Sheng-Long [Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China)

2015-01-01

Highlights: • Electroless nickel was used as an interlayer for TiAlZrN-coated ductile iron. • The duplex coatings evidently improved corrosion resistance of ductile iron. • The duplex coated ductile iron showed a good erosion resistance. - Abstract: This study utilized electroless nickel (EN) and cathodic arc evaporation (CAE) technologies to deposit protective coatings onto ductile iron. Polarization corrosion tests were performed in 3.5 wt.% sodium chloride, and also erosion tests were carried out by using Al{sub 2}O{sub 3} particles (∼177 μm in size and Mohr 7 scale) of about 5 g. Surface morphologies of the corroded and eroded specimens were observed separately. To further understand the coating effects on both the corrosive and erosive behavior of ductile iron, coating structure, morphology, and adhesion were analyzed using X-ray diffractormeter, scanning electron microscopy, and Rockwell-C indenter, respectively. The results showed that the EN exhibited an amorphous structure while the CAE-TiAlN/ZrN coating was a multilayered nanocrystalline. When the TiAlN/ZrN coated specimen with EN interlayer could effectively increase the adhesion strength between the CAE coating and substrate. Consequently, the combination of TiAlN/ZrN and EN delivered a better performance than did the monolithic EN or TiAlN/ZrN for both corrosion and erosion protection.

A study on the corrosion and erosion behavior of electroless nickel and TiAlN/ZrN duplex coatings on ductile iron

International Nuclear Information System (INIS)

Lin, Chung-Kwei; Hsu, Cheng-Hsun; Cheng, Yin-Hwa; Ou, Keng-Liang; Lee, Sheng-Long

2015-01-01

Highlights: • Electroless nickel was used as an interlayer for TiAlZrN-coated ductile iron. • The duplex coatings evidently improved corrosion resistance of ductile iron. • The duplex coated ductile iron showed a good erosion resistance. - Abstract: This study utilized electroless nickel (EN) and cathodic arc evaporation (CAE) technologies to deposit protective coatings onto ductile iron. Polarization corrosion tests were performed in 3.5 wt.% sodium chloride, and also erosion tests were carried out by using Al 2 O 3 particles (∼177 μm in size and Mohr 7 scale) of about 5 g. Surface morphologies of the corroded and eroded specimens were observed separately. To further understand the coating effects on both the corrosive and erosive behavior of ductile iron, coating structure, morphology, and adhesion were analyzed using X-ray diffractormeter, scanning electron microscopy, and Rockwell-C indenter, respectively. The results showed that the EN exhibited an amorphous structure while the CAE-TiAlN/ZrN coating was a multilayered nanocrystalline. When the TiAlN/ZrN coated specimen with EN interlayer could effectively increase the adhesion strength between the CAE coating and substrate. Consequently, the combination of TiAlN/ZrN and EN delivered a better performance than did the monolithic EN or TiAlN/ZrN for both corrosion and erosion protection

Semisolid casting with ultrasonically melt-treated billets of Al-7mass%Si alloys

Directory of Open Access Journals (Sweden)

Yoshiki Tsunekawa

2012-02-01

Full Text Available The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compound of モ-Al5FeSi turns into harmless form without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass%Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ìC, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary メ-Al is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in the temperature range of 630 ìC to 605 ìC, the primary メ-Al transforms itself from dendrite into fine globular in morphology. The coarse plate-like モ-Al5FeSi compound becomes markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ìC, does not appreciably affect the size of モ-Al5FeSi compounds; however, it affects the solid primary メ-Al morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast Al-7mass%Si-2mass%Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with

Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

Science.gov (United States)

Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

2016-05-01

Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

Granulation of Cu-Al-Fe-Ni Bronze

Directory of Open Access Journals (Sweden)

Pisarek B.P.

2014-08-01

Full Text Available With the increase in wall thickness of the casting of iron-nickel-aluminium-bronze, by the reduction of the cooling rate the size of κII phase precipitates increases. This process, in the case of complex aluminium bronzes with additions of Cr, Mo and W is increased. Crystallization of big κII phase, during slow cooling of the casting, reduces the concentration of additives introduced to the bronze matrix and hardness. Undertaken research to develop technology of thick-walled products (g> 6 mm of complex aluminium bronzes. Particular attention was paid to the metallurgy of granules. As a result, a large cooling speed of the alloy, and also high-speed solidification casting a light weight of the granules allows: to avoid micro-and macrosegregation, decreasing the particle size, increase the dispersion of phases in multiphase alloys. Depending on the size granules as possible is to provide finished products with a wall thickness greater than 6 mm by infiltration of liquid alloy of granules (composites. Preliminary studies was conducted using drip method granulate of CuAl10Fe5Ni5 bronze melted in a INDUTHERM-VC 500 D Vacuum Pressure Casting Machine. This bronze is a starting alloy for the preparation of the complex aluminium bronzes with additions of Cr, Mo, W and C or Si. Optimizations of granulation process was carried out. As the process control parameters taken a casting temperature t (°C and the path h (mm of free-fall of the metal droplets in the surrounding atmosphere before it is intensively cooled in a container of water. The granulate was subjected to a sieve analysis. For the objective function was assume maximize of the product of Um*n, the percentage weight “Um” and the quantity of granules ‘n’ in the mesh fraction. The maximum value of the ratio obtained for mesh fraction a sieve with a mesh aperture of 6.3 mm. In the intensively cooled granule of bronze was identified microstructure composed of phases: β and fine bainite

Microstructure of Al-Si Slurry Coatings on Austenitic High-Temperature Creep Resisting Cast Steel

Directory of Open Access Journals (Sweden)

Agnieszka E. Kochmańska

2018-01-01

Full Text Available This paper presents the results of microstructural examinations on slurry aluminide coatings using scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. Aluminide coatings were produced in air atmosphere on austenitic high-temperature creep resisting cast steel. The function of aluminide coatings is the protection of the equipment components against the high-temperature corrosion in a carburising atmosphere under thermal shock conditions. The obtained coatings had a multilayered structure composed of intermetallic compounds. The composition of newly developed slurry was powders of aluminium and silicon; NaCl, KCl, and NaF halide salts; and a water solution of a soluble glass as an inorganic binder. The application of the inorganic binder in the slurry allowed to produce the coatings in one single step without additional annealing at an intermediate temperature as it is when applied organic binder. The coatings were formed on both: the ground surface and on the raw cast surface. The main technological parameters were temperature (732–1068°C and time of annealing (3.3–11.7 h and the Al/Si ratio (4–14 in the slurry. The rotatable design was used to evaluate the effect of the production parameters on the coatings thickness. The correlation between the technological parameters and the coating structure was determined.

Tetragonal phase in Al-rich region of U-Fe-Al system

International Nuclear Information System (INIS)

Meshi, L.; Zenou, V.; Ezersky, V.; Munitz, A.; Talianker, M.

2005-01-01

A new ternary aluminide U 2 FeAl 20 with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m

Principles of Structure and Phase Composition Formation in Composite Master Alloys of the Al-Ti-B/B4c Systems Used for Aluminum Alloy Modification

Science.gov (United States)

Zhukov, I. A.; Promakhov, V. V.; Matveev, A. E.; Platov, V. V.; Khrustalev, A. P.; Dubkova, Ya. A.; Vorozhtsov, S. A.; Potekaev, A. I.

2018-03-01

The principles of formation of structure and properties of materials produced by self-propagating hightemperature synthesis (SHS) from the Al-Ti-B/B4C powder systems are identified. It is shown that the SHSmaterials produced from the Al-Ti-B powder systems consist of a TiAl intermetallic matrix with inclusions of titanium diboride particles. It is found out that an introduction of 1 wt.% of TiB2 particles into the melt of the AD35 aluminum alloy allows reducing the grain size from 620 to 220 μm and gives rise to an increase in the ultimate tensile strength of as-cast specimens from 100 to 145 MPa and in the plasticity from 7 to 9%.

Environmental embrittlement of intermetallic compounds in Fe-Al alloys

Institute of Scientific and Technical Information of China (English)

张建民; 张瑞林; S.H.YU; 余瑞璜

1996-01-01

First,it is proposed that hydrogen atoms occupy the interstitial sites in Fe3Al and FeAl.Then the environmental embrittlement of intermetallic compounds in Fe-Al alloys is studied in the light of calculated valence electron structures and bond energy of Fe3Al and FeAl containing hydrogen atoms.From the analyses it is found that the states of metal atoms will change,in which more lattice electrons will become covalent electrons to bond with hydrogen atoms when the atomic hydrogen diffuses into the intermetallic compounds in Fe-Al alloys,which will result in the decrease of local metallicity in Fe3Al and FeAl.Meanwhile,it is found that the crystal will easily cleave since solute hydrogen bonds with metal atoms and severely anisotropic bonds form.As a conclusion,these factors result in the environmental embrittlement of Fe3Al and FeAl.

Interfacial reaction in SiC_f/Ti-6Al-4V composite by using transmission electron microscopy

International Nuclear Information System (INIS)

Huang, Bin; Li, Maohua; Chen, Yanxia; Luo, Xian; Yang, Yanqing

2015-01-01

The interfacial reactions of continuous SiC fiber reinforced Ti-6Al-4V matrix composite (SiC_f/Ti-6Al-4V composite) and continuous SiC fiber coated by C reinforced Ti-6Al-4V matrix composite (SiC_f/C/Ti-6Al-4V composite) were investigated by using micro-beam electron diffraction (MBED) and energy disperse spectroscopy (EDS) on transmission electron microscopy (TEM). The sequence of the interfacial reactions in the as-processed and exposed at 900°C for 50h SiC_f/Ti-6Al-4V composites can be described as SiC||TiC||Ti_5Si_3 + TiC||Ti-6Al-4V and SiC||TiC||Ti_5Si_3||TiC||Ti_5Si_3||TiC||Ti_5Si_3||Ti-6Al-4V, respectively. Additionally, both in as-processed and exposed composites, Ti_3SiC_2 and Ti_3Si are absent at the interfaces. For the SiC_f/C/Ti-6Al-4V composite exposed at 900 °C for 50 h, the sequence of the interfacial reaction can be described as SiC||C||TiC_F||TiC_C||Ti-6Al-4V before C coating is completely consumed by interfacial reaction. When interfacial reaction consumes C coating completely, the sequence of the interfacial reaction can be described as SiC||TiC||Ti_5Si_3||TiC||Ti-6Al-4V. Furthermore, in SiC_f/C/Ti-6Al-4V composite, C coating can absolutely prevent Si diffusion from SiC fiber to matrix. Basing on these results, the model of formation process of the interfacial reaction products in the composites was proposed. - Highlights: • We obtained the sequence of the interfacial reactions in the as-processed and exposed at 900 °C for 50 h SiC_f/Ti-6Al-4 V composites as well as in the SiC_f/C/Ti-6Al-4 V composite exposed at 900 °C for 50 h. • We verified that both in as-processed and exposed SiC_f/Ti-6Al-4 V composites, Ti_3SiC_2 and Ti_3Si are absent at the interfaces. • Carbon coating can absolutely prevent silicon diffusion from SiC fiber to matrix. • Basing on these results, the model of formation process of the interfacial reaction products in the composites was proposed.

