Grain size stability and hardness in nanocrystalline Cu–Al–Zr and Cu–Al–Y alloys

International Nuclear Information System (INIS)

Roy, D.; Mahesh, B.V.; Atwater, M.A.; Chan, T.E.; Scattergood, R.O.; Koch, C.C.

2014-01-01

Cryogenic high energy ball milling has been used to synthesize nanocrystalline Cu–14Al, Cu–12Al–2Zr and Cu–12Al–2Y alloys by mechanical alloying. The alloys were studied with the aim of comparing the effect of substituting Y and Zr in place of Al, in Cu–Al alloys, on the grain size stability at elevated temperatures. The as-milled alloys were subjected to annealing at various temperatures between 200 and 900 °C and the resulting grain morphology has been studied using X-ray diffraction and transmission electron microscopy. The addition of Y results in significantly reduced susceptibility to grain growth whereas in case of CuAl and CuAlZr alloys, the susceptibility to grain growth was much higher. The hardness is substantially increased due to Zr and Y addition in the as-milled CuAl powders. However, the hardness of Cu–12Al–2Zr gradually decreases and approaches that of Cu–14Al alloy after the annealing treatment whereas in case of Cu–12Al–2Y alloy, the relative drop in the hardness is much lower after annealing. Accordingly, the efficacy of grain size stabilization by Y addition at high homologous temperatures has been explained on the basis of a recent thermodynamic stabilization models

Mechanical properties of Y2O3-doped W-Ti alloys

International Nuclear Information System (INIS)

Aguirre, M.V.; Martin, A.; Pastor, J.Y.; LLorca, J.; Monge, M.A.; Pareja, R.

2010-01-01

W and W alloys are currently considered promising candidates for plasma facing components in future fusion reactors but most of the information on their mechanical properties at elevated temperature was obtained in the 1960s and 1970s. In this investigation, the strength and toughness of novel Y 2 O 3 -doped W-Ti alloys manufactured by powder metallurgy were measured from 25 o C up to 1000 o C in laboratory air and the corresponding deformation and failure micromechanisms were ascertained from analyses of the fracture surfaces. Although the materials were fairly brittle at ambient temperature, the strength and toughness increased with temperature and Ti content up to 600 o C. Beyond this temperature, oxidation impaired the mechanical properties but the presence of Y 2 O 3 enhanced the strength and toughness retention up to 800 o C.

RLE (Research Laboratory of Electronics) Progress Report Number 129.

Science.gov (United States)

1987-01-01

27709 ELEMENT NO. NO. NO. NO. 1. TITLE finciade SeciantV Ciiiiiiificationt Progress Report.No. 129 12. PERSONAL AUTHORI(S) Jonathan Allen, Daniel...TMIS PAGE *~ ~ d 1 ". d4 ’V. ~a PI al . 1 AN *,.i **N %** RLE Progress Report No. 129 January 1987 Submitted by: Prof. Jonathan Allen Prof. Daniel...Clevenger, J. Floro, S.M. Garrison, J. Im, K. Ismail, H. Kahn, H.J. Kim, Y.C. Ku, J.C. Licini, U. Meirav, J.E. Palmer, S.L. Park, H.M. Quek , J. Scott

Iodine-129 in the environment

International Nuclear Information System (INIS)

Tikhomirov, F.A.; Moiseev, I.T.

1987-01-01

The quantitative ratio of aerial and soil entries of 129 I into plants, parameters of its migration in the system of atmosphere-soil-plants-river water, dynamics of transformation and biological availability of 129 I in soil for plants were studied on the basis of field observations and experiments using the radioactive tracers. The doses of human thyroid gland irradiation by 129 I under atmospheric and soil pathways of its transport into diet are estimated. 129 I content in soil due to its systematic, for 50 years, releases into atmosphere is shown to be negligible, agricultural production contamination by 129 I resulting mainly from its fallout onto overground phytomass. The period, needed to achieve 129 I concentration equilibrium in the atmosphere-soil system under constant average 129 I content in the air, varies depending on the soil type from several hundred years (for podzolic soils) up to several thousand years (for chernozem). The 129 I half-accumulation period is equal to 150 years for soddy-podzolic soil and to 700 years for chernozem. In case of 129 I fallout lasting for 100 years the annual increase of its content in overground phytomass due to the transport from soil will account for 0,3% of its atmospheric entry way for soddy-podzolic soil and for 0,1% for chernozem, respectively. For a number of sierozem, yellow soil and calcareous chernozem types this addition is higher (up to 1%). Under constant iodine-129 concentration in air (1 Bq/m3) the absorbed dose for one-year child's thyroid gland in continental area is approximately equal to 2 (Gy/y)/(Bq/m3). The absorbed dose from globally dissipated 129 I under 99% efficiency of gas purification will not exceed 2·10 -7 Gy/y. The input of globally dissipated 129 I, originating from deep underground disposal of nuclear wastes can account for not more than 10 -9 Gy/y. In total, 129 I releases for the coming century is not going to produce limitations for nuclear energetics development. (author)

Effect of CaO on Hot Workability and Microstructure of Mg-9.5Zn-2Y Alloy

Science.gov (United States)

Kwak, Tae-yang; Kim, Daeguen; Yang, Jaehack; Yoon, Young-ok; Kim, Shae K.; Lim, Hyunkyu; Kim, Woo Jin

Mg-Zn-Y system alloys have been a great interest because Mg-Zn-Y alloys with I-phase exhibited high ductility at room and elevated temperatures. According to our preliminary experiments, the addition of CaO improved strength, but the process window became narrow. Therefore, the aim of current work was to find optimum extrusion conditions for CaO added Mg-Zn-Y alloys by processing maps. The 0.3 wt.% of CaO added Mg-9.5Zn-2Y (Mg95.6Zn3.8Y0.6) alloy was prepared by casting into steel mold and homogenizing. Hot compression test were performed in the Gleeble machine at temperature range of 250-400 °C with various strain rates. The alloys were extruded with a reduction ratio of 20:1. To analyze the microstructure and texture, optical micrograph, scanning electron microscope and electron backscattered diffraction were used. Moreover, we investigated the effects of metallic Ca addition in this alloy to compare with the addition of CaO.

Microstructural changes of Y-doped V-4Cr-4Ti alloys after ion and neutron irradiation

Directory of Open Access Journals (Sweden)

H. Watanabe

2016-12-01

Full Text Available High-purity Y-doped V-4Cr-4Ti alloys (0.1–0.2wt. % Y, manufactured by the National Institute for Fusion Science (NIFS, were used for this study. Heavy-ion and fission-neutron irradiation was carried out at temperatures 673–873K. During the ion irradiation at 873K, the microstructure was controlled by the formation of Ti(C,O,N precipitates lying on the (100 plane. Y addition effectively suppressed the growth of Ti(C,O,N precipitates, especially at lower dose irradiation to up to 4 dpa. However, at higher dose levels (12.0 dpa, the number density was almost at the same levels irrespective of the presence of Y. After neutron irradiation at 873K, fine titanium oxides were also observed in all V alloys. However, smaller oxide sizes were observed in the Y-doped samples under the same irradiation conditions. The detailed analysis of EDS showed that the center of the Ti(C,O,N precipitates was mainly enriched by nitrogen. The results showed that the contribution of not only oxygen atoms picked up from the irradiation environment but also nitrogen atoms is essential to understand the microstructural evolution of V-4Cr-4Ti-Y alloys.

Mechanical properties of tungsten alloys with Y2O3 and titanium additions

International Nuclear Information System (INIS)

Aguirre, M.V.; Martin, A.; Pastor, J.Y.; LLorca, J.; Monge, M.A.; Pareja, R.

2011-01-01

In this research the mechanical behaviour of pure tungsten (W) and its alloys (2 wt.% Ti-0.47 wt.% Y 2 O 3 and 4 wt.% Ti-0.5 wt.% Y 2 O 3 ) is compared. These tungsten alloys, have been obtained by powder metallurgy. The yield strength, fracture toughness and elastic modulus have been studied in the temperature interval of 25 deg. C to 1000 deg. C. The results have shown that the addition of Ti substantially improves the bending strength and toughness of W, but it also dramatically increases the DBTT. On the other hand, the addition of 0.5% Y 2 O 3 , is enough to improve noticeably the oxidation behaviour at the higher temperatures. The grain size, fractography and microstructure are studied in these materials. Titanium is a good grain growth inhibitor and effective precursor of liquid phase in HIP. The simultaneous presence of Y 2 O 3 and Ti permits to obtain materials with low pores presence.

Study on microstructure and strengthening mechanism of AZ91-Y magnesium alloy

Science.gov (United States)

Cai, Huisheng; Guo, Feng; Su, Juan; Liu, Liang; Chen, Baodong

2018-03-01

AZ91-Y magnesium alloy with different thicknesses were prepared by die casting process. The main existence forms of Y in alloy and the effects of Y on microstructure and mechanical properties of alloy were studied, the main reason for the change of mechanical properties and fracture mechanism were analyzed. The results show that, yttrium exists mainly in the forms of Al2Y phase and trace solid solution in α-Mg. Yttrium can refine the grain of α-Mg, reduce the amount of eutectic β-Mg17Al12 phase and promote its discrete distribution. The room temperature tensile strength and elongation of alloy increased first and then decreased with the increase of Y content. The designed alloys containing 0.6% Y (measured containing 0.63% Y) have better mechanical properties. The change of mechanical properties of alloy is a comprehensive reflection of the effect of solid solution, grain refinement and second phase. The cracking of Al2Y phase and β-Mg17Al12 phase and crack propagation through Al2Y phase and β-Mg17Al12 phase are the main fracture mechanism of magnesium alloy containing yttrium. The cooling rate does not change the trend of the influence of Y, but affects the degree of influence of Y.

Corrosion testing of NiCrAl(Y) coating alloys in high-temperature and supercritical water

International Nuclear Information System (INIS)

Biljan, S.; Huang, X.; Qian, Y.; Guzonas, D.

2011-01-01

With the development of Generation IV (Gen IV) nuclear power reactors, materials capable of operating in high-temperature and supercritical water environment are essential. This study focuses on the corrosion behavior of five alloys with compositions of Ni20Cr, Ni5Al, Ni50Cr, Ni20Cr5Al and Ni20Cr10AlY above and below the critical point of water. Corrosion tests were conducted at three different pressures, while the temperature was maintained at 460 o C, in order to examine the effects of water density on the corrosion. From the preliminary test results, it was found that the binary alloys Ni20Cr and Ni50Cr showed weight loss above the critical point (23.7 MPa and 460 o C). The higher Cr content alloy Ni50Cr suffered more weight loss than Ni-20Cr under the same conditions. Accelerated weight gain was observed above the critical point for the binary alloy Ni5Al. The combination of Cr, Al and Y in Ni20Cr10AlY provides stable scale formation under all testing conditions employed in this study. (author)

Mechanical properties of Y{sub 2}O{sub 3}-doped W-Ti alloys

Energy Technology Data Exchange (ETDEWEB)

Aguirre, M.V. [Departamento de Tecnologias Especiales Aplicadas a la Aeronautica, Universidad Politecnica de Madrid, Escuela de Ingenieria Aeronautica y del Espacio, 28040 Madrid (Spain); Martin, A.; Pastor, J.Y. [Departamento de Ciencia de Materiales-CISDEM, Universidad Politecnica de Madrid, E. T. S. de Ingenieros de Caminos, 28040 Madrid (Spain); LLorca, J., E-mail: jllorca@mater.upm.e [Departamento de Ciencia de Materiales-CISDEM, Universidad Politecnica de Madrid, E. T. S. de Ingenieros de Caminos, 28040 Madrid (Spain); Instituto Madrileno de Estudios Avanzados de Materiales (Instituto IMDEA Materiales), C/ Profesor Aranguren s/n, 28040 Madrid (Spain); Monge, M.A.; Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

2010-09-30

W and W alloys are currently considered promising candidates for plasma facing components in future fusion reactors but most of the information on their mechanical properties at elevated temperature was obtained in the 1960s and 1970s. In this investigation, the strength and toughness of novel Y{sub 2}O{sub 3}-doped W-Ti alloys manufactured by powder metallurgy were measured from 25 {sup o}C up to 1000 {sup o}C in laboratory air and the corresponding deformation and failure micromechanisms were ascertained from analyses of the fracture surfaces. Although the materials were fairly brittle at ambient temperature, the strength and toughness increased with temperature and Ti content up to 600 {sup o}C. Beyond this temperature, oxidation impaired the mechanical properties but the presence of Y{sub 2}O{sub 3} enhanced the strength and toughness retention up to 800 {sup o}C.

Crystallization Behavior of A Bulk Amorphous Mg62Cu26Y12 Alloy

Science.gov (United States)

Wu, Shyue-Sheng; Chin, Tsung-Shune; Su, Kuo-Chang

1994-07-01

The crystallization temperature, the associated activation energy and the crystallized structure of a bulk amorphous Mg62Cu26Y12 alloy with a diameter of 2.5 mm were studied. It possesses a one-step crystallization behavior. The crystallization reaction was found to be represented by: AM(MG62Cu26Y12)→Mg2Cu+MgY+CuY+Mg, ( Tx=188°C, Eac=134 kJ/mol) where AM represents the amorphous state, T x the crystallization temperature at an infinitesimal heating rate, and E ac the associated activation energy. The amount of crystalline phases were found to be Mg2Cu:MgY:CuY=76:17:7. The Mg phase is identifiable only by high resolution electron microscopy, not by X-ray diffraction. The crystallization leads to a sharp rise in electrical resistivity which is reversed to those of iron-based amorphous alloys.

The relation between ductility and stacking fault energies in Mg and Mg–Y alloys

International Nuclear Information System (INIS)

Sandlöbes, S.; Friák, M.; Zaefferer, S.; Dick, A.; Yi, S.; Letzig, D.; Pei, Z.; Zhu, L.-F.; Neugebauer, J.; Raabe, D.

2012-01-01

The underlying mechanisms that are responsible for the improved room-temperature ductility in Mg–Y alloys compared to pure Mg are investigated by transmission electron microscopy and density functional theory. Both methods show a significant decrease in the intrinsic stacking fault I 1 energy (I 1 SFE) with the addition of Y. The influence of the SFE on the relative activation of different competing deformation mechanisms (basal, prismatic, pyramidal slip) is discussed. From this analysis we suggest a key mechanism which explains the transition from primary basal slip in hexagonal close-packed Mg to basal plus pyramidal slip in solid solution Mg–Y alloys. This mechanism is characterized by enhanced nucleation of 〈c + a〉 dislocations where the intrinsic stacking fault I 1 (ISF 1 ) acts as heterogeneous source for 〈c + a〉 dislocations. Possible electronic and geometric reasons for the modification of the SFE by substitutional Y atoms are identified and discussed.

High heat load properties of TiC dispersed Mo alloys

International Nuclear Information System (INIS)

Tokunaga, Kazutoshi; Yoshida, Naoaki; Miura, Yasushi; Kurishita, Hiroaki; Kitsunai, Yuji; Kayano, Hideo.