Laser alloying of AI with mixed Ni, Ti and SiC powders

CSIR Research Space (South Africa)

Mabhali, Luyolo AB

2010-03-01

Full Text Available composite (MMC) is formed. The MMC layer has excellent hardness and wear resistance compared to the base alloy [9-13]. Man et al. [14] used a high power continuous wave Nd:YAG laser to alloy aluminium AA 6061 with preplaced NiTi (54 wt% Ni & 46 wt...Al, Ti3Al, SiC, Al and Si phases. The hardness increased from 75HV to 650HV due to the formation of the TiC particles and TiAl and Ti3Al intermetallics. Su and Lei [9] laser cladded Al-12wt%Si with a powder containing SiC and Al-12wt%Si in a 3...

Moessbauer effect measurements on the intermetallic compounds Ni3Al and Ni3Ge

International Nuclear Information System (INIS)

Drijver, J.W.; Woude, F. van der

1975-01-01

Moessbauer parameters obtained from room temperature emission and absorption spectra of Ni 3 Al and Ni 3 Ga processed by a computer assuming a singlet and a doublet are given. The doublet is due to iron or cobalt atoms at the nickel site. Quadrupole splitting at 57 Fe nuclei in Ni 3 Ga is larger than in Ni 3 Al, viz. 0.52 and 0.37 mm/sec, respectively. Isomer shift at the Al/Ga position is very close to -0.02 mm/sec found in metallic nickel. Also given are the hyperfine magnetic fields at 4.2 K. Considering the preference of 57 Co and 57 Fe atoms in the lattice, the field intensities at the nickel and aluminium sites are found to be 227 +- 1 and 238 +- 1 kOe, respectively. (Z.S.)

The mechanical and electronic properties of Al/TiC interfaces alloyed by Mg, Zn, Cu, Fe and Ti: First-principles study

International Nuclear Information System (INIS)

Sun, Ting; Wu, Xiaozhi; Wang, Rui; Li, Weiguo

2015-01-01

The adhesion and ductility of (100) and (110) Al/TiC interfaces alloyed by Mg, Zn, Cu, Fe, and Ti have been investigated using first-principles methods. Fe and Ti can enhance the adhesion of (100) and (110) interfaces. Mg and Zn have the opposite effect. Interfacial electronic structures have been created to analyze the changes of the work of adhesion. It is found that more charge is accumulated at interfaces alloyed by Fe and Ti compared with pure Al/TiC. There is also an obvious downward shift in the Fermi energy of Fe, Ti at the interface. Furthermore, the unstable stacking fault energies of the interfaces are calculated; the results demonstrate that the preferred slip direction is the 〈110〉 direction for (100) and (110) Al/TiC. Based on the Rice criterion of ductility, the results predict that Mg, Fe, and Ti are promising candidates for improving the ductility of Al/TiC interfaces. (paper)

Microstructures and mechanical properties of Fe-28Al-5Cr/TiC composites produced by hot-pressing sintering

International Nuclear Information System (INIS)

Zhang Xinghua; Yang Jun; Ma Jiqiang; Bi Qinling; Cheng Jun; Liang Yongmin; Liu Weimin

2011-01-01

Highlights: → The near fully dense Fe-28Al-5Cr/TiC composites are produced by hot-pressing sintering. → All the materials exhibit high compressive and bending strength. → Compressive strength increases but bending strength and ductility diminish with rising TiC amount in the composites. → Wear resistance significantly increases with rising TiC amount. - Abstract: The mechanical properties and microstructures of Fe-28Al-5Cr based composites reinforced with 15, 25, 35, 50 wt.% TiC ceramic particle, produced by hot-pressing sintering method, were investigated. The relative density of all the composites was up to 99%. The distribution of TiC was uniform in the composites. Results of XRD analysis showed that the composites were composed of TiC and disorder Fe 3 Al phases. All the materials exhibited very high strength of 1200-2000 MPa. The hardness and compressive strength of the composites increased obviously but compressive strain decreased gradually except 50% composite with increasing TiC content. The bending strength and deflection of the composites decreased significantly with increasing TiC content. The bending fracture surfaces of all the materials were examined using scanning electron microscopy (SEM). The fracture mode transformed gradually from tough dimple fracture mode to brittle cleavage facets crack mode with the increase of TiC content. Wear resistance of the Fe-28Al-5Cr alloy was also significantly improved by addition of TiC.

Molybdeno-Aluminizing of Powder Metallurgy and Wrought Ti and Ti-6Al-4V alloys by Pack Cementation process

International Nuclear Information System (INIS)

Tsipas, Sophia A.; Gordo, Elena

2016-01-01

Wear and high temperature oxidation resistance of some titanium-based alloys needs to be enhanced, and this can be effectively accomplished by surface treatment. Molybdenizing is a surface treatment where molybdenum is introduced into the surface of titanium alloys causing the formation of wear-resistant surface layers containing molybdenum, while aluminizing of titanium-based alloys has been reported to improve their high temperature oxidation properties. Whereas pack cementation and other surface modification methods have been used for molybdenizing or aluminizing of wrought and/or cast pure titanium and titanium alloys, such surface treatments have not been reported on titanium alloys produced by powder metallurgy (PM). Also a critical understanding of the process parameters for simultaneous one step molybdeno-aluminizing of titanium alloys by pack cementation and the predominant mechanism for this process have not been reported. The current research work describes the surface modification of titanium and Ti-6Al-4V prepared by PM by molybdeno-aluminizing and analyzes thermodynamic aspects of the deposition process. Similar coatings are also deposited to wrought Ti-6Al-4V and compared. Characterization of the coatings was carried out using scanning electron microscopy and x-ray diffraction. For both titanium and Ti-6Al-4V, the use of a powder pack containing ammonium chloride as activator leads to the deposition of molybdenum and aluminium into the surface but also introduces nitrogen causing the formation of a thin titanium nitride layer. In addition, various titanium aluminides and mixed titanium aluminium nitrides are formed. The appropriate conditions for molybdeno-aluminizing as well as the phases expected to be formed were successfully determined by thermodynamic equilibrium calculations. - Highlights: •Simultaneous co-deposition of Mo-Al onto powder metallurgy and wrought Ti alloy •Thermodynamic calculations were used to optimize deposition conditions

Molybdeno-Aluminizing of Powder Metallurgy and Wrought Ti and Ti-6Al-4V alloys by Pack Cementation process

Energy Technology Data Exchange (ETDEWEB)

Tsipas, Sophia A., E-mail: stsipas@ing.uc3m.es; Gordo, Elena

2016-08-15

Wear and high temperature oxidation resistance of some titanium-based alloys needs to be enhanced, and this can be effectively accomplished by surface treatment. Molybdenizing is a surface treatment where molybdenum is introduced into the surface of titanium alloys causing the formation of wear-resistant surface layers containing molybdenum, while aluminizing of titanium-based alloys has been reported to improve their high temperature oxidation properties. Whereas pack cementation and other surface modification methods have been used for molybdenizing or aluminizing of wrought and/or cast pure titanium and titanium alloys, such surface treatments have not been reported on titanium alloys produced by powder metallurgy (PM). Also a critical understanding of the process parameters for simultaneous one step molybdeno-aluminizing of titanium alloys by pack cementation and the predominant mechanism for this process have not been reported. The current research work describes the surface modification of titanium and Ti-6Al-4V prepared by PM by molybdeno-aluminizing and analyzes thermodynamic aspects of the deposition process. Similar coatings are also deposited to wrought Ti-6Al-4V and compared. Characterization of the coatings was carried out using scanning electron microscopy and x-ray diffraction. For both titanium and Ti-6Al-4V, the use of a powder pack containing ammonium chloride as activator leads to the deposition of molybdenum and aluminium into the surface but also introduces nitrogen causing the formation of a thin titanium nitride layer. In addition, various titanium aluminides and mixed titanium aluminium nitrides are formed. The appropriate conditions for molybdeno-aluminizing as well as the phases expected to be formed were successfully determined by thermodynamic equilibrium calculations. - Highlights: •Simultaneous co-deposition of Mo-Al onto powder metallurgy and wrought Ti alloy •Thermodynamic calculations were used to optimize deposition conditions

Effect of iron content on the structure and mechanical properties of Al25Ti25Ni25Cu25 and (AlTi)60-xNi20Cu20Fex (x=15, 20) high-entropy alloys

International Nuclear Information System (INIS)

Fazakas, É.; Zadorozhnyy, V.; Louzguine-Luzgin, D.V.

2015-01-01

Highlights: • Three new refractory alloys namely: Al 25 Ti 25 Ni 25 Cu 25 , Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 , were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al 25 Ti 25 Ni 25 C u25 Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al 25 Ti 25 Ni 25 Cu 25 , Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 alloys are relatively hard and ductile. Being heat treated at 973 K the Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

High temperature oxidation behavior of TiAl-based intermetallics

International Nuclear Information System (INIS)

Stroosnijder, M.F.; Sunderkoetter, J.D.; Haanappel, V.A.C.

1996-01-01

TiAl-based intermetallic compounds have attracted considerable interest as structural materials for high-temperature applications due to their low density and substantial mechanical strength at high temperatures. However, one major drawback hindering industrial application arises from the insufficient oxidation resistance at temperatures beyond 700 C. In the present contribution some general aspects of high temperature oxidation of TiAl-based intermetallics will be presented. This will be followed by a discussion of the influence of alloying elements, in particular niobium, and of the effect of nitrogen in the oxidizing environment on the high temperature oxidation behavior of such materials

Production of Al-Ti-C grain refiners with the addition of elemental carbon

International Nuclear Information System (INIS)

Gezer, Berke Turgay; Toptan, Fatih; Daglilar, Sibel; Kerti, Isil

2010-01-01

Grain refining process used in aluminium alloys, has an important role for preventing columnar, coarse grains and encouraging fine, equiaxed grain formation. Al-Ti-B grain refiners are widely used as aluminium grain refiners despite the problems in application Al-Ti-C refiners have an increasing demand in recent years. In the present work, Al-Ti-C grain refiners with different Ti:C ratios were produced by insitu method with the addition of elemental carbon. Microstructures were characterised by optic microscope and scanning electron microscope equipped with energy dispersive spectroscopy. The effects of temperature, holding time and Ti:C ratio on the grain refinement process were investigated and optimum conditions were determined.

Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

Science.gov (United States)

Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

2000-01-01

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr.ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Ti2Al(C, N) Solid Solution Reinforcing TiAl-Based Composites: Evolution of a Core-Shell Structure, Interfaces, and Mechanical Properties.

Science.gov (United States)

Song, Xiaojie; Cui, Hongzhi; Han, Ye; Ding, Lei; Song, Qiang

2018-05-16

In this work, Ti 2 Al(C, N) solid solution with lamellar structure-enhanced TiAl matrix composites was synthesized by vacuum arc melting, using bulk g-C 3 N 4 , Ti, and Al powders as raw materials. The phases, microstructures, interfaces, and mechanical properties were investigated. MAX phase of Ti 2 Al(C, N) solid solution with lamellar structure was formed. During the melting process, first, C 3 N 4 reacted with Ti to form Ti(C, N) by Ti + C 3 N 4 → Ti(C, N). Then Ti 2 Al(C, N) was formed by a peritectic reaction of TiAl(l) + Ti(C, N)(s) → Ti 2 Al(C, N). C 3 N 4 is the single reactant that provides C and N simultaneously to final product of Ti 2 Al(C, N). The interfaces of TiAl//Ti 2 Al(C, N) and Ti 2 Al(C, N)//Ti(C, N) display perfect orientation relationships with low misfit values. The microhardness, compressive strength, and strain of best-performing TiAl-10 mol % Ti 2 Al(C, N) composite were improved by 45%, 55.7%, and 50% compared with the TiAl alloy, respectively. Uniformly distributed Ti 2 Al(C, N) and unreacted Ti(C, N) particles contributed to the grain refinement and reinforcement of the TiAl matrix. Laminated tearing, particle pull-out, and the crack-arresting of Ti 2 Al(C, N) are crucial for the improvement in compressive strength and plasticity of the composites.

The effects of zirconium and carbon on the hot cracking resistance of iron aluminides. Topical report

Energy Technology Data Exchange (ETDEWEB)

Mulac, B.L.; Edwards, G.R. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering; David, S.A. [Oak Ridge National Lab., TN (United States)

1998-02-01

Iron aluminides have been of interest for about 60 years because of their good high temperature strengths (below 600{degrees}C) and excellent oxidation and sulfidation resistance, as well as their relatively low cost and conservation of strategic elements. These advantageous properties have driven the development of iron aluminides as potential structural materials. However, the industrial application of iron aluminides has been inhibited because of a sharp reduction in strength at temperatures higher than 600{degrees}C and low ductility at ambient temperatures due to hydrogen embrittlement. Oak Ridge National Laboratory has shown in recent years that room temperature properties of alloys containing 28% Al (all compositions are in atomic percent unless otherwise noted) can be improved through thermomechanical processing and alloying. Iron aluminides must have good weldability if they are to be used as structural materials. A coarse fusion zone microstructure is formed when iron aluminides are welded, increasing their susceptibility to cold cracking in water vapor. A recent study at Colorado School of Mines has shown that refining the fusion zone microstructure by weld pool oscillation effectively reduces cold cracking. Weld pool inoculation has been shown to refine fusion zone microstructures, but coarse carbide distribution caused this approach to reducing cold cracking to be ineffective.

Identification of intermetallic phases in a eutectic Al-Si casting alloy using electron backscatter diffraction pattern analysis

International Nuclear Information System (INIS)

Kral, M.V.; McIntyre, H.R.; Smillie, M.J.

2004-01-01

Intermetallic phases in sand cast eutectic Al-Si alloys were characterized using a combination of SEM, EDS and EBSD pattern analysis. Chinese script α-phase particles were consistent with cubic Al 19 (Fe,Mn) 5 Si 2 . Plate-shaped β-phase particles were consistent with tetragonal Al 3 (Fe,Mn)Si 2

High-temperature oxidation behavior of Ti3AlC2 in air

Institute of Scientific and Technical Information of China (English)

XU Xue-wen; LI Yang-xian; ZHU Jiao-qun; MEI Bing-chu

2006-01-01

Not only the isothermal oxidation behaviors at 900-1 300 ℃ for 20 h in air of bulk Ti3AlC2 with 2.8% TiC which was sintered by hot pressing with the additive of silicon,but also the cyclic oxidation behavior at 1 100-1 300 °C for 30 cycles,were investigated by using TG,XRD,SEM. The isothermal and cyclic oxidation behaviors generally follow a parabolic rate law. The parabolic rate constants of the former increased from 1.39×10-10 kg2/(m4·s) at 900 ℃ to 5.56×10-9 kg2/(m4·s) at 1 300 ℃. The calculated activation energy is 136.45 kJ/mol. The oxidation products are á-Al2O3 and little TiO2 at 900-1 000 ℃,however when the temperature is raised up to 1 200 ℃,TiO2 partially reacts to Al2TiO5,and the reaction is completed at 1 300 ℃. This demonstrates that Ti3AlC2 has excellent oxidation resistance and good thermal shock because the dense continuous oxide scale consists of mass á-Al2O3 and little TiO2 and/or Al2TiO5. Generally,the oxide scale is grown by the inward diffusion of O2- and the outward diffusion of Ti4+ and Al3+.

Interface analysis of A1 matrix composites produced by hot isostatic pressing, squeeze casting and semi-solid processing

International Nuclear Information System (INIS)

Shamsul, J.B.; Zainal Arifin Ahmad; Faaizulaswad, M.S.; Azmi, R.

2000-01-01

The interface analysis has been carried out an aluminium based composites system produced by hot isostatic pressing, squeeze casting and semi-solid processing. A range of different fabrication techniques has been used to produce different types of microstructure of Al 2124 (Al-Cu-Mg) reinforced with 5 weight % SiC particles. Blending followed by hot isostatic pressing is used to fabricate composite I. Composite II was 6061 (Al-Si-Mg) wrought aluminium alloy reinforced with fibres of alumina-silica (V f = 0.58) and fabricated by squeeze casting. Finally, A356 (AlSi7Mg0.3) alloy was reinforced with 20 Vol.% of SiC particles (13 μm) and namely as composite III. Composite III is fabricated by semi-solid processing. Interface analysis was done by optical microscopy, scanning and transmission electron microscopy. Composite I exhibited good interface bonding and dislocation was also observed near the interface. Elements such as Al, Fe, Cr, Mn were found near the interface of composite II and intermetallic of iron rich inclusion and Mg 2 Si were observed near the interface of composite III. (Author)

Microstructural characterization of silicon added titanium aluminide

International Nuclear Information System (INIS)

Khan, A.N.

2009-01-01

Titanium aluminides intermetallic compounds have received great attention during the past decade, since they have the potential, in aircraft and automotive engines, to replace the high density Ni-base superalloys However, these intermetallics possess poor oxidation properties at high temperatures. Previous studies showed that protective alumina scale formation on gamma-TiAl can be obtained by small additions (around 2 at.%) of Ag. In the present study, a number of cast Ti-Al-Si alloys were investigated in relation to transient oxide formation in air at 1300 deg. C. After various oxidation times the oxide composition, microstructure and morphology were studied by combining a number of analysis techniques. The TiAl-Si alloys appear to form Al Ti and Si oxides. However, the formation of silicon oxide at the interface of base metal and scale slows down the oxidation rate significantly. (author)

Fabrication of Ti-0.48Al Alloy by Centrifugal Casting.

Science.gov (United States)

Park, Jong Bum; Lee, Jung-Il; Ryu, Jeong Ho

2018-09-01

Many of the unique properties of TiAl alloys that make are attractive for use in high-temperature structural applications also make it challenging to process them into useful products. Cast TiAl is rapidly nearing commercialization, particularly in the vehicle industry, owing to its low production cost. In this study, the centrifugal casting of a TiAl (Ti-48%Al, mole fraction) turbocharger was simulated and an experimental casting was created in vacuum using an induction melting furnace coupled to a ceramic composite mold. Numerical simulation results agreed with the experiment. The crystal structure, microstructure, and chemical composition of the TiAl prepared by centrifugal casting were studied by X-ray diffractometry, optical microscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). FE-SEM and EDS examinations of the TiAl casting revealed that the thickness of the oxide layer (α-case) was typically less than 35 μm.

The relation between wetting and infiltration behaviour in the Al-1010/TiC and Al-2024/TiC Systems

International Nuclear Information System (INIS)

Contreras, A.; Lopez, V.H.; Leon, C.A.; Bedolla, E.; Drew, R.A.A.

2001-01-01

Wetting and infiltration behavior of TiC by commercial aluminum (Al-1010) and Al-2024 alloy was investigated. Wettability tests were performed on dense TiC substrates (96.8% theoretical density) using a sessile drop technique in the temperature range of 850 to 1000 deg C under vacuum atmosphere. Pressureless melt infiltration of particulate TiC performs (56% theoretical density) was carried out under an inert atmosphere at temperatures ranging from 900 to 1100 deg C. Infiltration profiles were obtained using a thermogravimetric analyzer (TGA), which measured continuously the weight change of the compacts as the liquid alloy infiltrated From the wetting study, it was found that wettability of TiC by liquid Al-1010 was better than Al-2024. A strong temperature dependence was observed. Electron probe microanalysis (EPMA) indicated that aluminum carbide (Al 4 C 3 ) is formed at the interface in both metal/ceramic assemblies. In agreement with the wetting results. Al-1010 exhibited the highest infiltration rate during composite fabrication. The activation energy determined from the slopes of Arrhenius plots for the infiltration rate at the different temperatures was 172 kJ/mol and 179 kJ/mol for the Al-1010/TiC and Al-2024/TiC systems, respectively. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

Effect of iron content on the structure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25} and (AlTi){sub 60-x}Ni{sub 20}Cu{sub 20}Fe{sub x} (x=15, 20) high-entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Fazakas, É., E-mail: eva.fazakas@bayzoltan.hu [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Wigner Research Center for Physics, Hungarian Academy of Sciences, H-1525, P.O.B. 49 (Hungary); Bay Zoltán Nonprofit Ltd., For Applied Research H-1116 Budapest, Fehérvári út 130 (Hungary); Zadorozhnyy, V. [National University of Science and Technology «MISIS», Leninsky prosp., 4, Moscow 119049 (Russian Federation); Louzguine-Luzgin, D.V. [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2015-12-15

Highlights: • Three new refractory alloys namely: Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20}, were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}C{sub u25} Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys are relatively hard and ductile. Being heat treated at 973 K the Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

Effect of molybdenum and chromium additions on the mechanical properties of Fe3Al-based alloys

International Nuclear Information System (INIS)

Sun Yangshan; Xue Feng; Mei Jianping; Yu Xingquan; Zhang Lining

1995-01-01

Iron aluminides based on Fe 3 Al offer excellent oxidation and sulfidation resistance, with lower material cost and density than stainless steels. However, their potential use as structural material has been hindered by limited ductility and a sharp drop in strength above 600 C. Recent development efforts have indicated that adequate engineering ductility of 10--20% and tensile yield strength of as high as 500 MPa can be achieved through control of composition and microstructure. These improved tensile properties make Fe 3 Al-based alloys more competitive against conventional austenic and ferritic steels. The improvement of high temperature mechanical properties has been achieved mainly by alloying processes. Molybdenum has been found to be one of the most important alloying elements for strengthening Fe 3 Al-based alloys at high temperatures. However, the RT(room temperature) ductility decreases with the increase of a molybdenum addition. On the other hand, a chromium addition to Fe 3 Al-based alloys is very efficient for improving RT ductility but not beneficial to yield strength at temperatures to 800 C. The purpose of the present paper is to report the effects of combined additions of molybdenum and chromium on mechanical properties at ambient temperature and high temperature of 600 C

Utilisation of mould temperature change in eliminating the Al5FeSi phases in secondary AlSi7Mg0.3 alloy

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2017-03-01

Full Text Available This article describes the impact of the metal mould temperature change in eliminating the adverse effect of iron in the AlSi7Mg0.3 alloy. The kind of phases based on iron to be formed in aluminium alloys is determined by the alloy chemical composition, the melt overheating temperature prior to casting, and the cooling rate during crystallisation. In the experiment, we used three various mould temperatures, and their impact on the possible change in the adverse Al5FeSi phase, excreted in a needle form to a more compact form of Chinese writing or skeleton units. The experimental part did not use melt overheat that would result in impairment of the melt, for example due to increased gassing of the melt, as well as in a greater load on the smelting unit, thus resulting in increased energy expenditure. We can conclude from the obtained results that the mould temperature change does not have an adequate effect in eliminating the adverse effect of iron in Al-Si-Mg alloys.

Effect of the addition of Al-Ti-C master alloy on the microstructure and microhardness of a cast Al-10Mg alloy

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The microstructure and microhardness of a cast Al-10wt%Mg (henceforth Al-l0Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition.It was found that this level of the master alloy addition not only caused an effective grain refinement, but also caused a significant increase in the microhardness of the Al-10Mg alloy.Microchemical analysis revealed that TiC particles existed in the grain center.The relationship between the holding time and grain size was also studied.It shows that the grain refining efficiency is faded observably with the holding time.This is explained in terms of the instability of TiC particles.

High temperature mechanical properties of iron aluminides

International Nuclear Information System (INIS)

Morris, D. G.; Munoz-Morris, M. A.

2001-01-01

Considerable attention has been given to the iron aluminide family of intermetallics over the past years since they offer considerable potential as engineering materials for intermediate to high temperature applications, particularly in cases where extreme oxidation or corrosion resistance is required. Despite efforts at alloy development, however, high temperature strength remains low and creep resistance poor. Reasons for the poor high-temperature strength of iron aluminides will be discussed, based on the ordered crystal structure, the dislocation structure found in the materials, and the mechanisms of dislocation pinning operating. Alternative ways of improving high temperature strength by microstructural modification and the inclusion of second phase particles will also be considered. (Author)

Fabrication, interfacial characterization and mechanical properties of continuous Al{sub 2}O{sub 3} ceramic fiber reinforced Ti/Al{sub 3}Ti metal-intermetallic laminated (CCFR-MIL) composite

Energy Technology Data Exchange (ETDEWEB)

Han, Yuqiang; Lin, Chunfa; Han, Xiaoxiao; Chang, Yunpeng; Guo, Chunhuan, E-mail: guochunhuan@hrbeu.edu.cn; Jiang, Fengchun, E-mail: fengchunjiang@hrbeu.edu.cn

2017-03-14

Continuous Al{sub 2}O{sub 3} ceramic fiber reinforced Ti/Al{sub 3}Ti metal-intermetallic laminated (CCFR-MIL) composite was fabricated using a vacuum hot pressing (VHP) sintering method and followed by hot isostatic pressing (HIP). The microstructure characteristics of the interfaces between Ti and Al{sub 3}Ti, as well as Al{sub 2}O{sub 3} fiber and Al{sub 3}Ti intermetallic were analyzed by scanning electron microscopy (SEM). Elemental distribution in the interfacial reaction zones were quantitatively examined by energy-dispersive spectroscopy (EDS). The phases in the composite were identified by X-ray diffractometer (XRD). The mechanical properties of the CCFR-MIL composite were measured using compression and tensile tests under quasi-static strain rate. The experimental results indicated that the residual Al was found in Al{sub 3}Ti intermetallic layer of CCFR-MIL composite. The interfacial reactions occurred during HIP and the reaction products were determined to be Al{sub 2}Ti, TiSi{sub 2}, TiO{sub 2} and Al{sub 2}SiO{sub 5} phases. Compared to Ti/Al{sub 3}Ti MIL composite without fiber reinforcement, both the strength and failure strain of CCFR-MIL composite under both compressive and tensile stress states increased due to the contribution of the continuous ceramic Al{sub 2}O{sub 3} fiber.

Corrosion performance of iron aluminides in fossil energy environments

Energy Technology Data Exchange (ETDEWEB)

Natesan, K. [Argonne National Lab., IL (United States). Energy Technology Div.

1997-12-01

Corrosion of metallic structural materials in complex gas environments of coal gasification and combustion is a potential problem. The corrosion process is dictated by concentrations of two key constituents: sulfur as H{sub 2}S or SO{sub 2} and chlorine as HCl. This paper presents a comprehensive review of the current status of the corrosion performance of alumina scales that are thermally grown on Fe-base alloys, including iron aluminides, in multicomponent gas environments of typical coal-conversion systems. Mechanisms of scale development/breakdown, performance envelopes for long-term usage of these materials, approaches to modifying the surfaces of engineering alloys by cladding or coating them with intermetallics, and in-service experience with these materials are emphasized. The results are compared with the performance of chromia-forming alloys in similar environments. The paper also discusses the available information on corrosion performance of alloys whose surfaces were enriched with Al by the electrospark deposition process or by weld overlay techniques.

Influence of additives on the microstructure and tensile properties of near-eutectic Al-10.8%Si cast alloy

International Nuclear Information System (INIS)

Mohamed, A.M.A.; Samuel, A.M.; Samuel, F.H.; Doty, H.W.

2009-01-01

The continuing quest for aluminum castings with enhanced mechanical properties for applications in the automotive industries has intensified the interest in aluminum-silicon alloys. In Al-Si alloys, the properties are influenced by the shape and distribution of the eutectic silicon particles in the matrix, as also by the iron intermetallics and copper phases that occur upon solidification. The detailed microstructure and tensile properties of as-cast and heat-treated new experimental alloy belonging to cast Al-Si near-eutectic alloys have been investigated as a function of Fe, Mn, Cu, and Mg content. Microstructural examination was carried out using optical microscopy, image analysis, and electron probe microanalysis (EPMA), wavelength dispersive spectroscopic (WDS) analysis facilities. Tensile properties upon artificial aging in the temperature range of 155-240 o C for 5 h were also investigated. The results show that the volume fraction of Fe-intermetallics increases as the iron or manganese contents increase. Compact polygonal or star-like particles form when the sludge factor is greater than 2.1. The Al 2 Cu phase was observed to dissolve almost completely during solution heat treatment of all the alloys studied, especially those containing high levels of Mg and Fe, while Al 5 Cu 2 Mg 8 Si 6 , sludge, and α-Fe phases were found to persist after solution heat treatment. The β-Al 5 (Fe,Mn)Si phase dissolved partially in Sr-modified alloys, and its dissolution became more pronounced after solution heat treatment. At 0.5% Mn, the β-Fe phase forms when the Fe content is above 0.75%, causing the tensile properties to decrease drastically. The same results are obtained when the levels of both Fe and Mn are increased beyond 0.75%, because of sludge formation. On the other hand, the tensile properties of the Cu-containing alloys are affected slightly at high levels of Mg as a result of the formation of Al 5 Cu 2 Mg 8 Si 6 which decreases the amount of free Mg

Sapphire/TiAl composites - structure and properties

International Nuclear Information System (INIS)

Povarova, K.B.; Antonova, A.V.; Mileiko, S.T.; Sarkissyan, N.S.

2001-01-01

Ti-Al-intermetallic-based alloys with lamellar microstructure, -γ(TiAl) +α 2 (Ti 3 Al) are characterized by a high melting point of 1460 o C, a low density of ∼3.9 g/cm 3 , a high gas corrosion resistance up to a temperature of about 900 o C, a high creep resistance up to a temperature of about 800 o C, and a sufficiently high fracture toughness at low temperatures, up to 30 Mpa x m 1/2 . Hence, they are considered as excellent matrices for fibres of high melting point. Unlike well-developed SiC/TiAl composites, which have an obvious upper limit for the usage temperature due to SiC/TiAl interaction, Sapphire/TiAl composites remain nearly unknown because fibres to be used in such composites have not been really available. At the present time, such fibres are developed in Solid State Physics Inst. of RAS. The results of preliminary creep tests of Al 2 O 3 /TiAl composites obtained by using pressure casting have shown that usage of such composite systems shifts the temperature limit for light structural materials in terms of creep resistance to, at least, 1050 o C: creep strength on 100 h time base reaches 120 MPa at that temperature. It occurs also that Sapphire-fibres/TiAl-matrix composite specimens have an increased gas corrosion resistance by more than one order of the magnitudes as compared with that of the matrix alloy. (author)

Microstructure and mechanical properties of TiAl castings produced by zirconia ceramic mould

Directory of Open Access Journals (Sweden)

Tian Jing

2011-11-01

Full Text Available Owing to their low density and attractive high-temperature properties, gamma titanium aluminide alloys (TiAl alloys, hereafter have significant potential application in the aerospace and automobile industries, in which these materials may replace the heavier nickel-based superalloys at service temperatures of 600 – 900℃. Investment casting of TiAl alloys has become the most promising cost-effective technique for the manufacturing of TiAl components. Ceramic moulds are fundamental to fabricating the TiAl casting components. In the present work, ceramic mould with a zirconia primary coat was designed and fabricated successfully. Investment casting of TiAl blades and tensile test of specimens was carried out to verify the correctness and feasibility of the proposed method. The tensile test results indicate that, at room temperature, the tensile strength and the elongation are about 450 MPa and 0.8%, respectively. At 700℃, the tensile strength decreases to about 410 MPa and the elongation increases to 2.7%. Microstructure and mechanical properties of investment cast TiAl alloy are discussed.