1996-01-01

Electron beam high heat load experiment of new developed three kinds of TiC dispersed Mo alloys (Mo-0.1wt%TiC, Mo-0.5wt%TiC and Mo-1.0wt%TiC) was studied so as to evaluate it's high heat load at using as the surface materials of divertor. The obtained results indicated that cracks were not observed by embrittlement by recrystallization until about 2200degC of surface temperature and the gas emission properties were not different from sintered molibdenum. However, at near melting point, deep cracks on grain boundary and smaller gas emission than that of sintered Mo were observed. So that, we concluded that TiC dispersed Mo alloy was good surface materials used under the conditions of the stationary heat flux and less than the melting point, although not good one to be melted under nonstationary large heat flux. (S.Y.)

High-temperature deformation of a mechanically alloyed niobium-yttria alloy

International Nuclear Information System (INIS)

Chou, I.; Koss, D.A.; Howell, P.R.; Ramani, A.S.

1997-01-01

Mechanical alloying (MA) and hot isostatic pressing have been used to process two Nb alloys containing yttria particles, Nb-2 vol.%Y 2 O 3 and Nb-10 vol.%Y 2 O 3 . Similar to some thermomechanically processed nickel-based alloys, both alloys exhibit partially recrystallized microstructures, consisting of a 'necklace' of small recrystallized grains surrounding much larger but isolated, unrecrystallized, cold-worked grains. Hot compression tests from 1049 to 1347 C (0.5-0.6T MP ) of the 10% Y 2 O 3 alloy show that MA material possesses a much higher yield and creep strength than its powder-blended, fully recrystallized counterpart. In fact, the density-compensated specific yield strength of the MA Nb-10Y 2 O 3 exceeds that of currently available commercial Nb alloys. (orig.)

Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys

International Nuclear Information System (INIS)

Geribola, Gulherme Altomari

2014-01-01

Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H 2 /2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

Selective Internal Oxidation and Severe Plastic Deformation of Multiphase Fe-Y Alloys

Science.gov (United States)

Kachur, Stephen J.

Oxide dispersion strengthened (ODS) alloys are known for their desirable mechanical properties and unique microstructures. These alloys are characterized by an even dispersion of oxide phase throughout a metallic matrix, and exhibit high strength and enhanced creep properties at elevated temperatures. This makes them ideal candidate materials for use in many structural applications, such as coal-fired power plants or in next generation nuclear reactors. Currently most often produced by mechanical alloying, a powder metallurgy based process that utilizes high energy ball milling, these alloys are difficult and costly to produce. One proposed method for forming ODS alloys without high-energy ball milling is to internally oxidize a bulk alloy before subjecting it to severe plastic deformation to induce an even oxide distribution. This work examines such a processing scheme with a focus on the internal oxidation behavior. Internal oxidation has been shown to occur orders of magnitude faster than expected in multi-phase alloys where a highly reactive oxidizable solute has negligible solubility and diffusivity in other, more-noble, phases. Commonly referred to as in situ oxidation, this accelerated oxidation process has potential for use in a processing scheme for ODS alloys. While in situ oxidation has been observed in many different alloy systems, a comprehensive study of alloy composition and microstructure has not been performed to describe the unusual oxidation rates. This work used Fe-Y binary alloys as model system to study effects of composition and microstructure. These alloys have been shown to exhibit in situ oxidation, and additionally, Y is typically introduced during mechanical alloying to form Y-rich oxides in Fe-based ODS alloys. Alloys with Y content between 1.5 and 15 wt% were prepared using a laboratory scale arc-melting furnace. These alloys were two phase mixtures of Fe and Fe17Y2. First, samples were oxidized between 600 and 800 °C for 2 to 72

Fabrication of V-Cr-Ti-Y-Al-Si alloys by levitation melting

Energy Technology Data Exchange (ETDEWEB)

Chuto, Toshinori; Satou, Manabu; Abe, Katsunori [Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Miyagi (Japan); Nagasaka, Takuya; Muroga, Takeo [National Inst. for Fusion Science, Toki, Gifu (Japan); Shibayama, Tamaki [Center for Advanced Research of Energy Technology, Hokkaido University, Sapporo, Hokkaido (Japan); Tomiyama, Shigeki [Daido Bunseki Research Inc., Nagoya, Aichi (Japan); Sakata, Masafumi [Daido Steel Co. Ltd., Nagoya (Japan)

2000-09-01

Three allows of V-4Cr-4Ti type containing Si, Al and Y were fabricated by 2.5 kg scale levitation melting in this study. Workability and recrystallization behavior of the alloys were studied in order to establish the fabrication method of high-purity large ingot of V-Cr-Ti-Si-Al-Y type alloys, especially reducing interstitial impurity levels. Oxygen contents decreased with increasing yttrium contents and were kept below 180 mass ppm over wide region in the ingots. Nitrogen contents in the V-Cr-Ti-Y-Si-Al type alloys were only 100 mass ppm, which were as low as that in the starting materials. Only the V-4Cr-4Ti-0.1Y, Si, Al alloy could be cold-rolled at as-melted condition. Because large yttrium inclusions were observed in the alloys containing 0.5 mass%Y, it is necessary to optimize yttrium contents to avoid large inclusions and to obtain good workability. (author)

Fabrication of V-Cr-Ti-Y-Al-Si alloys by levitation melting

International Nuclear Information System (INIS)

Chuto, Toshinori; Satou, Manabu; Abe, Katsunori; Nagasaka, Takuya; Muroga, Takeo; Shibayama, Tamaki; Tomiyama, Shigeki; Sakata, Masafumi

2000-01-01

Three allows of V-4Cr-4Ti type containing Si, Al and Y were fabricated by 2.5 kg scale levitation melting in this study. Workability and recrystallization behavior of the alloys were studied in order to establish the fabrication method of high-purity large ingot of V-Cr-Ti-Si-Al-Y type alloys, especially reducing interstitial impurity levels. Oxygen contents decreased with increasing yttrium contents and were kept below 180 mass ppm over wide region in the ingots. Nitrogen contents in the V-Cr-Ti-Y-Si-Al type alloys were only 100 mass ppm, which were as low as that in the starting materials. Only the V-4Cr-4Ti-0.1Y, Si, Al alloy could be cold-rolled at as-melted condition. Because large yttrium inclusions were observed in the alloys containing 0.5 mass%Y, it is necessary to optimize yttrium contents to avoid large inclusions and to obtain good workability. (author)

Effect of mechanical alloying on FeCrC reinforced Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, S. Osman [Univ. of Namik Kemal, Tekirdag (Turkey); Teker, Tanju [Adiyaman Univ. (Turkey). Dept. of Metallurgical and Materials Engineering; Demir, Fatih [Batman Univ. (Turkey)

2016-05-01

Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing and rewelding of powder particles in a high-energy ball mill. In the present study, the intermetallic matrix composites (IMCs) of Ni-Al reinforced by M{sub 7}C{sub 3} were produced by powder metallurgical routes via solid state reaction of Ni, Al and M{sub 7}C{sub 3} particulates by mechanical alloying processes. Ni, Al and M{sub 7}C{sub 3} powders having 100 μm were mixed, mechanical alloyed and the compacts were combusted in a furnace. The mechanically alloyed (MAed) powders were investigated by X-ray diffraction (XRD), microhardness measurement, optic microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The presence of the carbides depressed the formation of unwanted NiAl intermetallic phases. The mechanical alloyed M{sub 7}C{sub 3} particles were unstable and decomposed partially within the matrix during alloying and sintering, and the morphology of the composites changed with the dissolution ratio of M{sub 7}C{sub 3} and sintering temperature.

Synthesis Of NiCrAlC alloys by mechanical alloying

International Nuclear Information System (INIS)

Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M.

2010-01-01

The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni 3 Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

Mechanical properties of tungsten alloys with Y{sub 2}O{sub 3} and titanium additions

Energy Technology Data Exchange (ETDEWEB)

Aguirre, M.V., E-mail: mariavega.aguirre@upm.es [Departamento de Tecnologias Especiales Aplicadas a la Aeronautica, Universidad Politecnica de Madrid, E.U.I.T. Aeronautica, 28040 Madrid (Spain); Martin, A.; Pastor, J.Y. [Departamento de Ciencia de Materiales-CISDEM, Universidad Politecnica de Madrid.E.T.S. Ingenieros de Caminos, 28040 Madrid (Spain); LLorca, J. [Departamento de Ciencia de Materiales-CISDEM, Universidad Politecnica de Madrid.E.T.S. Ingenieros de Caminos, 28040 Madrid (Spain); Instituto Madrileno de Estudios Avanzados en Materiales (Instituto IMDEA-Materiales), Ingenieros de Caminos, 28040 Madrid (Spain); Monge, M.A.; Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

2011-10-01

In this research the mechanical behaviour of pure tungsten (W) and its alloys (2 wt.% Ti-0.47 wt.% Y{sub 2}O{sub 3} and 4 wt.% Ti-0.5 wt.% Y{sub 2}O{sub 3}) is compared. These tungsten alloys, have been obtained by powder metallurgy. The yield strength, fracture toughness and elastic modulus have been studied in the temperature interval of 25 deg. C to 1000 deg. C. The results have shown that the addition of Ti substantially improves the bending strength and toughness of W, but it also dramatically increases the DBTT. On the other hand, the addition of 0.5% Y{sub 2}O{sub 3}, is enough to improve noticeably the oxidation behaviour at the higher temperatures. The grain size, fractography and microstructure are studied in these materials. Titanium is a good grain growth inhibitor and effective precursor of liquid phase in HIP. The simultaneous presence of Y{sub 2}O{sub 3} and Ti permits to obtain materials with low pores presence.

Microstructure and mechanical properties of a Mg–Zn–Y alloy produced by a powder metallurgy route

Energy Technology Data Exchange (ETDEWEB)

Asgharzadeh, H. [Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, P.O. Box 51666-16471, Tabriz (Iran, Islamic Republic of); Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Yoon, E.Y. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Chae, H.J.; Kim, T.S. [Korea Institute for Rare Metals, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Lee, J.W. [Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Kim, H.S., E-mail: hskim@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2014-02-15

In this paper, a bulk Mg–Zn–Y alloy reinforced by quasicrystalline particles was produced by hot extrusion of rapidly-solidified powders. MgZn{sub 4.3}Y{sub 0.7} powders with different particle sizes were prepared by an inert gas atomizer and then extruded at 380 °C with extrusion ratios of 10:1, 15:1, and 20:1. Microstructural studies were performed using an optical microscope, scanning electron microscope, transmission electron microscope, and X-ray diffraction. The mechanical strength and hardness of the extruded materials were enhanced by employing finer Mg alloy powders. More uniform deformation of powders in extruded billets with good tensile properties was achieved at higher extrusion ratios, especially for finer powders. The high strength of the MgZn{sub 4.3}Y{sub 0.7} alloy was preserved at elevated temperatures due to the presence of icosahedral phase nanoparticles.

MO-HF-C alloy composition

International Nuclear Information System (INIS)

Whelan, E.P.; Kalns, E.

1987-01-01

This patent describes, as an article of manufacture, a cast ingot of a molybdenum-hafnium-carbon alloy consisting essentially by weight of about 0.6% to about 1% Hf, about 0.045% to about 0.08% C, and the balance essentially molybdenum. The amount of Hf and C present are substantially stoichiometric with respect to HfC and within about +-15% of stoichiometry. The ingot is characterized in that it has a substantially less tendency to crack compared to alloys containing Hf in excess of about 1% by weight and carbon in excess of 0.08% by weight, without substantial diminution in strength properties of the alloy

Irradiation creep of various ferritic alloys irradiated at {approximately}400{degrees}C in the PFR and FFTF reactors

Energy Technology Data Exchange (ETDEWEB)

Toloczko, M.B.; Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States); Eiholzer, C.R. [Westinghouse Hanford Company, Richland, WA (United States)

1997-04-01

Three ferritic alloys were irradiated in two fast reactors to doses of 50 dpa or more at temperatures near 400{degrees}C. One martensitic alloy, HT9, was irradiated in both the FFTF and PFR reactors. PFR is the Prototype Fast Reactor in Dourneay, Scotland, and FFTF is the Fast Flux Test Facility in Richland, WA. D57 is a developmental alloy that was irradiated in PFR only, and MA957 is a Y{sub 2}O{sub 3} dispersion-hardened ferritic alloy that was irradiated only in FFTF. These alloys exhibited little or no void swelling at {approximately}400{degrees}C. Depending on the alloy starting condition, these steels develop a variety of non-creep strains early in the irradiation that are associated with phase changes. Each of these alloys creeps at a rate that is significantly lower than that of austenitic steels irradiated in the same experiments. The creep compliance for ferritic alloys in general appears to be {approximately}0.5 x 10{sup {minus}6} MPa{sup {minus}1} dpa{sup {minus}1}, independent of both composition and starting state. The addition of Y{sub 2}O{sub 3} as a dispersoid does not appear to change the creep behavior.

Formation and evolution of the hardening precipitates in a Mg-Y-Nd alloy

International Nuclear Information System (INIS)

Barucca, G.; Ferragut, R.; Fiori, F.; Lussana, D.; Mengucci, P.; Moia, F.; Riontino, G.

2011-01-01

The formation and evolution of hardening precipitates in a Mg-Y-Nd (WE43) alloy during artificial ageing at 150 and 210 deg. C is followed by small angle X-ray scattering (SAXS) measurements, Vickers microhardness tests and transmission electron microscopy (TEM) observations. A quantitative description of the alloy studied during the early and advanced stages of the precipitation sequence is presented. In situ SAXS evolution at 210 deg. C of the size, volume fraction and number density of the subnanometer and nanometer particles that evolve in the β'' phase was obtained. TEM and microhardness results indicate that the hardening mechanism is based on β'' transformation of pre-precipitates and their growth at 150 deg. C, while at 210 deg. C hardening is mainly associated with β'' → β' transformation.

Progress in AMS measurement of "1"2"9I and "1"4C at CIAE

International Nuclear Information System (INIS)

Yang Xuran; Dong, K.J.; Shan, J.; He Ming; Xie, L.B.

2013-01-01

Twenty-four years have passed since the AMS was built at China Institute of Atomic Energy (CIAE) in 1989. We have measured "2"3"6U, "1"8"2Hf, "5"9Ni and other elements. Recently, the routine method of measuring the "1"2"9I concentration in air particle samples using AMS have been set up due to it has great advantages to measure long-lived radioisotopes. For the applications, "1"2"9I could be used for monitoring nuclear environment. "1"2"9I was collected in air particle samples after the accident of Fukushima nuclear power plant and measured at the China Institute of Atomic Energy (CIAE) by using AMS, the result show that "1"2"9I derived from FNPP accident had been arrived in Beijing early on March 26th and "1"2"9I concentration had been greatly increased relative to March 20th. On the other hand, a new system to measure "1"4C of AMS will be designed for the application in bio-medical science: urea breath test (UBT). UBT has been carried out widely by using carbon isotope of "1"3C and "1"4C, respectively, in the world. They are two tracers with different measurement methods but applied by the same principle. Optimizing UBT methods with using "1"4C is the priori for the diagnosis of helicobacter pylori in the future. (author)

Atomic investigation of alloying Cr, Ti, Y additions in a grain boundary of vanadium

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pengbo, E-mail: zhangpb@dlmu.edu.cn [Department of Physics, Dalian Maritime University, Dalian 116026 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Li, Xiaojie; Zhao, Jijun [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Zheng, Pengfei; Chen, Jiming [Southwestern Institute of Physics, Chengdu 610041 (China)

2016-01-15

The effect of alloying additions (Cr, Ti and Y) in a vanadium (V) ∑3 (111) grain boundary (GB) is investigated by first-principles calculations. To determine site preference and segregation properties of Cr, Ti and Y in the GB and bulk, we calculate the formation energies and segregation energies for different interstitial and substitutional sites. Cr/Ti/Y atom prefers to segregate to the substitutional sites of the GB from bulk environment, whereas Cr segregation to GB is very weak. Based on the Rice and Wang's model, Cr acts as the GB cohesion, while Ti and Y are strong embrittlers. The analysis of atomic and electronic structures provides a reasonable expansion for the embrittlement behavior. Moreover, the effect of Cr, Ti and Y in the GB on solution of interstitial impurities C, N, O, H, and He are determined. The results show that Cr restrains solution of these impurities in the GB, while Ti tends to form Ti–N complex by absorbing N impurities and Y can absorbs O and He impurities. The present calculations are helpful for understanding the behavior of alloying Cr, Ti, Y additions at the grain boundary of vanadium.

Influence of Cr and Y Addition on Microstructure, Mechanical Properties, and Corrosion Resistance of SPSed Fe-Based Alloys

Science.gov (United States)

Muthaiah, V. M. Suntharavel; Mula, Suhrit

2018-03-01

Present work investigates the microstructural stability during spark plasma sintering (SPS) of Fe-Cr-Y alloys, its mechanical properties and corrosion behavior for its possible applications in nuclear power plant and petrochemical industries. The SPS was carried out for the Fe-7Cr-1Y and Fe-15Cr-1Y alloys at 800 °C, 900 °C, and 1000 °C due to their superior thermal stability as reported in Muthaiah et al. [Mater Charact 114:43-53, 2016]. Microstructural analysis through TEM and electron back scattered diffraction confirmed that the grain sizes of the sintered samples depicted a dual size grain distribution with >50 pct grains within a range of 200 nm and remaining grains in the range 200 nm to 2 µm. The best combination of hardness, wear resistance, and corrosion behavior was achieved for the samples sintered at 1000 °C. The high hardness (9.6 GPa), minimum coefficient of friction (0.25), and extremely low wear volume (0.00277 × 10-2 mm3) and low corrosion rate (3.43 mpy) are discussed in the light of solid solution strengthening, grain size strengthening, grain boundary segregation, excellent densification due to diffusion bonding, and precipitation hardening due to uniformly distributed nanosize Fe17Y2 phase in the alloy matrix. The SEM analysis of the worn surface and corroded features corroborated well with the wear resistance and corrosion behavior of the corresponding samples.

Stability of rapidly quenched and hydrogenated Mg-Ni-Y and Mg-Cu-Y alloys in extreme alkaline medium

International Nuclear Information System (INIS)

Gebert, A.; Khorkounov, B.; Wolff, U.; Mickel, Ch.; Uhlemann, M.; Schultz, L.

2006-01-01

Amorphous-nanocrystalline Mg 50 Ni 30 Y 20 and Mg 63 Ni 30 Y 7 and amorphous Mg 65 Cu 25 Y 10 alloys were produced by melt-spinning and characterized regarding their microstructure and thermal behaviour using XRD, TEM and DSC. Their electrochemical behaviour in the as-quenched state and after hydrogen charging at -25 mA/cm 2 for up to 20 h was studied in electrolytes with pH 5-7 and 13, but mainly in a battery electrolyte: 6 M KOH with pH 14.8 by means of anodic and cathodic polarization measurements. In the as-quenched state, the highest alloys stability was observed at pH 13. At pH 14.8, gradual oxidation and dissolution of copper or nickel governs the anodic behaviour before a passive state is attained. The dissolution of nickel is much more inhibited than that of copper due to its lower tendency to form soluble oxidized ions and to a stabilizing effect of higher fractions of yttrium in the alloy on the passivation. By galvanostatic charging, the Mg 65 Cu 25 Y 10 alloy shows the highest hydrogen absorption capacity followed by Mg 50 Ni 30 Y 20 and Mg 63 Ni 30 Y 7 . During the charging process, the alloys exhibit a change in the surface state chemistry, i.e. an enrichment of nickel- or copper-rich species, causing preferential oxidation and dissolution during subsequent exposure under free corrosion and anodic conditions. Mg-Ni-Y alloys demonstrate a higher stability during this treatment in extreme alkaline medium. The reasons for this and consequences regarding the use as electrode materials are discussed in detail

Formation and evolution of the hardening precipitates in a Mg-Y-Nd alloy

Energy Technology Data Exchange (ETDEWEB)

Barucca, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Ferragut, R. [Dipartimento di Fisica, LNESS and CNISM, Politecnico di Milano, Via Anzani 42, I-22100 Como (Italy); Fiori, F. [Dipartimento SAIFET, Sezione di Scienze Fisiche, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Lussana, D. [Dipartimento di Chimica IFM and NIS Centre, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy); Mengucci, P., E-mail: p.mengucci@univpm.it [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Moia, F. [Dipartimento di Fisica, LNESS and CNISM, Politecnico di Milano, Via Anzani 42, I-22100 Como (Italy); Riontino, G. [Dipartimento di Chimica IFM and NIS Centre, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy)

2011-06-15

The formation and evolution of hardening precipitates in a Mg-Y-Nd (WE43) alloy during artificial ageing at 150 and 210 deg. C is followed by small angle X-ray scattering (SAXS) measurements, Vickers microhardness tests and transmission electron microscopy (TEM) observations. A quantitative description of the alloy studied during the early and advanced stages of the precipitation sequence is presented. In situ SAXS evolution at 210 deg. C of the size, volume fraction and number density of the subnanometer and nanometer particles that evolve in the {beta}'' phase was obtained. TEM and microhardness results indicate that the hardening mechanism is based on {beta}'' transformation of pre-precipitates and their growth at 150 deg. C, while at 210 deg. C hardening is mainly associated with {beta}'' {yields} {beta}' transformation.

Microstructure and Mechanical Properties of Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-x Y Alloys.

Science.gov (United States)

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

2018-09-01

Magnesium and its alloys are potential candidates for many automotive and aerospace applications due to their low density and high specific strength. However, the use of magnesium as wrought products is limited because of its poor workability at ambient temperatures. Mg-Li alloys containing 5-11 wt.% Li exhibit a two-phase structure consisting of a α (hcp) Mg-rich phase and a β (bcc) Li-rich phase. Mg-Li alloys with Li content greater than 11 wt.% exhibit a single-phase structure consisting of only the β phase. In the present study, we studied the effects of Y addition on the microstructure and mechanical properties of Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca based alloys. The melt was maintained at 720 °C for 20 min and poured into a mold. Then, the as-cast Mg alloys were homogenized at 350 °C for 4 h and were hot-extruded onto a 4-mm-thick plate with a reduction ratio of 14:1. The as-cast Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-xY (x 0, 1, 3, and 5 wt.%) alloys were composed of α-Mg, β-Li, γ-Mg2Zn3Li, I-Mg3YZn6, W-Mg3Y2Zn3, and X-Mg12YZn phases. By increasing the Y content from 0 to 5 wt.%, the composition of the W-Mg3Y2Zn3 phase increased. With increasing Y content, from 0 to 1, 3, and 5 wt.%, the average grain size and ultimate tensile of the as-extruded Mg alloys decreased slightly, from 8.4, to 3.62, 3.56, and 3.44 μm and from 228.92 to 215.57, 187.47, and 161.04 MPa, respectively, at room temperature.

Spontaneous autoimmunity in 129 and C57BL/6 mice-implications for autoimmunity described in gene-targeted mice.

Directory of Open Access Journals (Sweden)

Anne E Bygrave

2004-08-01

Full Text Available Systemic lupus erythematosus (SLE is a multisystem autoimmune disorder in which complex genetic factors play an important role. Several strains of gene-targeted mice have been reported to develop SLE, implicating the null genes in the causation of disease. However, hybrid strains between 129 and C57BL/6 mice, widely used in the generation of gene-targeted mice, develop spontaneous autoimmunity. Furthermore, the genetic background markedly influences the autoimmune phenotype of SLE in gene-targeted mice. This suggests an important role in the expression of autoimmunity of as-yet-uncharacterised background genes originating from these parental mouse strains. Using genome-wide linkage analysis, we identified several susceptibility loci, derived from 129 and C57BL/6 mice, mapped in the lupus-prone hybrid (129 x C57BL/6 model. By creating a C57BL/6 congenic strain carrying a 129-derived Chromosome 1 segment, we found that this 129 interval was sufficient to mediate the loss of tolerance to nuclear antigens, which had previously been attributed to a disrupted gene. These results demonstrate important epistatic modifiers of autoimmunity in 129 and C57BL/6 mouse strains, widely used in gene targeting. These background gene influences may account for some, or even all, of the autoimmune traits described in some gene-targeted models of SLE.

Fabrication and characterization of Y2O3 dispersion strengthened copper alloys

International Nuclear Information System (INIS)

Carro, G.; Muñoz, A.; Monge, M.A.; Savoini, B.; Pareja, R.; Ballesteros, C.; Adeva, P.

2014-01-01

Three copper base materials were fabricated following different routes: cast Cu–1 wt.%Y (C-Cu1Y) produced by vacuum induction melting, and Cu–1 wt.%Y (PM-Cu1Y) and Cu–1 wt.%Y 2 O 3 (PM-Cu1Y 2 O 3 ) both processed by a powder metallurgy route and sintering by hot isostatic pressing. PM-Cu1Y alloy was prepared by cryomilling and PM-Cu1Y 2 O 3 by conventional milling at room temperature. The materials were characterized by X-ray diffraction, optical and electron microscopy and microhardness measurements. C-Cu1Y presents a characteristic eutectic microstructure while PM-Cu1Y 2 O 3 exhibits a composite like microstructure. Electron microscopy analyses of as-HIP PM-Cu1Y revealed irregular decoration of yttrium-rich oxides at the grain boundaries and an inhomogeneous dispersion of polygonal shaped yttrium-rich oxides dispersed in the Cu matrix. Tensile tests performed on PM-Cu–1Y on the temperature range of 293–773 K have showed a decrease of the yield strength at temperatures higher than 473 K, and monotonically decrease of the ultimate tensile strength and maximum plastic strain on increasing temperature

Grain refinement of an AZ63B magnesium alloy by an Al-1C master alloy

Energy Technology Data Exchange (ETDEWEB)

Yichuan Pan; Xiangfa Liu; Hua Yang [The Key Lab. of Liquid Structure and Heredity of Materials, Shandong Univ., Jinan (China)

2005-12-01

In order to develop a refiner of Mg-Al alloys, an Al-1C (in wt.%) master alloy was synthesized using a casting method. The microstructure and grain-refining performance of the Al-1C master alloy were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and a grain-refining test. The microstructure of the Al-1C master alloy is composed of {alpha}-Al solid solution, Al{sub 4}C{sub 3} particles, and graphite phases. After grain refinement of AZ63B alloy by the Al-1C master alloy, the mean grain size reached a limit when 2 wt.% Al-C master alloy was added at 800 C and held for 20 min in the melt before casting. The minimum mean grain size is approximately 48 {mu}m at the one-half radius of the ingot and is about 17% of that of the unrefined alloy. The Al-1C master alloy results in better grain refinement than C{sub 2}Cl{sub 6} and MgCO{sub 3} carbon-containing refiners. (orig.)

Effects of Sm addition on microstructure and mechanical properties of a Mg-10Y alloy

Directory of Open Access Journals (Sweden)

Li Quanan

2014-01-01

Full Text Available To further increase the mechanical properties, 0.5wt.% Sm was introduced to a Mg-10Y alloy in this study. The effects of Sm addition on the microstructures and mechanical properties of the Mg-10Y alloy, especially the aged Mg-10Y alloy, were investigated. The microstructure observation and tensile tests were performed by using an optical microscopy, a scanning electron microscopy and a universal material testing machine, respectively. The phase analysis was performed using X-ray diffractometer. The results show that the 0.5wt.% Sm addition can not only promote the formation of fine and dispersed Mg24Y5 phases, but also improve their morphology and distribution; it also increases the thermal stability of Mg24Y5 phases. Sm addition is seen to increase the ultimate tensile strength of Mg-10Y alloy at elevated temperatures (200, 250, 300 and 350 ℃, while decrease the elongation. But the elongation is still up to 7.5% even at 350 ℃. In the range of 250 ℃ to 300℃, the ultimate tensile strength of the alloy reaches its maximum (with a range average of 235 MPa and is not sensitive to the temperature change, which is very useful to the application of heat-resistant magnesium alloys. Even at 350 ℃, the ultimate tensile strength of Mg-10Y-0.5Sm is still up to 155 MPa. Considering both of the ultimate tensile strength and elongation, the maximum application temperature of the Mg-10Y-0.5Sm alloy can be up to 300 ℃. The strengthening mechanisms of Mg-10Y-0.5Sm alloy are mainly attributed to dispersion strengthening of Mg24Y5 phase particles with a certain solubility of Sm and grain refinement strengthening of α-Mg matrix.

Hot tearing susceptibility of binary Mg–Y alloy castings

International Nuclear Information System (INIS)

Wang, Zhi; Huang, Yuanding; Srinivasan, Amirthalingam; Liu, Zheng; Beckmann, Felix; Kainer, Karl Ulrich; Hort, Norbert

2013-01-01

Highlights: ► Quantitatively and qualitatively assessing hot tearing susceptibility for different alloys. ► Monitoring the hot tearing propagation process. ► Detecting the hot tearing initiation/onset temperature. ► Recording the stress and strain evolution during the casting solidification and the subsequent cooling. - Abstract: The influence of Y content on the hot tearing susceptibility (HTS) of binary Mg–Y alloys has been predicted using thermodynamic calculations based on Clyne and Davies model. The calculated results are compared with experimental results determined using a constrained rod casting (CRC) apparatus with a load cell and data acquisition system. Both thermodynamic calculations and experimental measurements indicate that the hot tearing susceptibility as a function of Y content follows the “λ” shape. The experimental results show that HTS first increases with increase in Y content, reaches the maximum at about 0.9 wt.%Y and then decreases with further increase the Y content. The maximum susceptibility observed in Mg–0.9 wt.%Y alloy is attributed to its coarsened columnar microstructure, large solidification range and small amount of eutectic at the time of hot tearing. The initiation of hot cracks is monitored during CRC experiments. It corresponds to a drop in load increment on the force curves. The critical solid fractions at which the hot cracks are initiated are in the range from 0.9 to 0.99. It is also found that it decreases with increasing the content of Y. The hot cracks propagate along the dendritic or grain boundaries through the interdendritic separation or tearing of interconnected dendrites. Some of the formed cracks are possible to be healed by the subsequent refilling of the remained liquids

Diffusion of hydrogen in Pd-(Ce, Y, B) alloys

International Nuclear Information System (INIS)

Sakamoto, Y.; Kaneko, H.; Tsukahara, T.; Hirata, S.