First-principles calculations of Ti{sub 3}SiC{sub 2} and Ti{sub 3}AlC{sub 2} with hydrogen interstitial

Energy Technology Data Exchange (ETDEWEB)

Xu, Canhui [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900 (China); Zhang, Haibin, E-mail: hbzhang@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900 (China); Hu, Shuanglin; Zhou, Xiaosong; Peng, Shuming [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900 (China); Xiao, Haiyan [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Zhang, Guojun [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Research Institute of Functional Materials, Donghua University, Shanghai, 201620 (China)

2017-05-15

In this paper, the effects of hydrogen interstitial defect on the structural stability of two kinds of MAX materials (Ti{sub 3}SiC{sub 2} and Ti{sub 3}AlC{sub 2}) were investigated by first-principles calculations. The results indicated that the hydrogen interstitial energetically prefers to reside at the 2Ti3Si site for Ti{sub 3}SiC{sub 2} and 3TiAl site for Ti{sub 3}AlC{sub 2}, respectively, and the latter has much lower formation energy. Both of these MAX phases are slightly hardened and the elastic anisotropy is reduced appreciably after the introduction of hydrogen interstitial. The hydrogen interstitial in Ti{sub 3}SiC{sub 2} and Ti{sub 3}AlC{sub 2} leads to an electronic localization effect on the Si/Al atom and the effect is more remarkable in Ti{sub 3}AlC{sub 2}. The interlayer bonding strength of Ti{sub 3}AlC{sub 2} is more weakened by hydrogen interstitials than that of Ti{sub 3}SiC{sub 2}. As a result, the interatomic bonding between Si/Al and Ti atom layers is deteriorated and their structural stabilities degrade subsequently.

Ni.sub.3 Al-based intermetallic alloys having improved strength above 850.degree. C.

Science.gov (United States)

Liu, Chain T.

2000-01-01

Intermetallic alloys composed essentially of: 15.5% to 17.0% Al, 3.5% to 5.5% Mo, 4% to 8% Cr, 0.04% to 0.2% Zr, 0.04% to 1.5% B, balance Ni, are characterized by melting points above 1200.degree. C. and superior strengths at temperatures above 1000.degree. C.

Effects of Ti and TiC ceramic powder on laser-cladded Ti-6Al-4V in situ intermetallic composite

Science.gov (United States)

Ochonogor, O. F.; Meacock, C.; Abdulwahab, M.; Pityana, S.; Popoola, A. P. I.

2012-12-01

Titanium metal matrix composite (MMCs) was developed on titanium alloy (Ti-6Al-4V) substrate with the aim of improving the hardness and wear properties by laser cladding technique using a Rofin Sinar 4 kW Nd: YAG laser. Wear investigations were carried out with the aid of three body abrasion tester. The resultant microstructure show homogeneous distribution of TiC particles free from cracks and pores. Multiple track deposited systems with 50% overlap revealed micro-hardness increase from 357.3 HV0.1for the substrate reaching a peak as high as 922.2 HV0.1 for 60%Ti + 40%TiC and the least 665.3 HV0.1 for 80%Ti + 20%TiC MMCs. The wear resistance of the materials improved significantly, indicating a fifteen-fold wear rate reduction due to the proper distribution of ceramic particles thereby forming interstitial carbides as revealed by the X-ray diffraction spectrum.

Mechanical Properties of SiC, Al2O3 Reinforced Aluminium 6061-T6 Hybrid Matrix Composite

Science.gov (United States)

Murugan, S. Senthil; Jegan, V.; Velmurugan, M.

2018-04-01

This paper contains the investigation of tensile, compression and impact characterization of SiC, Al2O3 reinforced Aluminium 6061-T6 matrix hybrid composite. Hybrid matrix composite fabrication was done by stir casting method. An attempt has been made by keeping Al2O3 percentage (7%) constant and increasing SiC percentage (10, 15, and 20%). After fabricating, the samples were prepared and tested to find out the various mechanical properties like tensile, compressive, and impact strength of the developed composites of different weight % of silicon carbide and Alumina in Aluminium alloy. The main objective of the study is to compare the values obtained and choose the best composition of the hybrid matrix composite from the mechanical properties point of view.

Microstructural characterization and compression properties of TiC{sub 0.61}/Cu(Al) composite synthesized from Cu and Ti{sub 3}AlC{sub 2} powders

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhenying, E-mail: zhyhuang@bjtu.edu.cn [Institute of Material Science and Engineering, School of Mechanical and Electronic Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Institut PPRIME, Département de Physique et Mécanique des Matériaux, CNRS, Université de Poitiers, ENSMA, UPR 3346, SP2MI, Téléport 2 Boulevard Marie et Pierre Curie, BP 30179, F86962 Futuroscope Chasseneuil Cedex (France); Bonneville, Joel [Institut PPRIME, Département de Physique et Mécanique des Matériaux, CNRS, Université de Poitiers, ENSMA, UPR 3346, SP2MI, Téléport 2 Boulevard Marie et Pierre Curie, BP 30179, F86962 Futuroscope Chasseneuil Cedex (France); Zhai, Hongxiang [Institute of Material Science and Engineering, School of Mechanical and Electronic Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Gauthier-Brunet, Veronique [Institut PPRIME, Département de Physique et Mécanique des Matériaux, CNRS, Université de Poitiers, ENSMA, UPR 3346, SP2MI, Téléport 2 Boulevard Marie et Pierre Curie, BP 30179, F86962 Futuroscope Chasseneuil Cedex (France); and others

2014-07-25

Highlights: • Submicro-layered TiC{sub 0.61}/Cu(Al) nanocomposite. • MAX phase. • High yield stress. • Deformation mechanism. - Abstract: A new submicro-layered TiC{sub 0.61}/Cu(Al) composite has been prepared by hot-pressing a mixture of 50 vol.% Ti{sub 3}AlC{sub 2} and 50 vol.% Cu powders at 1150 °C and 30 MPa. It is shown that the initial reinforcement Ti{sub 3}AlC{sub 2} particles have, after synthesis, an unusual microstructure, which consists of submicron-thick layers of TiC{sub 0.61} and Cu(Al) alloy. Both the width of the TiC{sub 0.61} and Cu(Al) layers are ∼150 nm. Thus, the Ti{sub 3}AlC{sub 2} particles are decomposed into the TiC{sub 0.61} phase, while the additional Al atoms provided by Ti{sub 3}AlC{sub 2} diffuse into the molten Cu matrix at high temperature. Compression tests were performed at constant strain rate in the temperature range 20–800 °C. The new designed TiC{sub 0.61}/Cu(Al) composite has both a high yield stress, σ{sub 0.2} measured at 0.2% strain offset, and a high ultimate compressive strength, σ{sub UCS}, which is attributed to strong interface bonding between TiC{sub 0.61} and Cu(Al) phase. For instance, at 20 and 200 °C, σ{sub 0.2} is 770 MPa and 700 MPa, while σ{sub UCS} is 1.18 GPa and 1 GPa, respectively. Plastic deformation takes place in the Cu(Al) matrix. Wavy slip lines are observed indicating that cross-slip could be the dominant deformation mechanism.

Thin wall ductile iron casting as a substitute for aluminum alloy casting in automotive industry

Directory of Open Access Journals (Sweden)

M. Górny

2009-01-01

Full Text Available In paper it is presented thin wall ductile iron casting (TWDI as a substitute of aluminium alloy casting. Upper control arm made of ductile iron with wall thickness ranging from 2 – 3.7 mm was produced by inmold process. Structure, mechanical properties and computer simulations were investigated. Structural analysis of TWDI shows pearlitic-ferritic matrix free from chills and porosity. Mechanical testing disclose superior ultimate tensile strength (Rm, yield strength (Rp0,2 and slightly lower elongation (E of TWDI in comparison with forged control arm made of aluminium alloy (6061-T6. Moreover results of computer simulation of static loading for tested control arms are presented. Analysis show that the light-weight ductile iron casting can be loaded to similar working conditions as the forged Al alloy without any potential failures.

Effect of ageing time 200 °C on microstructure behaviour of Al-Zn-Cu-Mg cast alloys

Directory of Open Access Journals (Sweden)

Pratiwi Diah Kusuma

2017-01-01

Full Text Available Al-Zn-Cu-Mg is heat treatable alloy that can be used in many hightech applications, such as aerospace and military. The main objective of this study is to investigate the influence of ageing process in microstrucure behaviour of Al-9Zn-5Cu-4Mg cast alloy by performing SEM analysis and its correlation with hardness tests of as-cast Al-9Zn-5Cu-4Mg alloy and heat treated Al-9Zn-5Cu-4Mg cast alloy. The results show the deployment of precipitation spread over the dendrite and also the presence of second phases Mg3Zn3Al2 , Cu2FeAl7 , CuAl2, and CuMgAl2 in as-cast Al-9Zn-5Cu-4Mg alloy. The presence of all these second phases are affecting to the toughness of aluminium alloy and the presence of MgZn2 leads the impairment of hardness value of heat-treated Al-9Zn-5Cu-5Mg cast alloy.

Oxidation behavior of Al/Cr coating on Ti2AlNb alloy at 900 °C

Science.gov (United States)

Yang, Zhengang; Liang, Wenping; Miao, Qiang; Chen, Bowen; Ding, Zheng; Roy, Nipon

2018-04-01

In this paper, the Al/Cr coating was fabricated on the surface of Ti2AlNb alloy via rf magnetron sputtering and double glow treatment to enhance oxidation resistance. The protective coating with an outer layer of Al and inner layer of Cr has great bonding strength due to the in-diffusion of Cr and the inter-diffusion between Al and Cr to form Al-Cr alloyed layer which has great hardness. Acoustic emission curve which was detected via WS-2005 scratch tester indicates the bonding strength between Al/Cr coating and substrate is great. Morphology of Ti2AlNb alloy with Al/Cr coating after scratch test shows that the scratch is smooth without disbanding, and the depth and breadth of scratch are changed uniformly. The mass change was reduced after oxidation test due to the Al/Cr protective coating. Isothermal oxidation test at 900 °C was researched. Results indicate that Al/Cr coating provided oxidation resistance of Ti2AlNb alloy with prolonged air exposure at 900 °C. Al2O3 was detected by XRD patterns and SEM images, and was formed on the surface of Ti2AlNb alloy to protect substrate during oxidation test. A certain content of Cr is beneficial for the formation of Al2O3. Besides, Cr2O3 was produced under Al2O3 by outward diffusion of Cr to protect substrate sequentially, no cracks were discovered on Al/Cr protective coating. The process of Ti outward diffusion into surface was suppressive due to integration of Cr-Ti and Al-Ti intermetallics. A steady, adherent and continuous coated layer of Al/Cr on Ti2AlNb alloy increases oxidation resistance.