1987-01-01

The study has been carried out to determine the diffusivity of hydrogen in Pd alloys containing Ce, Y and B in atom fractions up to θ/sub μ/ = 0.1 by an electrochemical permeation method, and to examine the lattice dilation effect on the diffusivity in these alloys. Ce and Y have been chosen because the solid solubility of both in Pd is about 13 at% in spite of the very large atomic size-factor difference between Pd and the solutes, and thus the expansion of the Pd lattice by Ce and Y is much larger than by Ag. Furthermore, it is of interest that the partial enthalpy of the dissolved hydrogen at infinite dilution ΔH 0 /sub H/ for Ce and Y is much smaller than for Pd. On the other hand, B atom also expands the Pd lattice in a way similar to Y, and sometimes B atoms may dissolve in the octahedral interstitial sites in the same way as hydrogen atoms

Correlation between stresses and adhesion of oxide scales on Si and Ti containing NiCrAlY alloys

International Nuclear Information System (INIS)

Vosberg, V.; Quadakkers, W.J.; Schubert, F.; Nickel, H.

1998-09-01

The relation between mechanical stresses and the adhesion of alumina scales on Si- and Ti-containing NiCrAlY alloys has been investigated. Therefore the Si and Ti contents in model alloys with the base composition Ni-20Cr-10Al-Y, which were cast to achieve high purity, were varied from 0 to 2 m/0 . These solid samples were subjected to cyclic oxidation in the temperature range from 950 to 1100 C. Growth and spallation of the oxide scale were observed by gravimetry. The stresses, present at ambient temperature, were periodically determined by X-ray stress evaluation. Using these results a reasoning of the mechanisms for stress relief and damage of the scale was carried out. The addition of Silicon as well as of titanium has an evident influence on phase composition of Ni-20Cr-10Al-Y type alloys. Due to the variation of phase stability regions the thermal expansion is affected by these additions in the range from 950 to 1100 C. The expansion is enlarged by the addition of Si and lowered with increasing Ti content. (orig.)

The Effect of Deep Cryogenic Treatment on the Corrosion Behavior of Mg-7Y-1.5Nd Magnesium Alloy

Directory of Open Access Journals (Sweden)

Quantong Jiang

2017-10-01

Full Text Available The effect of quenching on the corrosion resistance of Mg-7Y-1.5Nd alloy was investigated. The as-cast alloy was homogenized at 535 °C for 24 h, followed by quenching in air, water, and liquid nitrogen. Then, all of the samples were peak-aged at 225 °C for 14 h. The microstructures were studied by scanning electron microscopy, energy-dispersive spectrometry, and X-ray diffraction. Corrosion behavior was analyzed by using weight loss rate and gas collection. Electrochemical characterizations revealed that the T4-deep cryogenic sample displayed the strongest corrosion resistance among all of the samples. A new square phase was discovered in the microstructure of the T6-deep cryogenic sample; this phase was hugely responsible for the corrosion property. Cryogenic treatment significantly improved the corrosion resistance of Mg-7Y-1.5Nd alloy.

Laser cladding Ni-base composite coating on titanium alloy with pre-placed B4C+NiCoCrAlY

International Nuclear Information System (INIS)

Qingwu Meng; Lin Geng; Zhenzhu Zheng

2005-01-01

Using a CO 2 laser, a process of cladding Ni-base composite coating on Ti6Al4V with pre-placed B 4 C and NiCoCrAlY was studied. A good metallurgical bonding coating without cracks and pores was obtained in reasonable ratio of components and low energy laser process. Morphology and microstructure of the coating were analyzed with OM, XRD, SEM and EDS. It is certain that there was a reaction between B 4 C and Ti during in-situ producing TiB 2 and TiC. The Ni-base composite coating is strengthened with TiB 2 and TiC reinforcement phases. Vickers hardness tester measured that the average microhardness of the coating is HV1200 and it is 3.5 times of the Ti6Al4V substrate. The high hard coating containing several reinforcement phases greatly enhances wear resistance of titanium alloy. (orig.)

Surface morphology of scale on FeCrAl (Pd, Pt, Y) alloys

International Nuclear Information System (INIS)

Amano, T.; Takezawa, Y.; Shiino, A.; Shishido, T.

2008-01-01

The high temperature oxidation behavior of Fe-20Cr-4Al, floating zone refined (FZ) Fe-20Cr-4Al, Fe-20Cr-4Al-0.5Pd, Fe-20Cr-4Al-0.5Pt and Fe-20Cr-4Al-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys was studied in oxygen for 0.6-18 ks at 1273-1673 K by mass gain measurements, X-ray diffraction and scanning electron microscopy. The mass gains of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys showed almost the same values. Those of FeCrAl-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys decreased with increasing yttrium of up to 0.1% followed by an increase with the yttrium content after oxidation for 18 ks at 1473 K. Needle-like oxide particles were partially observed on FeCrAl alloy after oxidation for 7.2 ks at 1273 K. These oxide particles decreased in size with increasing oxidation time of more than 7.2 ks at 1473 K, and then disappeared after oxidation for 7.2 ks at 1573 K. It is suggested that a new oxide develops at the oxygen/scale interface. The scale surface of FeCrAl alloy showed a wavy morphology after oxidation for 7.2 ks at 1273 K which then changed to planar morphology after an oxidation time of more than 7.2 ks at 1573 K. On the other hand, the scale surfaces of other alloys were planar after all oxidation conditions in this study. The scale surfaces of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys were rough, however, those of FeCrAl-(0.1, 0.2, 0.5)Y alloys were smooth. The oxide scales formed on FeCrAl-(0.1, 0.2, 0.5)Y alloys were found to be α-Al 2 O 3 with small amounts of Y 3 Al 5 O 12 , and those of the other alloys were only α-Al 2 O 3

Effect of isothermal aging on the microstructure and properties of as-cast Mg-Gd-Y-Zr alloy

Energy Technology Data Exchange (ETDEWEB)

Liang Shuquan [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Guan Dikai, E-mail: gdk199@126.com [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Tan Xiaoping; Chen Liang; Tang Yan [School of Material Science and Engineering, Central South University, Changsha 410083 (China)

2011-01-25

Research highlights: {yields} The improvement of the hardness of the peak-aged alloys at 200 deg. C, 225 deg. C and 250 deg. C is mainly ascribed to the presence of the {beta}' phase. {yields} The alloy peak-aged at 200 deg. C displays the highest hardness owing to the existence of a great many {beta}' precipitates with a quite small size and uniform distribution in the matrix. {yields} The corrosion rates of the peak-aged samples increase as the isothermal aging temperature rise. The {beta}' precipitates are larger and appear to be more active as galvanic cathodes for the alloy peak-aged at the higher aging temperatures. {yields} Therefore, in our paper, optimal mechanical properties and good corrosion resistance in 5% NaCl solutions are obtained simultaneously when the alloy is aged at 200 deg. C for 120 h. - Abstract: The microstructure of Mg-7Gd-3Y-0.4Zr (wt.%) alloy during isothermal aging at 200 deg. C, 225 deg. C and 250 deg. C was investigated using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction. The mechanical properties of the peak-aged materials were evaluated by using Vickers hardness values, and their corrosion resistance was studied by using immersion tests, salt spray tests and electrochemical measurements in 5% NaCl solutions (wt.%). The results show that owing to the existence of a great many {beta}' precipitates with a quite small size and uniform distribution in the matrix, optimal mechanical properties and good corrosion resistance in 5% NaCl solutions are obtained when the alloy is aged at 200 deg. C for 120 h. The potentiodynamic polarization curves show that the corrosion current densities of the cathodic hydrogen evolution on the alloy peak-aged at 200 deg. C is lower than those for specimens of the alloy aged at 225 deg. C and 250 deg. C, which agrees fairly well with the microstructures of the alloys.

Direct observation of dislocation dissociation and Suzuki segregation in a Mg–Zn–Y alloy by aberration-corrected scanning transmission electron microscopy

International Nuclear Information System (INIS)

Yang Zhiqing; Chisholm, Matthew F.; Duscher, Gerd; Ma Xiuliang; Pennycook, Stephen J.

2013-01-01

Crystal defects in a plastically deformed Mg–Zn–Y alloy have been studied on the atomic scale using aberration-corrected scanning transmission electron microscopy, providing important structural data for understanding the material’s deformation behavior and strengthening mechanisms. Atomic scale structures of deformation stacking faults resulting from dissociation of different types of dislocations have been characterized experimentally, and modeled. Suzuki segregation of Zn and Y along stacking faults formed through dislocation dissociation during plastic deformation at 300 °C is confirmed experimentally on the atomic level. The stacking fault energy of the Mg–Zn–Y alloy is evaluated to be in the range of 4.0–10.3 mJ m −2 . The newly formed nanometer-wide stacking faults with their Zn/Y segregation in Mg grains play an important role in the superior strength of this alloy at elevated temperatures.

Crevice corrosion propagation on alloy 625 and alloy C276 in natural seawater

International Nuclear Information System (INIS)

McCafferty, E.; Bogar, F.D.; Thomas, E.D. II; Creegan, C.A.; Lucas, K.E.; Kaznoff, A.I.

1997-01-01

Chemical composition of the aqueous solution within crevices on two different Ni-Cr-Mo-Fe alloys immersed in natural seawater was determined using a semiquantitative thin-layer chromatographic method. Active crevices were found to contain concentrated amounts of dissolved Ni 2+ , Cr 3+ , Mo 3+ , and Fe 2+ ions. Propagation of crevice corrosion for the two alloys was determined from anodic polarization curves in model crevice solutions based upon stoichiometric dissolution or selective dissolution of alloy components. Both alloys 625 (UNS N06625) and C276 (UNS N10276) underwent crevice corrosion in the model crevice electrolytes. For the model crevice solution based upon selective dissolution of alloy constituents, the anodic dissolution rate for alloy 625 was higher than that for alloy C276. This trend was reversed for the model crevice solution based upon uniform dissolution of alloy constituents

Effect of Sr addition on microstructure and elevated temperature mechanical properties of Mg–3Zn–1Y alloy

Energy Technology Data Exchange (ETDEWEB)

Liu, Junwei [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Peng, Xiaodong, E-mail: pxd@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing 400044 (China); Li, Mengluan; Wei, Guobing [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Xie, Weidong [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing 400044 (China); Yang, Yan [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China)

2016-02-08

The effects of Sr addition on the microstructure and elevated temperature mechanical behavior of Mg–3Zn–1Y alloys have been investigated in this research. The results show that α-Mg, W-phase and S-phase are found in the Sr-containing alloys. The S-phase has a higher thermal stability than W-phase, which significantly improves the elevated temperature mechanical properties of the alloy. To further confirm the crystal structure of the S-phase, high resolution transmission electron microscopy analysis was performed and the phase was confirmed to be Mg{sub 6}Zn{sub 2}Sr{sub 1}. With increasing content of Sr, the elevated temperature mechanical properties of the Mg–3Zn–1Y are improved. When the Sr content reached to 0.9 wt%, the alloy shows a much higher ultimate tensile strength of 204 MPa and yield strength of 171 MPa at 250 °C.

Lattice vibrations study of Ga{sub 1-x}In{sub x}As{sub y}Sb{sub 1-y} quaternary alloys with low (In, As) content grown by liquid phase epitaxy

Energy Technology Data Exchange (ETDEWEB)

Olvera-Herandez, J [Centro de Investigacion en Dispositivos Semiconductores (CIDS), BUAP, Puebla, Pue. 72570 (Mexico); Olvera-Cervantes, J [Centro de Investigacion en Dispositivos Semiconductores (CIDS), BUAP, Puebla, Pue. 72570 (Mexico); Rojas-Lopez, M [Centro de Investigacion en BiotecnologIa Aplicada (CIBA), IPN, Tlaxcala, Tlax. 72160 (Mexico); Navarro-Contreras, H [Instituto de Investigacion en Comunicacion Optica (IICO), UASLP, 78100, San Luis PotosI, S.L.P. (Mexico); Vidal, M A [Instituto de Investigacion en Comunicacion Optica (IICO), UASLP, 78100, San Luis PotosI, S.L.P. (Mexico); Anda, F de [Instituto de Investigacion en Comunicacion Optica (IICO), UASLP, 78100, San Luis PotosI, S.L.P. (Mexico)

2006-01-01

Raman scattering spectroscopy was used to measure and analyze the lattice vibrations in some quaternary Ga{sub 1-x}In{sub x}As{sub y}Sb{sub 1-y} alloys with low (In, As) contents (0.03 y< 0.10). The layers were grown by liquid phase epitaxy on (001) GaSb substrates at 540{sup 0}C. High Resolution X-Ray Diffraction results showed profiles associated with a quaternary layer lattice matched to the GaSb substrate as obtained from the (004) reflection. The experimental diffractograms were simulated to estimate alloy composition, thickness and lattice mismatch of the layer. Raman scattering results show phonon frequencies associated to the TO and LO GaAs-like modes as well as GaSb + InAs-like mode, which are characteristic of this quaternary alloy. The As content dependence of the phonon frequency measured in this alloy for low (In, As) contents agree well with the modified Random-Element Isodisplacement (REI) model and also with other available experimental reports. This method can also be used to estimate alloy compositions for this kind of quaternary alloys.

Magnetic behavior of the alloys (Ce{sub 1-x}Y{sub x}){sub 2}PdSi{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mallik, R [Tata Inst. of Fundamental Res., Colaba, Mumbai (India); Sampathkumaran, E V [Tata Inst. of Fundamental Res., Colaba, Mumbai (India)

1996-11-01

The results of X-ray diffraction (Cu K{sub {alpha}}), electrical resistivity ({rho}), heat capacity (C) and magnetic susceptibility ({chi}) measurements are reported for a new pseudoternary solid solution, (Ce{sub 1-x}Y{sub x}){sub 2}PdSi{sub 3} (x=0.0, 0.2, 0.5, 0.8, 1.0). The X-ray diffraction patterns indicate that single phase alloys can be formed in a derived version of the AlB{sub 2}-type hexagonal structure for x{>=}0.2, while for x=0.0, apparently there is an additional weak phase. In the case of the alloy Ce{sub 2}PdSi{sub 3}, the majority of Ce ions do not exhibit magnetic ordering down to 1.4 K, though magnetic ordering at 7 K from one of the two crystallographically inequivalent sites cannot be ruled out. For other compositions, no magnetic ordering is observed above 1.4 K. The Kondo effect is operative in all these alloys, with the strength of the Kondo effect increasing with the compression of the lattice by the gradual replacement of Ce by Y. The C/T exhibits a low temperature enhancement in all Ce containing alloys. (orig.).

Effects of Ti addition and heat treatments on mechanical and electrical properties of Cu-Ni-Si alloys

Science.gov (United States)

Kim, Hyung Giun; Lee, Taeg Woo; Kim, Sang Min; Han, Seung Zeon; Euh, Kwangjun; Kim, Won Yong; Lim, Sung Hwan

2013-01-01

The mechanical and electrical properties of Cu-5.98Ni-1.43Si and Cu-5.98Ni-1.29Si-0.24Ti alloys under heat treatment at 400 and 500 °C after hot- and cold-rolling were investigated, and a microstructural analysis using transmission electron microscopy was performed. Cu-5.98Ni-1.29Si-0.24Ti alloy displayed the combined Vickers hardness/electrical conductivity value of 315.9 Hv/57.1%IACS. This was attributed to a decrease of the solution solubility of Ni and Si in the Cu matrix by the formation of smaller and denser δ-Ni2Si precipitates. Meanwhile, the alloyed Ti was detected in the coarse Ni-Si-Ti phase particles, along with other large Ni-Si phase particles, in Cu-5.98Ni-1.29Si-0.24Ti.

Microstructural evolution during dry wear test in magnesium and Mg-Y alloy

Energy Technology Data Exchange (ETDEWEB)

Somekawa, Hidetoshi, E-mail: SOMEKAWA.Hidetoshi@nims.go.jp [Research Center for Strategic Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Maeda, Shunsuke; Hirayama, Tomoko; Matsuoka, Takashi [Department of Mechanical Engineering, Doshisha University, 1-3 Miyakodani, Tatara, Kyotanabe 610-0321 (Japan); Inoue, Tadanobu [Research Center for Strategic Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Mukai, Toshiji [Department of Mechanical Engineering, Kobe University, 1-1 Rokkodai, Kobe, 657-8501 (Japan)

2013-01-20

The friction and wear properties of pure magnesium and the Mg-Y alloy were investigated using the pin-on-disk configuration. The friction and wear resistance of the Mg-Y alloy was superior to those of pure magnesium. The wear mechanism was abrasion under all the conditions. The deformed microstructural evolutions near the surface region were observed by transmission electron microscopy and electron backscatter diffraction. The stress and strain states were also evaluated by finite element analysis (FEA). The deformed microstructures of both alloys consisted of the {l_brace}10-12{r_brace} twinning formation and the FEA results showed the occurrence of plastic deformation even at the beginning of the test. The formation of low angle grain boundaries was also confirmed with an increase in the applied load in the Mg-Y alloy. On the other hand, grain refinement due to dynamic recrystallization was observed in pure magnesium as the wear test progressed. The different microstructures resulted from difference in the surface temperature during the wear test, which was estimated to be around 393 K and 363 K for pure magnesium and the Mg-Y alloy, respectively. The high increment temperature in the fine-grained alloys brought about the occurrence of grain boundary sliding, i.e., material softening, which led to a decrease in the friction and wear properties. The present results indicated that one of the methods for enhancing the friction and wear properties is to increase the dynamic recrystallization temperature.

Mode of carbide TiC-ZrC alloy fracture at various temperatures

Energy Technology Data Exchange (ETDEWEB)

Paderno, V.N.; Lesnaya, M.I.; Martynenko, A.N.; Chugunova, S.I. (AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya; Khersonskij Gosudarstvennyj Pedagogicheskij Inst. (Ukrainian SSR))

1983-05-01

Bending strength is studied for mutual TiC-ZrC alloys within a temperature range of 20-600 deg C. Structure of the material failure surface is studied from replicas by scanning and transmission electron microscopy. The data obtained are compared with concentration dependences of some physical properties of these alloys. Bending strength is shown to be minimum for the alloy with 40 mol % of zirconium carbide. It is stated that within the temperature range under study the carbide alloys undergo macroscopic brittle failure. The materials are characterized by a mixed type of failure with transcrystalline failure somewhat prevailing.

Mode of carbide TiC-ZrC alloy fracture at various temperatures

International Nuclear Information System (INIS)

Paderno, V.N.; Lesnaya, M.I.; Martynenko, A.N.; Chugunova, S.I.

1983-01-01

Bending strength is studied for mutual TiC-ZrC alloys within a temperature range of 20-600 deg C. Structure of the material failure surface is studied from replicas by scanning and transmission electron microscopy. The data obtained are compared with concentration dependences of some physical properties of these alloys. Bending strength is shown to be minimum for the alloy with 40 mol % of zirconium carbide. It is stated that within the temperature range under study the carbide alloys undergo macroscopic brittle failure. The materials are characterized by a mixed type of failure with transcrystalline failure somewhat prevailing

Evaluation of defect formation in helium irradiated Y2O3 doped W-Ti alloys by positron annihilation and nanoindentation

Science.gov (United States)

Richter, Asta; Anwand, Wolfgang; Chen, Chun-Liang; Böttger, Roman

2017-10-01

Helium implanted tungsten-titanium ODS alloys are investigated using positron annihilation spectroscopy and nanoindentation. Titanium reduces the brittleness of the tungsten alloy, which is manufactured by mechanical alloying. The addition of Y2O3 nanoparticles increases the mechanical properties at elevated temperature and enhances irradiation resistance. Helium ion implantation was applied to simulate irradiation effects on these materials. The irradiation was performed using a 500 kV He ion implanter at fluences around 5 × 1015 cm-2 for a series of samples both at room temperature and at 600 °C. The microstructure and mechanical properties of the pristine and irradiated W-Ti-ODS alloy are compared with respect to the titanium and Y2O3 content. Radiation damage is studied by positron annihilation spectroscopy analyzing the lifetime and the Doppler broadening. Three types of helium-vacancy defects were detected after helium irradiation in the W-Ti-ODS alloy: small defects with high helium-to-vacancy ratio (low S parameter) for room temperature irradiation, larger open volume defects with low helium-to-vacancy ratio (high S parameter) at the surface and He-vacancy complexes pinned at nanoparticles deeper in the material for implantation at 600 °C. Defect induced hardness was studied by nanoindentation. A drastic hardness increase is observed after He ion irradiation both for room temperature and elevated irradiation temperature of 600 °C. The Ti alloyed tungsten-ODS is more affected by the hardness increase after irradiation compared to the pure W-ODS alloy.

Correlative change of corrosion behavior with the microstructure of AZ91 Mg alloy modified with Y additions

International Nuclear Information System (INIS)

Jia, Ruiling; Zhang, Ming; Zhang, Lina; Zhang, Wei; Guo, Feng

2015-01-01

Highlights: • The effect of Y addition into the AZ91 Mg alloys was investigated. • Initial stage of corrosion was studied by in-situ 3D digital microscopy observation. • The potential difference was investigated by Kelvin probe force microscopy. • The effect of Y addition on the corrosion mechanisms of AZ91 alloy was studied. - Abstract: Microstructure characterization of the AZ91 magnesium alloys with or without rare earth element yttrium (Y) has been revealed by SEM, EDS and EPMA. Some Y-rich phases can be found in the magnesium alloys with Y additions. The fraction of β-Mg 17 Al 12 phase obvious decreases and turns into granular distribution with the increase of Y addition instead of original wet distribution along grain boundaries. The results of the potentiodynamic polarization tests show that the corrosion resistance of AZ91 alloy is improved with appropriate Y additions. But an in-situ observation of 3D digital microscopy for the initial stage of corrosion of the magnesium alloy with 0.9%Y addition shows that Y-rich phases act as cathodic effect and the α phases in the vicinity of them acting as anode are corroded. So the additions of Y have a beneficial effect that can depress the overall corrosion of AZ91 alloy, whereas its harmful effect is related to Y-rich phases because they present the highest Volta potential difference from the adjacent matrix and they can drive galvanic corrosion

Correlative change of corrosion behavior with the microstructure of AZ91 Mg alloy modified with Y additions

Energy Technology Data Exchange (ETDEWEB)

Jia, Ruiling, E-mail: jrl014014@163.com [College of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051 (China); Zhang, Ming; Zhang, Lina [College of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051 (China); Zhang, Wei [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China); Guo, Feng [College of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051 (China)

2015-06-15

Highlights: • The effect of Y addition into the AZ91 Mg alloys was investigated. • Initial stage of corrosion was studied by in-situ 3D digital microscopy observation. • The potential difference was investigated by Kelvin probe force microscopy. • The effect of Y addition on the corrosion mechanisms of AZ91 alloy was studied. - Abstract: Microstructure characterization of the AZ91 magnesium alloys with or without rare earth element yttrium (Y) has been revealed by SEM, EDS and EPMA. Some Y-rich phases can be found in the magnesium alloys with Y additions. The fraction of β-Mg{sub 17}Al{sub 12} phase obvious decreases and turns into granular distribution with the increase of Y addition instead of original wet distribution along grain boundaries. The results of the potentiodynamic polarization tests show that the corrosion resistance of AZ91 alloy is improved with appropriate Y additions. But an in-situ observation of 3D digital microscopy for the initial stage of corrosion of the magnesium alloy with 0.9%Y addition shows that Y-rich phases act as cathodic effect and the α phases in the vicinity of them acting as anode are corroded. So the additions of Y have a beneficial effect that can depress the overall corrosion of AZ91 alloy, whereas its harmful effect is related to Y-rich phases because they present the highest Volta potential difference from the adjacent matrix and they can drive galvanic corrosion.

Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

Science.gov (United States)

Pang, Q.; Hu, Z. L.; Wu, G. H.

2016-12-01

Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

Microstructure, corrosion resistance and cytocompatibility of Mg-5Y-4Rare Earth-0.5Zr (WE54) alloy

Energy Technology Data Exchange (ETDEWEB)

Smola, Bohumil, E-mail: bohumil.smola@mff.cuni.cz [Charles University Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Joska, Ludek [Institute of Chemical Technology Prague, Faculty of Chemical Technology, Technicka 5, 166 28 Praha 6 (Czech Republic); Brezina, Vitezslav [University of South Bohemia, Institute of Physical Biology, Zamek 136, 373 33 Nove Hrady (Czech Republic); Stulikova, Ivana [Charles University Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Hnilica, Frantisek [Czech Technical University in Prague, Faculty of Mechanical Engineering, Karlovo namesti 13, 121 35 Praha 2 (Czech Republic)

2012-05-01

Conventionally cast Mg-5Y-4Rare Earth-0.5Zr alloy (WE54) was solution treated (525 Degree-Sign C/8 h - T4) and one part subsequently aged (200 Degree-Sign C/16 h - T6). Powder from the cast WE54 alloy prepared by gas atomizing was consolidated by extrusion at 250 Degree-Sign C or 400 Degree-Sign C. Dense triangular arrangement of prismatic plates of transient D0{sub 19} and C-base centered orthorhombic phases precipitated in the {alpha}-Mg matrix during the T6 treatment. Both alloys prepared by powder metallurgy exhibit similar microstructure consisting of {approx} 4-6 {mu}m {alpha}-Mg matrix fibers surrounded by particles of the equilibrium Mg{sub 5}(Y, Nd) phase and of oxides. Open circuit potential and polarization resistance in the isotonic saline (9 g/l NaCl/H{sub 2}O) were monitored for 24 h. The corrosion rate of the T4 and T6 treated alloys was about 80 times lower than that of commercial Mg. Both alloys prepared by powder metallurgy exhibited approximately 8 times higher corrosion resistance than commercial Mg. The human MG-63 osteoblast-like cells spreading and division in the extracts (0.28 g in 28 ml of EMEM) of all 4 alloys were monitored by cinemicrography for 24 h. The MG-63 cells proliferate without cytotoxicity in all extracts. - Highlights: Black-Right-Pointing-Pointer T6 treated WE54 alloy exhibit dense triangular arrangement of {beta} Double-Prime and {beta} Prime phase prismatic plates. Black-Right-Pointing-Pointer Microstructure of PM prepared WE54 alloy consists of {alpha}-Mg phase cells surrounded by {beta} phase particles. Black-Right-Pointing-Pointer PM produced WE54 corroded 10 times faster in physiological solution thanT4 and T6 treated WE54. Black-Right-Pointing-Pointer MG63 cell spreading in EMEM extracts of PM prepared WE54 is comparable to that in control EMEM. Black-Right-Pointing-Pointer Cell mitosis is enhanced in PM WE54 extracts compared to the control and extracts of T4 and T6 WE54.

In vitro corrosion of Mg–1.21Li–1.12Ca–1Y alloy

Directory of Open Access Journals (Sweden)

Rongchang Zeng

2014-10-01

Full Text Available The influence of the microstructure on mechanical properties and corrosion behavior of the Mg–1.21Li–1.12Ca–1Y alloy was investigated using OM, SEM, XRD, EPMA, EDS, tensile tests and corrosion measurements. The results demonstrated that the microstructure of the Mg–1.21Li–1.12Ca–1Y alloy was characterized by α-Mg substrate and intermetallic compounds Mg2Ca and Mg24Y5. Most of the fine Mg2Ca particles for the as-cast alloy were distributed along the grain boundaries, while for the as-extruded along the extrusion direction. The Mg24Y5 particles with a larger size than the Mg2Ca particles were positioned inside the grains. The mechanical properties of Mg–1.21Li–1.12Ca–1Y alloy were improved by the grain refinement and dispersion strengthening. Corrosion pits initiated at the α-Mg matrix neighboring the Mg2Ca particles and subsequently the alloy exhibited general corrosion and filiform corrosion as the corrosion product layer of Mg(OH2 and MgCO3 became compact and thick.

In-situ studies of the TGO growth stresses and the martensitic transformation in the B2 phase in commercial Pt-modified NiAl and NiCoCrAlY bond coat alloys

Energy Technology Data Exchange (ETDEWEB)

Hovis, D.; Hu, L.; Reddy, A.; Heuer, A.H. [Dept. of Materials Science and Engineering, Case Western Reserve Univ., Cleveland, OH (United States); Paulikas, A.P.; Veal, B.W. [Materials Science Div., Argonne National Lab., Argonne, IL (United States)

2007-12-15

Oxide growth stresses were measured in situ at 1100 C on commercial Pt-modified NiAl and NiCoCrAlY bond coat alloys using synchrotron X-rays. Measurements were taken on samples that had no preoxidation, as well as on samples that had experienced 24 one-hour thermal exposures at 1150 C, a condition known to induce rumpling in the Pt-modified NiAl alloy, but not in the NiCoCrAlY alloy. The NiCoCrAlY alloy showed continuous stress relaxation under all conditions, whereas the Pt-modified NiAl alloys would typically stabilize at a fixed (often non-zero) stress suggesting a higher creep strength in the 'Thermally Grown Oxide' on the latter alloy, though the precise behavior was dependent on initial surface preparation. The formation of martensite in the Pt-modified NiAl alloys was also observed upon cooling and occurred at temperatures below 200 C for all of the samples observed. Based on existing models, this M{sub s} temperature is too low to account for the rumpling observed in these alloys. (orig.)