High-Pressure Spark Plasma Sintering (HP SPS): A Promising and Reliable Method for Preparing Ti-Al-Si Alloys.

Science.gov (United States)

Knaislová, Anna; Novák, Pavel; Cygan, Sławomir; Jaworska, Lucyna; Cabibbo, Marcello

2017-04-27

Ti-Al-Si alloys are prospective material for high-temperature applications. Due to low density, good mechanical properties, and oxidation resistance, these intermetallic alloys can be used in the aerospace and automobile industries. Ti-Al-Si alloys were prepared by powder metallurgy using reactive sintering, milling, and spark plasma sintering. One of the novel SPS techniques is high-pressure spark plasma sintering (HP SPS), which was tested in this work and applied to a Ti-10Al-20Si intermetallic alloy using a pressure of 6 GPa and temperatures ranging from 1318 K (1045 °C) to 1597 K (1324 °C). The low-porosity consolidated samples consist of Ti₅Si₃ silicides in an aluminide (TiAl) matrix. The hardness varied between 720 and 892 HV 5.

Ta4AlC3: Phase determination, polymorphism and deformation

International Nuclear Information System (INIS)

Eklund, P.; Palmquist, J.-P.; Hoewing, J.; Trinh, D.H.; El-Raghy, T.; Hoegberg, H.; Hultman, L.

2007-01-01

Ta 4 AlC 3 , a new member of the M n+1 AX n -phase family, has been synthesized and characterized (n = 1-3; M = early transition metal; A A-group element; and X = C and/or N). Phase determination by Rietveld refinement of synchrotron X-ray diffraction data shows that Ta 4 AlC 3 belongs to the P6 3 /mmc space group with a and c lattice parameters of 3.10884 ± 0.00004 A and 24.0776 ± 0.0004 A, respectively. This is shown to be the α-polymorph of Ta 4 AlC 3 , with the same structure as Ti 4 AlN 3 . Lattice imaging by high-resolution transmission electron microscopy demonstrates the characteristic MAX-phase stacking of α-Ta 4 AlC 3 . Three modes of mechanical deformation of α-Ta 4 AlC 3 are observed: lattice bending, kinking and delamination

Study of an Al-Si-Cu HPDC alloy with high Zn content for the production of components requiring high ductility and tensile properties

Energy Technology Data Exchange (ETDEWEB)

Vicario, Iban; Egizabal, Pedro; Galarraga, Haize; Plaza, Luis Maria; Crespo, Inigo [Fundacion Tecnalia Research and Innovation, Donostia-San Sebastien (Spain). Dept. of foundry processes

2013-04-15

Conventional high-pressure die casting aluminium components present certain limitations in terms of mechanical properties attainable due to the intrinsic porosity of the castings as well as the presence of iron-based brittle intermetallic phases. The present work approaches the increase in ductility and tensile strength through the analysis of the effect of the alloying elements of AlSi alloys used for high-pressure die casting. The combination of alloying elements providing the best results in terms of ductility and tensile strength were eventually selected to produce a batch of components that were thoroughly tested. The final alloy had a composition of Si 8.21, Fe 0.78, Cu 1.53, Mn 0.64, Mg 0.46, Ni 0.07, Zn 3.37, Pb 0.34, Sn 0.27, Ti 0.18 and Cr 0.04wt.%. The selected alloy performance was compared to that of the commercial AlSi9Cu3 and Silafont {sup registered} 36 alloys.

Microstructural stability of heat-resistant high-pressure die-cast Mg-4Al-4Ce alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei; Zhang, Jinghuai; Li, Guoqiang; Feng, Yan; Su, Minliang; Wu, Ruizhi; Zhang, Zhongwu [Harbin Engineering Univ. (China). Key Laboratory of Superlight Material and Surface Technology; Jiao, Yufeng [Jiamusi Univ. (China). College of Materials Science and Engineering

2017-05-15

The thermal stability of Al-RE (rare earth) intermetallic phases with individual RE for heat-resistant high-pressure die-casting Mg-Al-RE alloys is investigated. The results of this study show that the main strengthening phase of Mg-4Al-4Ce alloy is Al{sub 11}Ce{sub 3}, whose content is about 5 wt.% according to quantitative X-ray diffraction phase analysis. The Al{sub 11}Ce{sub 3} phase appears to have high thermal stability at 200 C and 300 C, while phase morphology change with no phase structure transition could occur for Al{sub 11}Ce{sub 3} when the temperature reaches 400 C. Furthermore, besides the kinds of rare earths and temperature, stress is also an influencing factor in the microstructural stability of Mg-4Al-4Ce alloy.

Effects of Processing Parameters on the Fabrication of in-situ Al/TiC Composites by Thermally Activated Combustion Reaction Process in an Aluminium Melt using Al-TiO_2-C Powder Mixtures

International Nuclear Information System (INIS)

Kim, Hwa-Jung; Lee, Jung-Moo; Cho, Young-Hee; Kim, Jong-Jin; Kim, Su-Hyeon; Lee, Jae-Chul

2012-01-01

A feasible way to fabricate in-situ Al/TiC composites was investigated. An elemental mixture of Al-TiO_2-C pellet was directly added into an Al melt at 800-920°C to form TiC by self-combustion reaction. The addition of CuO initiates the self-combustion reaction to form TiC in 1-2 um at the melt temperature above 850°C. Besides the CuO addition, a diluent element of excess Al plays a significant role in the TiC formation by forming a precursor phase, Al_3Ti. Processing parameters such as CuO content, the amount of excess Al and the melt temperature, have affected the combustion reaction and formation of TiC, and their influences on the microstructures of in-situ Al/TiC composites are examined.

Covalent bonding and band-gap formation in ternary transition-metal di-aluminides: Al4MnCo and related compounds

International Nuclear Information System (INIS)

Krajci, M.; Hafner, J.

2002-01-01

In this paper we extend our previous study of the electronic structure of and bonding mechanism in transition-metal (TM) di-aluminides to ternary systems. We have studied the character of the bonding in Al 4 MnCo and related TM di-aluminides in the C11 b (MoSi 2 ) and C54 (TiSi 2 ) crystal structures. A peculiar feature of the electronic structure of these TM di-aluminides is the existence of a semiconducting gap at the Fermi level. In our previous work we predicted a gap in Al 2 TM compounds where the TM atoms have eight valence electrons. Here we demonstrate that the semiconducting gap does not disappear if the TM sites are occupied by two different TMs, provided that the electron-per-atom ratio is conserved. Such a replacement substantially increases the class of possibly semiconducting TM di-aluminides. Substitution for 3d TMs of 4d or 5d TMs enhances the width of the gap. From the analysis of the charge density distribution and the crystal orbital overlap population, we conclude that the bonding between atoms has dominantly covalent character. This is confirmed not only by the enhanced charge density halfway between atoms, but also by the clear bonding-antibonding splitting of the electronic states. If the gaps between split states that correspond to all bonding configurations in the crystal have a common overlap at the Fermi level, the intermetallic compound becomes a semiconductor. However, the results of the total-energy calculations suggest that the existence of a band gap does not necessarily imply a stable structure. Strong covalent bonds can exist also in Al-TM structures where no band gap is observed. (author)

Electrical and magnetic behavior of iron doped nickel titanate (Fe{sup 3+}/NiTiO{sub 3}) magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lenin, Nayagam; Karthik, Arumugam; Sridharpanday, Mathu; Selvam, Mohanraj; Srither, Saturappan Ravisekaran; Arunmetha, Sundarmoorthy; Paramasivam, Palanisamy; Rajendran, Venkatachalam, E-mail: veerajendran@gmail.com

2016-01-01

Iron doped nickel titanate (Fe{sup 3+}/NiTiO{sub 3}) ferromagnetic nanoparticles with different concentrations of Fe (0.2, 0.4, and 0.6 mol) were synthesized using precipitation route with precursor source such as nickel nitrate and iron nitrate solutions. The prepared magnetic nanopowders were investigated through X-ray diffraction (XRD), Fourier transform infrared, scanning electron microscope, X-ray fluorescence, Brunauer–Emmett–Teller, vibrating sample magnetometer, and electrochemical impedance spectroscopy to explore the structural, ferromagnetic, and dielectric properties. The obtained XRD pattern shows formation of iron doped nickel titanate in orthorhombic structure. The crystallite size ranges from 57 to 21 nm and specific surface area ranges from 11 to 137 m{sup 2} g{sup −1}. The hysteresis loops of nanomagnetic materials show ferromagnetic behavior with higher magnitude of coercivity (H{sub c}) 867–462 Oe. The impedance analysis of ferromagnetic materials explores the ferro-dielectric behavior with enhanced properties of Fe{sup 3+}/NiTiO{sub 3} nanoparticles at higher Fe content. - Highlights: • Iron doped nickel titanate magnetic nanoparticles. • Ferromagnetic magnetism behavior with higher magnitude of coercivity. • Dielectric behavior of ferromagnetic nanoparticles with increase of Fe content.

Influence of electric current on microstructure evolution in Ti/Al and Ti/TiAl{sub 3} during spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Sun, Y. [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Haley, J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 (United States); Kulkarni, K. [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, UP (India); Aindow, M. [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Lavernia, E.J., E-mail: lavernia@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States)

2015-11-05

The synthesis of γ-TiAl from elemental metals via solid-state reactive diffusion processing routes involves multiple reaction steps with the formation of various intermediate intermetallic compounds, starting with TiAl{sub 3} because this phase is favored kinetically. To understand the processes by which the TiAl{sub 3} intermediate is eliminated during synthesis of γ-TiAl alloy via spark plasma sintering (SPS), the reaction between Ti and TiAl{sub 3} during SPS was studied with emphasis on the effects of the applied electric current and starting TiAl{sub 3} microstructure on the reaction kinetics and the underlying diffusion mechanisms. The intermediate intermetallic phases Ti{sub 3}Al, TiAl and TiAl{sub 2} were formed between the Ti and TiAl{sub 3} upon SPS processing at 900 °C. The applied electric current did not alter the character of the phases formation in the Ti/TiAl{sub 3} system, but thermodynamic calculations suggest that the activation energy for the nucleation of TiAl{sub 2} is reduced significantly with an electric current flowing. Moreover, the kinetics of the reactions between Ti and TiAl{sub 3} were enhanced when the starting TiAl{sub 3} microstructure was refined. The electric field also had a more significant influence on the grain growth kinetics for TiAl{sub 2} and TiAl in powder blend compacts with refined microstructures. - Highlights: • Reaction between Ti and TiAl{sub 3} during spark plasma sintering was studied. • Refined starting TiAl{sub 3} microstructure enhanced the reactions kinetics. • The nucleation barrier of TiAl{sub 2} was reduced by the applied electric field. • The applied electric field restrained the grain growth of TiAl and TiAl{sub 2}.

Synthesis, microstructure and mechanical properties of (Ti1−x,Nbx)2AlC/Al2O3 solid solution composites

International Nuclear Information System (INIS)

Zhu, Jianfeng; Han, Na; Wang, Anning

2012-01-01

(Ti,Nb) 2 AlC/Al 2 O 3 in-situ solid solution composites were successfully synthesized from the elemental powder mixtures of Nb 2 O 5 , Ti, Al and carbon black using hot-press-aided reaction synthesis. The reaction path was investigated by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), and a possible reaction mechanism was proposed to explain the formation of (Ti,Nb) 2 AlC/Al 2 O 3 composites in which the thermite reaction between Al and Nb 2 O 5 formed Al 2 O 3 and Nb, and the latter together with TiAl and TiC reacted to form (Ti,Nb) 2 AlC. The synthesized composites show plate-like grains packed in a laminated structure typical of Ti 2 AlC, and the fine Al 2 O 3 particles formed in-situ tend to disperse on the matrix grain boundaries. Compared with the monolithic Ti 2 AlC synthesized using an identical process, the Vickers hardness, maximum compressive stress, flexural strength and fracture toughness of (Ti 0.96 ,Nb 0.04 ) 2 AlC/5 wt% Al 2 O 3 were enhanced by 33.8%, 12.1%, 118.4% and 111.8%, respectively. The mechanisms by which Al 2 O 3 increases the strength and toughness of the material were also discussed.

Structural, morphological and interfacial characterization of Al-Mg/TiC composites

International Nuclear Information System (INIS)

Contreras, A.; Angeles-Chavez, C.; Flores, O.; Perez, R.

2007-01-01

Morphological and structural characterization of Al-Mg/TiC composites obtained by infiltration process and wetting by the sessile drop technique were studied. Focusing at the interface, wetting of TiC substrates by molten Al-Mg-alloys at 900 deg. C was investigated. Electron probe microanalysis (EPMA) indicated that aluminum carbide (Al 4 C 3 ) is formed at the interface and traces of TiAl 3 in the wetting assemblies were detected. Scanning Electron Microscopy (SEM) observations show that TiC particles do not appear to be uniformly attacked to produce a continuous layer of Al 4 C 3 at the interface. Molten Al-Mg-alloys were infiltrated into TiC preforms with flowing argon at a temperature of 900 deg. C. In the composites no reaction phase was observed by SEM. Quantification of the Al phase in the composite was carried out by X-ray diffraction (XRD) and Rietveld analysis. Chemical mapping analyzed by SEM shows that the Al-Mg alloy surrounds TiC particles. In the composites with 20 wt.% of Mg the Al-Mg-β phase was detected through XRD

Investigations on FCAM-III (Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3

Science.gov (United States)

Zöll, Klaus; Kahlenberg, Volker; Krüger, Hannes; Tropper, Peter

2018-02-01

In the course of a systematic study of a part of the quaternary system Fe2O3-CaO-Al2O3-MgO (FCAM) the previously unknown compound Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 (FCAM-III) has been synthesized. By analogy with the so-called SFCA series [1-5], our investigation in the system of FCAM shows the existence of a stoichiometric homologous series M14+6nO20+8n, where M = Fe, Ca, Al, Mg and n = 1 or 2. In air, we can prove the formation of coexisting FCAM-III and FCAM-I solid solutions at 1400 °C. By increasing the temperature up to 1425 °C FCAM-I disappears completely and FCAM-III co-exists with magnesiumferrite and a variety of calcium iron oxides. At 1450 °C FCAM-III breaks down to a mixture of FCAM-I again as well as magnesioferrite and melt. Small single-crystals of FCAM-III up to 35 μm in size could be retrieved from the 1425 °C experiment and were subsequently characterized using electron microprobe analysis and synchroton X-ray single-crystal diffraction. Finally the Fe2+/Fetot ratio was calculated from the total iron content based on the crystal-chemical formula obtained from EMPA measurements and charge balance considerations. FCAM-III or Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 has a triclinic crystal structure (space group P 1 ̅). The basic crystallographic data are: a = 10.223(22) Å, b = 10.316(21) Å, c = 14.203(15) Å, α = 93.473(50)°, β = 107.418(67)°, γ = 109.646(60)°, V = 1323.85(2) ų, Z = 1. Using Schreinemaker's technique to analyze the phase relations in the system Fe2O3-CaO-Al2O3-MgO it was possible to obtain the semi-quantitative stability relations between the participating phases and construct a topologically correct phase sequence as a function of T and fO2. The analysis shows that Ca2Al0.5Fe1.5O5 (C2A0.25F0.75) and CaAl1.5Fe2.5O7 (CA0.75F1.25) with higher calculated Fe2+ contents are preferably formed at lower oxygen fugacity and react to CaAl0.5Fe1.5O4 (CA0.25F0.75) by increasing fO2. Spinel-type magnesium-aluminium

Effect of Microstructure of Fe-C-V Alloys on Selected Functional Properties

Directory of Open Access Journals (Sweden)

Kawalec M.

2014-08-01

Full Text Available The cast alloys crystallizing in Fe-C-V system are classified as white cast iron, because all the carbon is bound in vanadium carbides. High vanadium cast iron has a very high abrasion resistance due to hard VC vanadium carbides. However, as opposed to ordinary white cast iron, this material can be treated using conventional machining tools. This article contains the results of the group of Fe-C-V alloys of various microstructure which are been tested metallographic, mechanical using an INSTRON machine and machinability with the method of drilling. The study shows that controlling the proper chemical composition can influence on the type and shape of the crystallized matrix and vanadium carbides. This makes it possible to obtain a high-vanadium cast iron with very high wear resistance while maintaining a good workability.

Studies on the sedimentation and agglomeration behavior of Al-Ti-B and Al-Ti-C grain refiners

Energy Technology Data Exchange (ETDEWEB)

Gazanion, F.; Chen, X.G.; Dupuis, C. [Alcan International Ltd., Jonquiere, PQ (Canada). Arvida Research and Development Centre

2002-07-01

The sedimentation and agglomeration behavior of Al-Ti-B and Al-Ti-C grain refiners in liquid aluminum has been investigated using the LiMCA and PoDFA analysis techniques in combination with metallographic examination. The widely used Al-5%Ti-1%B and Al-3%Ti-0.15%C master alloys were chosen. Two aluminum alloys, an AAlxxx (commercially pure metal) and an AA5182 (Al-4.5%Mg) alloy, were prepared with different additions of grain refiners. The difference in particle behavior in liquid aluminum for both refiners is described and briefly analyzed in terms of sensitivity to agglomeration and grain refiner performance. Experimental results indicate that, in comparison with the Al-Ti-B refiner, the Al-Ti-C refiner is detrimentally affected by long holding periods due to the decomposition of TiC particles within the melt. (orig.)

Design and syntheses of hybrid metal–organic materials based on K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] metallotectons

Energy Technology Data Exchange (ETDEWEB)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao, E-mail: dbwang@qust.edu.cn; Wang, Wenqiang; Wang, Lei, E-mail: inorchemwl@126.com

2016-05-15

By using K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] (C{sub 2}O{sub 4}{sup 2−}=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C_2O_4)_2(H_2O)_2}{sub 2}]·(H–L{sub 1}){sub 2}·H{sub 2}O 1, [Fe(C{sub 2}O{sub 4})Cl{sub 2}]·(H{sub 2}–L{sub 2}){sub 0.5}·(L{sub 2}){sub 0.5}·H{sub 2}O 2, [{Fe(C_2O_4)_1_._5Cl_2}{sub 2}]·(H–L{sub 3}){sub 4}3, [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]·(H{sub 2}–L{sub 4}){sub 2}·2H{sub 2}O 4, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H{sub 2}–L{sub 5})·2H{sub 2}O 5, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 6, K[Cr(C{sub 2}O{sub 4}){sub 3}]·2H{sub 2}O 7, Na[Fe(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 8 (with L{sub 1}=4-dimethylaminopyridine, L{sub 2}=2,3,5,6-tetramethylpyrazine, L{sub 3}=2-aminobenzimidazole, L{sub 4}=1,4-bis-(1H-imidazol-1-yl)benzene, L{sub 5}=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L{sub 6}=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O){sub 2}]{sup −} unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C{sub 2}O{sub 4})Cl{sub 2}]{sup -} anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe{sub 2}(C{sub 2}O{sub 4}){sub 3}Cl{sub 4}]{sup 4−} unit. Compound 4 features distinct [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]{sup 4−} units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C{sub 2}O{sub 4}){sub 3}]{sup 3−} units and K{sup +} cations. The 1D chains are further extended into 3D antionic H-bonded framework through O–H···O H-bonds. Compounds 6–8 show 2D [KAl(C{sub 2}O

Isothermal section of the Er-Fe-Al ternary system at 800 oC

International Nuclear Information System (INIS)

Jemmali, M.; Walha, S.; Pasturel, M.; Tougait, O.; Ben Hassen, R.; Noel, H.

2010-01-01

Physico-chemical analysis techniques, including X-ray diffraction and Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy, were employed to construct the isothermal section of the Er-Fe-Al system at 800 o C. At this temperature, the phase diagram is characterized by the formation of five intermediate phases, ErFe 12-x Al x with 5 ≤ x ≤ 8 (ThMn 12 -type), ErFe 1+x Al 1-x with -0.2 ≤ x ≤ 0.75 (MgZn 2 -type), ErFe 3-x Al x with 0.5 2 Al-type), Er 2 Fe 17-x Al x with 4.74 ≤ x ≤ 5.7 (TbCu 7 -type) and Er 2 Fe 17-x Al x with 5.7 2 Zn 17 -type), seven extensions of binaries into the ternary system; ErFe x Al 3-x with x 3 Cu-type), ErFe x Al 2-x with x ≤ 0.68 (MgCu 2 -type), Er 2 Fe x Al 1-x with x ≤ 0.25 (Co 2 Si-type), ErFe 2-x Al x with x ≤ 0.5 (MgCu 2 -type), ErFe 3-x Al x with x ≤ 0.5 (Be 3 Nb-type), Er 6 Fe 23-x Al x with x ≤ 8 (Th 6 Mn 23 -type), and Er 2 Fe 17-x Al x with x ≤ 4.75 (Th 2 Ni 17 -type) and one intermetallic compound; the ErFe 2 Al 10 (YbFe 2 Al 10 -type).