Sulfidation behavior of Fe20Cr alloys

International Nuclear Information System (INIS)

Pillis, Marina Fuser

2001-01-01

Alloys for use in high temperature environments rely on the formation of an oxide layer for their protection. Normally, these protective oxides are Cr 2 O 3 , Al 2 O 3 and, some times, SiO 2 . Many industrial gaseous environments contain sulfur. Sulfides, formed in the presence of sulfur are thermodynamically less stable, have lower melting points and deviate much more stoichiometrically, compared to the corresponding oxides. The mechanism of sulfidation of various metals is as yet not clear, in spite of the concerted efforts during the last decade. To help address this situation, the sulfidation behavior of Fe20Cr has been studied as a function of compositional modifications and surface state of the alloy. The alloys Fe20Cr, Fe20Cr0.7Y, Fe20Cr5Al and Fe20Cr5Al0.6Y were prepared and three sets of sulfidation tests were carried out. In the first set, the alloys were sulfidized at 700 deg C and 800 deg C for 10h. In the second set, the alloys were pre-oxidized at 1000 deg C and then sulfidized at 800 deg C for up to 45h. In the third set of tests, the initial stages of sulfidation of the alloys was studied. All the tests were carried out in a thermobalance, in flowing H 2 /2%H 2 S, and the sulfidation behavior determined as mass change per unit area. Scanning electron microscopy coupled to energy dispersive spectroscopy and X-ray diffraction analysis were used to characterize the reaction products. The addition of Y and Al increased sulfidation resistance of Fe20Cr. The addition of Y altered the species that diffused predominantly during sulfide growth. It changed from predominant cationic diffusion to predominant anionic diffusion. The addition of Al caused an even greater increase in sulfidation resistance of Fe20Cr, with the parabolic rate constant decreasing by three orders of magnitude. Y addition to the FeCrAl alloy did not cause any appreciable alteration in sulfidation resistance. Pre-oxidation of the FeCrAl and FeCrAlY alloys resulted in an extended

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.

A Critical Review of High Entropy Alloys and Related Concepts (Postprint)

Science.gov (United States)

2016-10-21

1301e1305. [306] C. Huang, Y.Z. Zhang, R. Vilar, J.Y. Shen, Dry sliding wear behavior of laser clad TiVCrAlSi high entropy alloy coatings on Ti-6Al...Res. 652e654 (2013) 1115e1118. [313] C. Huang, Y. Zhang, J. Shen, R. Vilar, Thermal stability and oxidation resis- tance of laser clad TiVCrAlSi high...Section 7.1.3). Finally, it is not always true that SS alloys are ductile. Well-known examples include b- titanium alloys, a- titanium alloys with small

Investigation of the radioecology of iodine 129

International Nuclear Information System (INIS)

Schuettelkopf, H.

1979-01-01

Very sensitive analytical methods for I-129 were developed for different sample materials. - The behaviour of I-129 in the Karlsruhe reprocessing plant and its release was completely investigated. - A longterm risk for the population caused by I-129 is not excpected. An existing environmental contamination with I-129 is reduced by a half-life of 0,3 y. The exposure of the population via the pasture-cow-milk path until now was overstimated at least by a factor 45. - In the environmental air of Kiel, Stade, Karlsruhe, Gundremmingen and Munich elemental iodine and iodine aerosols were measured. In the environmental air of Karlsruhe CH 3 127 I was determined. (orig./RW) [de

Thermophysical properties of Alloy 617 from 25 °C to 1000 °C

International Nuclear Information System (INIS)

Rabin, B.H.; Swank, W.D.; Wright, R.N.

2013-01-01

Highlights: • Thermophysical properties of Alloy 617 have been measured to 1000 °C. • Thermal conductivity at 600–850 °C is nonlinear due to Ni–Cr short-range ordering. • Four different heats and long-term aged material all exhibited similar properties. -- Abstract: Key thermophysical properties needed for the successful design and use of Alloy 617 in steam generator and heat exchanger applications have been measured experimentally, and results are compared with literature values and results obtained from some other commercial Ni–Cr alloys and model materials. Specifically, the thermal diffusivity, thermal expansion coefficient, and specific heat capacity have been measured for Alloy 617 over a range of temperatures, allowing calculation of thermal conductivity up to 1000 °C. It has been found that the thermal conductivity of Alloy 617 exhibits significant deviation from monotonic behavior in the temperature range from 600 °C to 850 °C, the temperatures of interest for most heat transfer applications. The non-linear behavior appears to result primarily from short-range order/disorder phenomena known to occur in the Ni–Cr system. Similar deviation from monotonic behavior was observed in the solid solution Ni–Cr-W Alloy 230, and lesser deviations were observed in iron based Alloy 800H and an austenitic stainless steel. Measured thermophysical property data are provided for four different heats of Alloy 617, and it is shown that property variations between the four different heats are not significant. Measurements were also obtained from Alloy 617 that was aged for up to 2000 h at 750 °C, and it was found that this aging treatment does not significantly influence the thermophysical properties

Crystallisation kinetics of amorphous Fe72.5-xCu1Nb4.5Si10+x+yB12-y alloy

International Nuclear Information System (INIS)

Miglierini, M.; Lipka, J.; Sitek, J.

1994-01-01

Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 and Fe 72.5-x Cu 1 Nb 4.5 Si 10+x+y B 12-y alloys are compared from the point of view of crystallisation behaviour and changes in the short-range order in the amorphous reminder. The increase in Nb to 4.5 at.% in the latter system slows down the formation of nanocrystals to approximately 40% even after 16 hours of anneal at 550 C for x = 0.5, y = 3. Segregation-induced changes in the short-range order are manifested via hyperfine field distributions corresponding to the amorphous reminder. (orig.)

Iodine-129 in rabbit thyroids near a nuclear fuel reprocessing plant in Idaho

International Nuclear Information System (INIS)

Fraley, L. Jr.; Bowman, G.C.; Markham, O.D.

1982-01-01

The 129 I/ 127 I atom ratios in rabbits collected on the INEL site were larger than ratios in rabbits from a control area. Maximum 129 I/ 127 I atom ratios (9.1 x 10 -4 ) occurred near the Idaho Chemical Processing Plant (ICPP). Based on rabbit thyroid concentrations, the 129 I appeared to be deposited primarily in the direction of the predominant winds from the ICPP, northeast and southwest. Dose rates from the 129 I to thyroids of INEL rabbits varied from 0.1 to 260 μGy/y (0.01 to 26 mrad/y). Iodine-129 atmospheric releases from the ICPP appeared to have increased the 129 I/ 127 I atom ratios on and near the INEL site. (author)

Fabrication and characterization of Y{sub 2}O{sub 3} dispersion strengthened copper alloys

Energy Technology Data Exchange (ETDEWEB)

Carro, G.; Muñoz, A. [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Savoini, B.; Pareja, R.; Ballesteros, C. [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Adeva, P. [Centro Nacional de Investigaciones Metalúrgicas, CSIC, Av. Gregorio del Amo, 8, 28040 Madrid (Spain)

2014-12-15

Three copper base materials were fabricated following different routes: cast Cu–1 wt.%Y (C-Cu1Y) produced by vacuum induction melting, and Cu–1 wt.%Y (PM-Cu1Y) and Cu–1 wt.%Y{sub 2}O{sub 3} (PM-Cu1Y{sub 2}O{sub 3}) both processed by a powder metallurgy route and sintering by hot isostatic pressing. PM-Cu1Y alloy was prepared by cryomilling and PM-Cu1Y{sub 2}O{sub 3} by conventional milling at room temperature. The materials were characterized by X-ray diffraction, optical and electron microscopy and microhardness measurements. C-Cu1Y presents a characteristic eutectic microstructure while PM-Cu1Y{sub 2}O{sub 3} exhibits a composite like microstructure. Electron microscopy analyses of as-HIP PM-Cu1Y revealed irregular decoration of yttrium-rich oxides at the grain boundaries and an inhomogeneous dispersion of polygonal shaped yttrium-rich oxides dispersed in the Cu matrix. Tensile tests performed on PM-Cu–1Y on the temperature range of 293–773 K have showed a decrease of the yield strength at temperatures higher than 473 K, and monotonically decrease of the ultimate tensile strength and maximum plastic strain on increasing temperature.

Control decisions for 3H, 14C, 85Kr, and 129I released from the commercial fuel cycle

International Nuclear Information System (INIS)

Thomas, T.R.; Brown, R.A.

1985-01-01

The effects of complete release of 3 H, 14 C, 85 Kr and 129 I from operating a 400-GWe fuel cycle for 100 years are shown. The postulated accrued health effects (HE) from 14 C and 129 I appear large; however, these numbers are insignificant when compared to the 176 billion cancer deaths that would occur from all causes in the 10,000-year reference period. The percent increase in global cancer deaths would be no greater than 5 x 10 -5 % for each of the radionuclides. Based on the 1980 inventory of each radionuclide in the environment, complete release for 100 years from a 400-GWe fuel cycle would not increase the 3 H or 14 C inventories, however, large increases in 85 Kr and 129 I inventories would occur. The effects, besides dose impacts, of large increases in inventory are unknown and serve only as warning flags that should be taken into consideration. Only 129 I releases from a fuel reprocessing plant would exceed the allowable maximum exposed individual dose limit and 85 Kr and 129 I would exceed the allowable release limit. The effects of controlled releases from commercial fuel reprocessing plants serving a 400-GWe fuel cycle for 100 years are also shown

Electron microscopy characterization of mechanically alloyed and hot consolidates Cu-Cr₃C₂ particles

Directory of Open Access Journals (Sweden)

López, M.

2005-08-01

Full Text Available Mechanically alloyed copper-ceramic composites have been obtained with the purpose of studying their use as copper-based material for electrical equipment. For high-temperature applications, dispersion-strengthened copper alloys are attractive due to their excellent combination of thermal and electrical conductivity, mechanical strength retention and microstructural stability. In this work, powder mixtures of pure copper with 2 vol % Cr₃C₂, milled during 4, 6, 10, 12 and 15 h in a high-energy planetary balls mill under argon atmosphere, were consolidated by hot isostatic pressing, applying a pressure of 100 MPa at 1073 K for two hours, to obtain materials with a fine microstructure. The Cu-Cr₃C₂ alloys were studied by scanning electron microscopy (SEM, electron microprobe (EPMA and transmission electron microscopy (TEM. Mechanical properties and electrical conductivity were also studied. The average tensile strength and electrical conductivity were found to be 500 MPa and 50 % IACS, respectively. The Cr₃C₂ ceramics show good stability during hot consolidation. Contributing to a further strengthening of the alloy during the hot consolidation, uniformly-distributed Fe-carbide particles of nanometric size precipitated in the copper matrix. Fe-Cr oxycarbides formed in the interphase between Cr₃C₂ particles and the copper matrix cause the low ductility of Cu-Cr₃C₂ alloys. Said particles are attributed to impurities/contamination generated from the milling process.

Se obtuvieron aleaciones compuestas de Cu-Cr₃C₂, aleadas mecánicamente, para estudiar futuras aplicaciones en componentes eléctricos. A altas temperaturas, las aleaciones de base cobre reforzadas por dispersión, son atractivas por su excelente conductividad térmica y eléctrica, propiedades mecánicas y estabilidad microstructural. En este estudio

Preparation and Properties of Mg-Cu-Y-Al bulk Amorphous Alloys

DEFF Research Database (Denmark)

Pryds, Nini; Eldrup, Morten Mostgaard; Ohnuma, M.

2000-01-01

Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial and tempo......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial...... temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg(60)CU(30)Y(10) specimen was determined experimentally by a combination of DSC data and temperature vs, time...

The electronic and optical properties of quaternary GaAs1-x-y N x Bi y alloy lattice-matched to GaAs: a first-principles study.

Science.gov (United States)

Ma, Xiaoyang; Li, Dechun; Zhao, Shengzhi; Li, Guiqiu; Yang, Kejian

2014-01-01

First-principles calculations based on density functional theory have been performed for the quaternary GaAs1-x-y N x Bi y alloy lattice-matched to GaAs. Using the state-of-the-art computational method with the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional, electronic, and optical properties were obtained, including band structures, density of states (DOSs), dielectric function, absorption coefficient, refractive index, energy loss function, and reflectivity. It is found that the lattice constant of GaAs1-x-y N x Bi y alloy with y/x =1.718 can match to GaAs. With the incorporation of N and Bi into GaAs, the band gap of GaAs1-x-y N x Bi y becomes small and remains direct. The calculated optical properties indicate that GaAs1-x-y N x Bi y has higher optical efficiency as it has less energy loss than GaAs. In addition, it is also found that the electronic and optical properties of GaAs1-x-y N x Bi y alloy can be further controlled by tuning the N and Bi compositions in this alloy. These results suggest promising applications of GaAs1-x-y N x Bi y quaternary alloys in optoelectronic devices.

Manufacturing and testing of self-passivating tungsten alloys of different composition

Directory of Open Access Journals (Sweden)

A. Calvo

2016-12-01

Bulk W-15Cr, W-10Cr-2Ti and W-12Cr-0.5Y alloys were manufactured by mechanical alloying followed by can encapsulation and HIP. This route resulted in fully dense materials with nano-structured grains. The ability of Ti and especially of Y to inhibit grain growth was observed in the W-10Cr-2Ti and W-12Cr-0.5Y alloys. Besides, Y formed Y-rich oxide nano-precipitates at the grain boundaries, and is thus expected to improve the mechanical behaviour of the Y-containing alloy. Isothermal oxidation tests at 800 ºC (1073K and oxidation tests under accident-like conditions revealed that the W-12Cr-0.5Y alloy exhibits the best oxidation behaviour of all alloys, especially in the accident-like scenario. Preliminary HHF tests performed at GLADIS indicated that the W-10Cr-2Ti alloy is able to withstand power densities of 2 MW/m2 without significant damage of the bulk structure. Thermo-shock tests at JUDITH-1 to simulate mitigated disruptions resulted in chipping of part of the surface of the as-HIPed W-10Cr-2Ti alloy. An additional thermal treatment at 1600 °C (1873K improves the thermo-shock resistance of the W-10Cr-2Ti alloy since only crack formation is observed.

Theory of Rare-Earth Alloys

DEFF Research Database (Denmark)

Lindgård, Per-Anker

1977-01-01

A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...

Effect of Ca and Y additions on oxidation behavior of magnesium alloys at high temperatures

Institute of Scientific and Technical Information of China (English)

FAN Jianfeng; YANG Changlin; XU Bingshe

2012-01-01

Oxidation and ignition of magnesium alloys at elevated temperature were successfully retarded by additions of Y and Ca.which could be melted at 1173 K in air without any protection.Thermogravimetric measurements in dry air revealed that the oxidation dynamics curves of Mg-2.5Ca alloy and Mg-3.5Y-0.79Ca alloy at high temperatures followed the parabolic-line law or the ubic-line law.X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis indicated that the oxide film on the surface of Mg-3.5Y-0.79Ca and Mg-2.5Ca alloys exhibited a duplex structure.which agreed with the results of thermodynamic analysis.By comparison,the ignition-proof effect of the combination addition of Y and Ca was better than that of the single addition of Ca.