Influence wt.% of SiC and borax on the mechanical properties of AlSi-Mg-TiB-SiC composite by the method of semi solid stir casting

Science.gov (United States)

Bhiftime, E. I.; Guterres, Natalino F. D. S.; Haryono, M. B.; Sulardjaka, Nugroho, Sri

2017-04-01

SiC particle reinforced metal matrix composites (MMCs) with solid semi stir casting method is becoming popular in recent application (automotive, aerospace). Stirring the semi solid condition is proven to enhance the bond between matrix and reinforcement. The purpose of this study is to investigate the effect of the SiC wt.% and the addition of borax on mechanical properties of composite AlSi-Mg-TiB-SiC and AlSi-Mg-TiB-SiC/Borax. Specimens was tested focusing on the density, porosity, tensile test, impact test microstructure and SEM. AlSi is used as a matrix reinforced by SiC with percentage variations (10, 15, 20 wt.%). Giving wt.% Borax which is the ratio of 1: 4 between wt.% SiC. The addition of 1.5% of TiB gives grain refinement. The use of semi-solid stir casting method is able to increase the absorption of SiC particles into a matrix AlSi evenly. The improved composite presented here can be used as a guideline to make a new composite.

Studies on SiC(p) reinforced Al-Al sub 3 Ni eutectic matrix composites

International Nuclear Information System (INIS)

Masrom, A.K.; Foo, L.C.; Ismail, A.B.

1996-01-01

An investigation on processing of Al-5.69wt% Ni eutectic with SiC particulate composites is reported. The intermetallic composites are prepared by elemental powder metallurgy route and sintered at two different temperatures, i.e., 600 degree C and 620 degree C. Results show that the metal matrix was Al-Al sub 3 Ni eutectic. The phase analysis by XRD identified the presence of Al sub 3 Ni and Al as dominant phases together with silicon and Al sub 4 C sub 3 phase as minor phases. The Al sub 4 C sub 3 and Si phases are formed during sintering due to SiC-Al interface reaction. SEM micrographs also reveal the formation of microvoid surrounding the SiC particle

Iron aluminide knife and method thereof

Science.gov (United States)

Sikka, Vinod K.

1997-01-01

Fabricating an article of manufacture having a Fe.sub.3 Al-based alloy cutting edge. The fabrication comprises the steps of casting an Fe.sub.3 Al-based alloy, extruding into rectangular cross section, rolling into a sheet at 800.degree. C. for a period of time followed by rolling at 650.degree. C., cutting the rolled sheet into an article having an edge, and grinding the edge of the article to form a cutting edge.

Ordering and site occupancy of ternary elements in Fe{sub 3}Al

Energy Technology Data Exchange (ETDEWEB)

Rademacher, Thomas; Al-Kassab, Talaat; Kirchheim, Reiner [Institut fuer Materialphysik, Universitaet Goettingen (Germany)

2009-07-01

Ordered iron aluminides exhibit a number of advantageous properties, such as high-temperature strength, corrosion resistance and low cost. Therefore, iron aluminum based alloys are considered to replace in some cases high alloyed ferritic stainless steels, especially DO{sub 3} - ordered Fe{sub 3}Al. The mechanical properties and high-temperature stability can be optimized when ternary elements are added. In this study the site occupancy of ternary elements (4at.%V, 5at.%Cr, 5at.%Mn) has been investigated by means of Atom Probe Tomography (APT). A special analysis algorithm allows resolving the atom layers for different measurement directions which enables determining site preferences. Additionally, comparing the succession of layers with simulations the binding energies of the participating elements can be estimated.

Influence of copper content on microstructure development of AlSi9Cu3 alloy

Directory of Open Access Journals (Sweden)

Brodarac Zovko Z.

2014-01-01

Full Text Available Microstructure development and possible interaction of present elements have been determined in charge material of EN AlSi9Cu3 quality. Literature review enables prediction of solidification sequence. Modelling of equilibrium phase diagram for examined chemical composition has been performed, which enables determination of equilibrium solidification sequence. Microstructural investigation indicated distribution and morphology of particular phase. Metallographic analysis tools enable exact determination of microstructural constituents: matrix αAl, eutectic αAl+βSi, iron base intermetallic phase - Al5FeSi, Alx(Fe,MnyCuuSiw and/or Alx(Fe,MnyMgzCuuSiw and copper base phases in ternary eutectic morphology Al-Al2Cu-Si and in complex intermetallic ramified morphology Alx(Fe,MnyMgzSiuCuw. Microstructure development examination reveals potential differences due to copper content which is prerequisite for high values of final mechanical, physical and technological properties of cast products.

Parametric investigation of the formation of epitaxial Ti{sub 3}SiC{sub 2} on 4H-SiC from Al-Ti annealing

Energy Technology Data Exchange (ETDEWEB)

Abi-Tannous, T., E-mail: tony.abi-tannous@insa-lyon.fr [Université de Lyon, CNRS, Laboratoire Ampère, INSA-Lyon, UMR 5005, F-69621 (France); Soueidan, M. [Université de Lyon, CNRS, Laboratoire Ampère, INSA-Lyon, UMR 5005, F-69621 (France); Ferro, G. [Université de Lyon, CNRS, Laboratoire des Multimatériaux et Interfaces, UMR 5615, F-69622 (France); Lazar, M. [Université de Lyon, CNRS, Laboratoire Ampère, INSA-Lyon, UMR 5005, F-69621 (France); Toury, B. [Université de Lyon, CNRS, Laboratoire des Multimatériaux et Interfaces, UMR 5615, F-69622 (France); Beaufort, M.F.; Barbot, J.F. [Institut Pprime CNRS - Université de Poitiers - ENSMA - UPR 3346 Département Physique et Mécanique des Matériaux SP2MI 86962 Futuroscope Chasseneuil Cedex (France); Penuelas, J. [Université de Lyon, Institut des Nanotechnologies de Lyon, UMR CNRS 5270, 69134 ECULLY Cedex (France); Planson, D. [Université de Lyon, CNRS, Laboratoire Ampère, INSA-Lyon, UMR 5005, F-69621 (France)

2015-08-30

Highlights: • Growth of Ti{sub 3}SiC{sub 2} thin films onto 4H-SiC (0 0 0 1) 8° and 4°-off substrates. • High temperature application for SiC ohmic contact. • Thermal annealing of Ti{sub -}Al layers. • Influence of the composition in the Ti{sub x}Al{sub 1−x} alloy was investigated. • Influence of the annealing temperature (900–1200 °C) after deposition was investigated. • The structural investigations were mainly performed by using X-ray diffraction (XRD), and transmission electron microscopy (TEM). • Elementary and profile characterization were performed using X-Ray photoelectron spectroscopy (XPS). - Abstract: The growth of Ti{sub 3}SiC{sub 2} thin films was studied onto 4H-SiC (0 0 0 1) 8° and 4°-off substrates by thermal annealing of Ti{sub x}Al{sub 1−x} (0.5 ≤ x ≤ 1) layers. The annealing time was fixed at 10 min under Argon atmosphere. The synthesis conditions were also investigated according to the annealing temperature (900–1200 °C) after deposition. X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM) show that the layer of Ti{sub 3}SiC{sub 2} is epitaxially grown on the 4H-SiC substrate. In addition the interface looks sharp and smooth with evidence of interfacial ordering. Moreover, during the annealing procedure, the formation of unwanted aluminum oxide was detected by using X-Ray Photoelectron Spectroscopy (XPS); this layer can be removed by using a specific annealing procedure.

The effects of composition on the environmental embrittlement of Fe{sub 3}Al alloys

Energy Technology Data Exchange (ETDEWEB)

Alven, D.A.; Stoloff, N.S. [Rensselaer Polytechnic Inst., Troy, NY (United States)

1997-12-01

This paper reviews recent research on embrittlement of iron aluminides at room temperature brought about by exposure to moisture or hydrogen. The tensile and fatigue crack growth behavior of several Fe-28Al-5Cr alloys with small additions of Zr and C are described. It will be shown that fatigue crack growth behavior is dependent on composition, environment, humidity level, and frequency. Environments studied include vacuum, oxygen, hydrogen gas, and moist air. All cases of embrittlement are ultimately traceable to the interaction of hydrogen with the crack tip.

Interdiffusion behaviors of iron aluminide coatings on China low activation martensitic steel

Science.gov (United States)

Zhu, X. X.; Yang, H. G.; Yuan, X. M.; Zhao, W. W.; Zhan, Q.

2014-12-01

The iron aluminide coating on China Low Activation Martensitic (CLAM) steel was prepared by pack cementation and subsequent heat treatment. A surface Fe2Al5 layer was formed on CLAM substrate by pack cementation process with Fe2Al5 donor powder and NH4Cl activator. Diffusion heat treatment was performed in order to allow the phase transformation from Fe2Al5 to a phase with lower aluminum content. Morphology and composition of the coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). There is a need to study the interdiffusion behaviors in these Al containing systems, as a basis for controlling the formation and subsequent degradation of the coating. In this paper, a predictive model was developed to describe the phase transformation of Fe2Al5 as a function of processing parameters. The Wagner's equation was used to calculate the interdiffusion coefficients based on the analysis of the Al concentration profiles. The results showed that the interdiffusion coefficients in the FeAl and α-Fe(Al) phase strongly depends on Al content and showed a maximum at about 28 at.% Al.

Interdiffusion behaviors of iron aluminide coatings on China low activation martensitic steel

International Nuclear Information System (INIS)

Zhu, X.X.; Yang, H.G.; Yuan, X.M.; Zhao, W.W.; Zhan, Q.

2014-01-01

The iron aluminide coating on China Low Activation Martensitic (CLAM) steel was prepared by pack cementation and subsequent heat treatment. A surface Fe 2 Al 5 layer was formed on CLAM substrate by pack cementation process with Fe 2 Al 5 donor powder and NH 4 Cl activator. Diffusion heat treatment was performed in order to allow the phase transformation from Fe 2 Al 5 to a phase with lower aluminum content. Morphology and composition of the coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). There is a need to study the interdiffusion behaviors in these Al containing systems, as a basis for controlling the formation and subsequent degradation of the coating. In this paper, a predictive model was developed to describe the phase transformation of Fe 2 Al 5 as a function of processing parameters. The Wagner’s equation was used to calculate the interdiffusion coefficients based on the analysis of the Al concentration profiles. The results showed that the interdiffusion coefficients in the FeAl and α-Fe(Al) phase strongly depends on Al content and showed a maximum at about 28 at.% Al