Microstructure and property evaluation of high-pressure die-cast Mg–La–rare earth (Nd, Y or Gd) alloys

International Nuclear Information System (INIS)

Gavras, Serge; Easton, Mark A.; Gibson, Mark A.; Zhu, Suming; Nie, Jian-Feng

2014-01-01

Highlights: • Different rare earth elements have remarkably different effects on Mg castability. • For the addition of each RE element, the alloy castability follows a unique pattern. • The effects of RE elements on the castability can be modelled. - Abstract: Microstructure, castability and tensile properties were investigated in high-pressure die-cast Mg–La–Nd, Mg–La–Y and Mg–La–Gd alloy series, with a constant La concentration at approximately 2.5 wt.% and the concentrations of Nd, Y or Gd were varied. All three alloy series had a dendritic microstructure with a Mg–La-rich eutectic with increasing Nd, Y or Gd content and containing a Mg 12 RE intermetallic phase. The morphology of the eutectic at ternary alloying additions of equal to or less than 1.0 wt.% was lamellar but became increasingly divorced at higher ternary concentrations. This was however more obvious in Mg–La–Y and Mg–La–Gd than Mg–La–Nd alloys. The hot tearing susceptibility in all three alloy series increased markedly with even micro-alloying additions of Nd, Y or Gd, and began to decrease again in alloys with more than 0.5 wt.% Y or 1.0 wt.% Gd, but did not decrease significantly for Mg–La–Nd. A model using the temperature–fraction solid curves as input parameters was used to estimate hot tearing susceptibility for Mg–La–Nd alloys. Tensile testing at room temperature showed that Mg–La–Nd alloy series had higher 0.2% proof stress and lower elongation to failure than either the Mg–La–Y or the Mg–La–Gd alloy series for Nd concentrations greater than 1 wt.% due to a greater effectiveness of grain boundary reinforcement

Amorphization of C-implanted Fe(Cr) alloys

International Nuclear Information System (INIS)

Knapp, J.A.; Follstaedt, D.M.; Sorensen, N.R.; Pope, L.E.

1991-01-01

The amorphous phase formed by implanting C into Fe alloyed with Cr, which is a prototype for the amorphous phase formed by implanting C into stainless steels, is compared to that formed by implanting C and Ti into Fe and steels. The composition range of the phase has been examined; higher Cr and C concentrations are required than needed with Ti and C. The friction and wear benefits obtained by implanting stainless steels with C only do not persist for the long durations and high wear loads found with Ti and C. However, the amorphous Fe-Cr-C alloys exhibit good aqueous corrosion resistance. (orig.)

Solubility of tritium in Pd1-YAgY alloys (Y = 0.00, 0.10, 0.20, 0.30)

International Nuclear Information System (INIS)

Lasser, R.; Powell, G.L.

1988-01-01

Solubility measurements of tritium (T) in Pd 1-Y Ag Y alloys (Y = 0.00, 0.10, 0.20, 0.30) are reported in the temperature range of 250 K to 733 K, the pressure range below 3 bar, and the concentration range of 0.001 to 0.64 hydrogen to metal atom ratio. To study isotopic effects, the pressure-concentration-temperature relationships of the hydrogen isotopes protium (H) and deuterium (D) have been measured using the same samples and experimental setup and to temperatures as high as 1500 K using a different set up and samples. The experimental data are compared with values for H and D determined by other groups. In the case of T, most of the data presented have not been determined before. From these data the Sieverts' constants were calculated which show a strong temperature and isotope dependence. Analytical expressions, based on models that assume various degrees to which the hydrogen can perceive the alloy composition of individual sites in an alloy, are given for the Sieverts' constants that allow the calculation of the standard Gibbs free energies, enthalpies and entropies of H, D and T in these alloys

Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys; Influencia de um revestimento de niobio sobre a resistencia a sulfetacao das ligas FeCr e FeCrY

Energy Technology Data Exchange (ETDEWEB)

Geribola, Gulherme Altomari

2014-07-01

Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H{sub 2}/2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

United modification of Al-24Si alloy by Al-P and Al-Ti-C master alloys

Institute of Scientific and Technical Information of China (English)

韩延峰; 刘相法; 王海梅; 王振卿; 边秀房; 张均艳

2003-01-01

The modification effect of a new type of Al-P master alloy on Al-24Si alloys was investigated. It is foundthat excellent modification effect can be obtained by the addition of this new type of A1-P master alloy into Al-24Simelt and the average primary Si grain size is decreased below 47 μm from original 225 μm. It is also found that theTiC particles in the melt coming from Al8Ti2C can improve the modification effect of the Al-P master alloy. Whenthe content of TiC particles in the Al-24Si melt is 0.03 %, the improvement reaches the maximum and keeps steadywith increasing content of TiC particles. Modification effect occurs at 50 min after the addition of the Al-P master al-loy and TiC particles, and keeps stable with prolonging holding time.

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.

New look at magnetism in single-crystal Gd-Y alloys

International Nuclear Information System (INIS)

Ito, T.; Legvold, S.; Beaudry, B.J.

1981-01-01

Magnetic susceptibility, electrical resistivity, and specific-heat measurements have been made on a number of polycrystalline and single-crystal samples of Gd-rich Gd-Y alloys. It has been found (i) that samples with more than 30 at. % Y exhibit a helical structure phase; (ii) that samples between 10 and 30 at. % Y exhibit two different Curie-Weiss regimes leading to ''double'' ferromagnetism; and (iii) that samples with less than 10 at. % Y have Gd-like behavior

Size effect of primary Y{sub 2}O{sub 3} additions on the characteristics of the nanostructured ferritic ODS alloys: Comparing as-milled and as-milled/annealed alloys using S/TEM

Energy Technology Data Exchange (ETDEWEB)

Saber, Mostafa, E-mail: msaber@ncsu.edu; Xu, Weizong; Li, Lulu; Zhu, Yuntian; Koch, Carl C.; Scattergood, Ronald O.

2014-09-15

The need for providing S/TEM evidence to clarify the mechanisms of nano-scale precipitate formation was the motivation of this investigation. In this study, an Fe–14Cr–0.4Ti alloy was ball-milled with different amounts of Y{sub 2}O{sub 3} content up to 10 wt.%, and then annealed at temperatures up to 1100 °C. Micron-size Y{sub 2}O{sub 3} particles were substituted for the nano-size counterpart to elucidate the mechanism of oxide precipitate formation. The S/TEM studies revealed that the microstructure of the alloy with 10 wt.% yttria contained amorphous undissolved Y{sub 2}O{sub 3} after ball milling, while a small part of the initial oxide particles were dissolved into the solid solution. Consequently, when the amount of yttria was reduced to 1 wt.%, the amorphous phase of the yttria vanished and the whole content of Y{sub 2}O{sub 3} was dissolved into the BCC solid solution. Defect analysis of precipitates on the annealed samples via S/TEM and micro-hardness studies revealed that the use of micron-size primary oxide particles can produce nano-size precipitates, stable up to temperatures as high as 1100 °C, and uniformly distributed throughout the microstructure. This study indicates that the use of high energy ball milling along with micron-size primary oxide particles can lead to nanostructured ferritic ODS alloys without the use of nano-size primary oxide additions.

Ab-initio study of phase stability, elastic and thermodynamic properties of AlY alloy under pressure

Energy Technology Data Exchange (ETDEWEB)

Zhou, Dawei [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Su, Taichao [Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000 (China); Song, Haizhen; Lu, Cheng; Zhong, Zhiguo; Lu, Zhiwen [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Pu, Chunying, E-mail: puchunying@126.com [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China)

2015-11-05

Using the particle swarm optimization algorithm combined with first-principles methods, we explore the diagram of AlY alloy up to 250 GPa. It is found that AlDy phase, rather than the experimentally observed B2 phase, is the most stable structure at 0 K and 0–20 GPa. However, our results show that B2 phase can exist as a stable phase at 20–27.6 GPa. At higher pressure, four new high-pressure phases with Cmcm-I, Cmcm-II, I4/mmm and P4/nmm structure are identified for the first time. The hardness, elastic and thermodynamic properties of the newly found phases are investigated and compared with B2 phase. The calculated hardness of AlDy, Cmcm-I, Cmcm-II, I4/mmm and P4/nmm phases is in the range of 7–9 GPa, higher than that of B2 phase. In addition, it is found that AlDy phase is a brittle material at 0 GPa, which changes to a ductile material above 12 GPa. Except for AlDy phase, all the other AlY compounds exhibit completely ductile behavior under pressure. Compared with the other phases, B2 phase is found to have the best ductility and the largest elastic anisotropy over the whole pressure investigated. Moreover, all AlY intermetallics exhibit a nearly elastic isotropy in compressibility but a comparatively large elastic anisotropy in shear. The structural stability, electronic structure, bulk and shear modulus, Debye temperature as well as sound velocities of AlY alloy under pressure are also deeply discussed. - Graphical abstract: Pressure-induced phase transition of AlY alloy up to 250 GPa. - Highlights: • The diagram of AlY alloy was explored and four new stable phases were predicted. • B2 phase shows the largest ductility and elastic anisotropy among AlY alloys. • All AlY alloys exhibit ductile behavior except for AlDy phase under pressure. • All AlY alloys show strong isotropy in compressibility and anisotropy in shear.

Microstructure and Aging Behavior of Nonflammable AZ91D Mg Alloy

OpenAIRE

Seok Hong Min; Tae Kwon Ha

2014-01-01

Phase equilibria of AZ91D Mg alloys for nonflammable use, containing Ca and Y, were carried out by using FactSage® and FTLite database, which revealed that solid solution treatment could be performed at temperatures from 400 to 450oC. Solid solution treatment of AZ91D Mg alloy without Ca and Y was successfully conducted at 420oC and supersaturated microstructure with all beta phase resolved into matrix was obtained. In the case of AZ91D Mg alloy with some Ca and Y; howeve...

Effects of microRNA-129 and its target gene c-Fos on proliferation and apoptosis of hippocampal neurons in rats with epilepsy via the MAPK signaling pathway.

Science.gov (United States)

Wu, Dong-Mei; Zhang, Yu-Tong; Lu, Jun; Zheng, Yuan-Lin

2018-09-01

This study aims to investigate the effect of microRNA-129 (miR-129) on proliferation and apoptosis of hippocampal neurons in epilepsy rats by targeting c-Fos via the MAPK signaling pathway. Thirty rats were equally classified into a model group (successfully established as chronic epilepsy models) and a normal group. Expression of miR-129, c-Fos, bax, and MAPK was detected by RT-qPCR and Western blotting. Hippocampal neurons were assigned into normal, blank, negative control (NC), miR-129 mimic, miR-129 inhibitor, siRNA-c-Fos, miR-129 inhibitor+siRNA-c-Fos groups. The targeting relationship between miR-129 and c-Fos was predicted and verified by bioinformatics websites and dual-luciferase reporter gene assay. Cell proliferation after transfection was measured by MTT assay, and cell cycle and apoptosis by flow cytometry. c-Fos is a potential target gene of miR-129. Compared with the normal group, the other six groups showed a decreased miR-129 expression; increased expression of expression of c-Fos, Bax, and MAPK; decreased proliferation; accelerated apoptosis; more cells arrested in the G1 phase; and fewer cells arrested in the S phase. Compared with the blank and NC groups, the miR-129 mimic group and the siRNA-c-Fos group showed decreased expression of c-Fos, Bax, and MAPK, increased cells proliferation, and decreased cell apoptosis, fewer cells arrested in the G1 phase and more cells arrested in the S phase. However, the miR-129 inhibitor groups showed reverse consequences. This study suggests that miR-129 could inhibit the occurrence and development of epilepsy by repressing c-Fos expression through inhibiting the MAPK signaling pathway. © 2017 Wiley Periodicals, Inc.

Oxidation behavior of NiCoCrAlY coatings deposited by double-Glow plasma alloying

Science.gov (United States)

Cui, Shiyu; Miao, Qiang; Liang, Wenping; Li, Baiqiang

2018-01-01

The NiCoCrAlY coatings were deposited on the Inconel 718 alloy substrates by a novel method called double-glow plasma alloying (DG). The phases and microstructure of the coatings were investigated by X-ray diffraction analysis while their chemical composition was analyzed using scanning electron microscopy. The morphology of the NiCoCrAlY coatings was typical of coatings formed by DG, with their structure consisting of uniform submicron-sized grains. Further, the coatings showed high adhesion strength (critical load >46 N). In addition, the oxidation characteristics of the coatings and the substrate were examined at three different temperatures (850, 950, and 1050 °C) using a muffle furnace. The coatings showed a lower oxidation rate, which was approximately one-tenth of that of the substrate. Even after oxidation for 100 h, the Al2O3 phase was the primary phase in the surface coating (850 °C), with the thickness of the oxide film increasing to 0.65 μm at 950 °C. When the temperature was increased beyond 1050 °C, the elemental Al and Ni were consumed in the formation of the oxide scale, which underwent spallation at several locations. The oxidation products of Cr, which were produced in large amounts and had a prism-like structure, controlled the subsequent oxidation behavior at the surface.

Development of Ion-Plasma Coatings for Protecting Intermetallic Refractory Alloys VKNA-1V and VKNA-25 in the Temperature Range of 1200 - 1250°C

Science.gov (United States)

Budinovskii, S. A.; Matveev, P. V.; Smirnov, A. A.

2017-05-01

Multilayer heat-resistant ion-plasma coatings for protecting the parts of the hot duct of gas-turbine engines produced from refractory nickel alloys based on VKNA intermetallics from high-temperature oxidation are considered. Coatings of the Ni - Cr - Al (Ta, Re, Hf, Y) + Al - Ni - Y systems are tested for high-temperature strength at 1200 and 1250°C. Metallographic and microscopic x-ray spectrum analyses of the structure and composition of the coatings in the initial condition and after the testing are performed. The effect of protective coatings of the Ni - Cr - Al - Hf + Al - Ni - Y systems on the long-term strength of alloys VKNA-1V and VKNA-25 at 1200°C is studied.

Establishing release limits for 3H, 14C, 85Kr, and 129I

International Nuclear Information System (INIS)

Kocher, D.C.; Killough, G.G.

1983-01-01

Tritium ( 3 H), 14 C, 85 Kr, and 129 I are the most important globally dispersed radionuclides released from the nuclear fuel cycle. In this paper, we investigate whether global transport of these radionuclides could also be important in assessing doses to individuals in critical groups of the population

The influence of heat treatment and plastic deformation on the bio-degradation of a Mg-Y-RE alloy.

Science.gov (United States)

Gunde, Petra; Furrer, Angela; Hänzi, Anja C; Schmutz, Patrik; Uggowitzer, Peter J

2010-02-01

In this study the bio-degradation behavior of a Mg-Y-RE alloy in different heat treatment states with respect to the alloy's potential application as biodegradable implant material was investigated by electrochemical impedance spectroscopy in two body-similar fluids. The heat treatments increase the degradation resistance of the alloy and lead to the formation of a thermal oxide layer on the sample surface and to a change in microstructure such as the distribution of yttrium. The varying Y distribution in the alloy does not significantly influence the degradation behavior, and all samples show a similar low polarization resistance. However, samples with a thermal oxide layer, which consists mainly of Y(2)O(3), degrade much more slowly and feature remarkably high polarization resistance. Nevertheless, in some cases localized corrosion attack occurs and drastically impairs performance. Cracks in the oxide layer, intentionally induced by straining of the samples and which in practice could originate from the implantation process, reduce the corrosion resistance. However, these samples perform still better than polished specimens and show a macroscopically homogeneous degradation behavior without localized corrosion. Microscopically, corrosion attacks start at the cracks and undermining of the oxide layer occurs with time. For all the material conditions a remarkable dependence of the degradation rate on the electrolyte is noted. (c) 2009 Wiley Periodicals, Inc.

Synthesis Of NiCrAlC alloys by mechanical alloying; Sintese de ligas NiCrAlC por moagem de alta energia

Energy Technology Data Exchange (ETDEWEB)

Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M., E-mail: alissonkws@gmail.co [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil)

2010-07-01

The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni{sub 3}Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

Lattice vibrations study of Ga1-xInxAsySb1-y quaternary alloys with low (In, As) content grown by liquid phase epitaxy

International Nuclear Information System (INIS)

Olvera-Herandez, J; Olvera-Cervantes, J; Rojas-Lopez, M; Navarro-Contreras, H; Vidal, M A; Anda, F de

2006-01-01

Raman scattering spectroscopy was used to measure and analyze the lattice vibrations in some quaternary Ga 1-x In x As y Sb 1-y alloys with low (In, As) contents (0.03 0 C. High Resolution X-Ray Diffraction results showed profiles associated with a quaternary layer lattice matched to the GaSb substrate as obtained from the (004) reflection. The experimental diffractograms were simulated to estimate alloy composition, thickness and lattice mismatch of the layer. Raman scattering results show phonon frequencies associated to the TO and LO GaAs-like modes as well as GaSb + InAs-like mode, which are characteristic of this quaternary alloy. The As content dependence of the phonon frequency measured in this alloy for low (In, As) contents agree well with the modified Random-Element Isodisplacement (REI) model and also with other available experimental reports. This method can also be used to estimate alloy compositions for this kind of quaternary alloys

Preparation and characterization of Pd{sub x}Ag{sub y}/C electrocatalysts for ethanol electrooxidation reaction in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Li Guanglan [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Jiang Luhua [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Jiang Qian [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Wang Suli [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Sun Gongquan, E-mail: gqsun@dicp.ac.cn [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2011-09-01

Highlights: {center_dot} The effects of Pd or PdAg particle size and PdAg alloy degrees on the EOR activity are investigated. {center_dot} The Pd lattice constant of the PdAg increases with increasing the Ag content. {center_dot} The EOR activity of the PdAg/C presents a 'volcano' plot with increasing the Pd lattice constant. {center_dot} The optimal Pd/Ag atomic ratio locates between 2/1 and 3/1. {center_dot} The EOR activity of the PdAg/C increases with increasing the PdAg particle size from 3.4 to 5.2 nm. - Abstract: Carbon-supported bimetallic PdAg catalysts with Pd/Ag atomic ratios varying from 4/1 to 1/2 were prepared by an impregnation-reduction method. The impregnated black mixture was treated in H{sub 2}/N{sub 2} atmosphere at a temperature varying from 180 to 500 deg. C. The obtained Pd{sub x}Ag{sub y}/C catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA). XRD results show that the lattice constant of Pd is dilated, suggesting the formation of PdAg alloy. The lattice constant of Pd for the Pd{sub x}Ag{sub y}/C-500 (reduced at 500 deg. C by H{sub 2}) increases linearly and the average metal particle size decreases slightly from 6.8 to 5.1 nm with increasing Ag fractions from 20% to 67% in the PdAg composition. For Pd{sub x}Ag{sub y}/C catalysts with a certain specific Pd/Ag atomic ratio, e.g., Pd{sub 2}Ag{sub 1}/C, the dilated lattice constant of Pd is independent of the reducing temperature, indicating the alloy degree for the Pd{sub 2}Ag{sub 1}/C-t catalysts is comparable. The average metal particle size for the Pd{sub 2}Ag{sub 1}/C-t catalysts increases from 3.4 to 5.2 nm with H{sub 2} reduction temperature increasing from 180 to 500 deg. C. The potentiodynamic measurements on ethanol electrooxidation reaction (EOR) show that the catalytic activities for the Pd{sub x}Ag{sub y}/C-t catalysts toward the EOR are improved by alloying Pd with Ag. At

Age hardening in mechanically alloyed Al-Mg-Li-C-O

Energy Technology Data Exchange (ETDEWEB)

Papazian, J.M. (Corporate Research Center, Grumman Corporation, Bethpage, NY (USA)); Gilman, P. (Allied-Signal Inc., Morristown, NJ (USA))

1990-05-01

The age-hardening behavior of a series of mechanically alloyed Al-Mg-Li-C-O alloys containing 3.0-4.0 wt.% Mg and 1.3-1.75 wt.% Li was studied using hardness tests, differential scanning calorimetry (DSC) and transmission electron microscopy. The hardness tests showed an increased hardness after 100degC aging in all the alloys containing at least 1.5 at.% Li. Likewise, the calorimetry results showed the presence of pronounced precipitate dissolution peaks in these same alloys after 100degC aging. The volume fraction of precipitates formed (as measured by the dissolution enthalpies of the DSC peaks) increased systematically with increasing solute content. Transmission electron microscopy after 100 and 190degC aging showed images and diffraction spots similar to those of {delta}' (Al{sub 3}Li). Comparison of the DSC results with results from binary Al-Li and Al-Mg alloys indicated that the precipitates formed in the Al-Mg-Li-C-O alloys were similar to those formed in binary Al-Li alloys, and that the primary role of the magnesium was to lower the solid solubility of lithium. (orig.).

Formation of long-period stacking ordered structures in Mg88M5Y7 (M = Ti, Ni and Pb) casting alloys

International Nuclear Information System (INIS)

Jin, Qian-Qian; Fang, Can-Feng; Mi, Shao-Bo

2013-01-01

Highlights: •Apart from 18R-LPSO, 14H-LPSO structure was determined in the Mg-Ni-Y alloys. •The appearance of twin-related structure in 18R-LPSO structure results from the stacking faults in the stacking sequence of the closely packed planes. •A new (Pb, Mg) 2 Y phase with a body-centered orthorhombic structure was determined in the Mg-Pb-Y alloy. •No LPSO structures were found in the Mg-Pb-Y and Mg-Ti-Y casting alloys. -- Abstract: Formation of long-period stacking ordered (LPSO) structures is investigated in Mg 88 M 5 Y 7 (M = Ti, Ni and Pb) casting alloys by means of electron microscopy and X-ray diffraction. In the Mg 88 Ni 5 Y 7 casting alloy, 14H-LPSO structure is observed in a small amount, which coexists with 18R-LPSO structure. The appearance of stacking faults in 18R-LPSO structure results in twin-related structure in the stacking sequence of the closely packed planes. A new (Pb, Mg) 2 Y phase with a body-centered orthorhombic structure is determined in the Mg 88 Pb 5 Y 7 alloy. No LPSO structures are found in the Mg 88 Pb 5 Y 7 and Mg 88 Ti 5 Y 7 casting alloys. In terms of the atomic radius and heat of mixing, the formation ability of LPSO structure in the present alloys is discussed

Medical Isotope Program: O-18, C-13, and Xe-129 Final Report CRADA No. TC-2043-02

Energy Technology Data Exchange (ETDEWEB)

Scheibner, K. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fought, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-09-27

This was a collaborative effort between the University of California, Lawrence Livermore National Laboratory (LLNL) and Spectra Gases, Inc., to develop new and cheaper sources of Oxgyen-18 (O-18), Carbon-13 (C-13), and Xenon-129 (Xe-129), and to develop new applications of these stable medical isotopes in medicine resulting in a substantial increase in stable isotopes that are important to human health sciences.

3H, 14C, 85Kr and 129I production in nuclear facilities

International Nuclear Information System (INIS)

Castellani, F.; Ocone, R.

1984-01-01

The production of 3 H, 14 C, 85 Kr and 129 I in nuclear power plants is evaluated. In particular the plant components where these radioisotopes can be formed and the formation processes, with corresponding cross sections, are considered. Furthermare their release in the plants and the fraction transfered to the reprocessing are examined

Passivity of alloy C-22 in NaCl solutions

International Nuclear Information System (INIS)

Rodriguez, Martin A.; Carranza, Ricardo M.

2004-01-01

Alloy C-22 has been proposed as the corrosion resistant barrier of high-level waste nuclear containers. This alloy must be resistant to corrosion in multi-ionic solutions for a period of time as long as 10,000 years. The aim of the present work was to study the corrosion behavior of alloy C-22 in NaCl solutions. General and crevice corrosion were studied by means of electrochemical techniques. Open circuit potential was measured over the time, electrochemical impedance spectroscopy (EIS) measurements were carried out at open circuit and passivity potentials, as well as cyclic potentiodynamic polarization curves. Corrosion rates obtained by EIS measurements were acceptable for a waste nuclear container ( P ) values increased with open circuit potential and polarization time at constant potential. This was attributed to an increase in oxide film thickness and its aging respectively. The passive oxide form on alloy C-22 at the studied conditions presented a n-type semiconductor behavior in the passive potential range. Repassivation potential values (E R1 ) were determined for alloy C-22 at the studied conditions using PCA probes. (author) [es

Glass-formation and hardness of Cu-Y alloys

International Nuclear Information System (INIS)

Satta, Marta; Rizzi, Paola; Baricco, Marcello

2009-01-01

Metallic glasses exhibit particularly attractive mechanical properties, like high stresses to fracture and large elastic strain (up to 2%), but they show generally low plasticity. Aim of this work is to investigate the glass forming range in the Cu-Y system, in order to form the ductile CuY phase (CsCl structure) upon crystallization. Cu 58 Y 42 , Cu 50 Y 50 and Cu 33 Y 67 alloys have been prepared by rapid solidification and copper mould casting, obtaining ribbons and cylindrical shaped ingots, with diameter of 2 mm. Fully amorphous, partially amorphous and fully crystalline samples have been obtained for different compositions and quenching conditions. In some cases, the X-ray diffraction results, analysed using the Rietveld method, showed CuY nanocrystals embedded in an amorphous matrix. The microstructure was studied by transmission electron microscopy (TEM) and the presence of nanocrystals of the ductile phase CuY has been confirmed. Microhardness results showed a softening of the amorphous phase due to the presence of CuY nanocrystals and a hardening due to the Cu 2 Y phase.

Microstructure and properties of hot extruded Mg-3Zn-Y-xCu (x = 0, 1, 3, 5) alloys

Energy Technology Data Exchange (ETDEWEB)

Liu, Bao-sheng; Kuang, Ya-fei; Fang, Da-qing; Chai, Yue-sheng [Taiyuan Univ. of Science and Technology (China). College of Materials Science and Engineering; Taiyuan Univ. of Science and Technology (China). Engineering Research Center for Magnesium Alloys of Shanxi Province; Zhang, Yue-zhong [Taiyuan Univ. of Science and Technology (China). Engineering Research Center for Magnesium Alloys of Shanxi Province; Taiyuan Univ. of Science and Technology (China). College of Chemical and Biological Engineering

2017-04-15

In petroleum drilling engineering, materials with high strength and rapid degradation are required for degradable fracturing ball applications. In this work, the microstructure, mechanical properties, and corrosion behavior of extruded Mg-3Zn-Y-xCu (x = 0, 1, 3, 5 weight percent) alloys are investigated using optical microscopy, scanning electronic microscopy equipped with energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electronic microscopy, compression tests, electrochemical measurements, and hydrogen evolution tests, to explore their potential as excellent candidate alloys for degradable fracturing ball applications. It is found that the Mg-3Zn-Y alloy is mainly composed of α-Mg, Mg{sub 3}Zn{sub 3}Y{sub 2}, and Mg{sub 3}Zn{sub 6}Y phases. After Cu addition, a new MgZnCu phase is formed, while the Mg{sub 3}Zn{sub 3}Y{sub 2} phase disappears. The Mg-3Zn-Y-3Cu alloy shows the highest compressive strength (473 MPa) and yield strength (402 MPa), mainly attributed to the combined effect of the fine-grain and dispersed precipitation of Mg{sub 3}Zn{sub 6}Y and MgZnCu. The corrosion rate of Mg-3Zn-Y-3Cu reaches 0.41 mm day{sup -1} in 3.5 wt.% KCl solution. Consequently, Mg-3Zn-Y-3Cu alloy is a suitable degradable fracturing ball-seat material.

Mechanical properties of Al-Cu alloy-SiC composites

Science.gov (United States)

Anggara, B. S.; Handoko, E.; Soegijono, B.

2014-09-01

The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

Mechanical properties of Al-Cu alloy-SiC composites

Energy Technology Data Exchange (ETDEWEB)

Anggara, B. S., E-mail: anggorobs1960@yahoo.com [Jurusan Fisika, FMIPA Universitas Negeri Jakarta, Indonesia 13220 and PPS Ilmu Material, Department Fisika, FMIPA, Universitas Indonesia (Indonesia); Handoko, E. [Jurusan Fisika, FMIPA Universitas Negeri Jakarta, 13220 (Indonesia); Soegijono, B. [PPS Ilmu Material, Department Fisika, FMIPA, Universitas Indonesia (Indonesia)

2014-09-25

The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

In vitro and in vivo corrosion, cytocompatibility and mechanical properties of biodegradable Mg-Y-Ca-Zr alloys as implant materials.

Science.gov (United States)

Chou, Da-Tren; Hong, Daeho; Saha, Partha; Ferrero, Jordan; Lee, Boeun; Tan, Zongqing; Dong, Zhongyun; Kumta, Prashant N

2013-11-01

This study introduces a class of biodegradable Mg-Y-Ca-Zr alloys novel to biological applications and presents evaluations for orthopedic and craniofacial implant applications. Mg-Y-Ca-Zr alloys were processed using conventional melting and casting techniques. The effects of increasing Y content from 1 to 4 wt.% as well as the effects of T4 solution treatment were assessed. Basic material phase characterization was conducted using X-ray diffraction, optical microscopy and scanning electron microscopy. Compressive and tensile tests allowed for the comparison of mechanical properties of the as-cast and T4-treated Mg-Y-Ca-Zr alloys to pure Mg and as-drawn AZ31. Potentiodynamic polarization tests and mass loss immersion tests were used to evaluate the corrosion behavior of the alloys. In vitro cytocompatibility tests on MC3T3-E1 pre-osteoblast cells were also conducted. Finally, alloy pellets were implanted into murine subcutaneous tissue to observe in vivo corrosion as well as local host response through H&E staining. SEM/EDS analysis showed that secondary phase intermetallics rich in yttrium were observed along the grain boundaries, with the T4 solution treatment diffusing the secondary phases into the matrix while increasing the grain size. The alloys demonstrated marked improvement in mechanical properties over pure Mg. Increasing the Y content contributed to improved corrosion resistance, while solution-treated alloys resulted in lower strength and compressive strain compared to as-cast alloys. The Mg-Y-Ca-Zr alloys demonstrated excellent in vitro cytocompatibility and normal in vivo host response. The mechanical, corrosion and biological evaluations performed in this study demonstrated that Mg-Y-Ca-Zr alloys, especially with the 4 wt.% Y content, would perform well as orthopedic and craniofacial implant biomaterials. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Study crevice corrosion alloys C-22 and 625 by electrochemical noise

International Nuclear Information System (INIS)

Ungaro, María L.; Carranza, Ricardo M.; Rodríguez, Martín A.

2013-01-01

C-22 and 625 alloys are two of the Ni –Cr-Mo alloys considered as candidate materials to form the corrosion resistance engineered barriers for nuclear waste repositories. The corrosion resistance of these alloys is remarkable in a wide variety of environments. Despite of their resistance these alloys are susceptible to crevice corrosion in a certain aggressive environments. This work presents the use of electrochemical noise technique to study crevice corrosion susceptibility of alloys C-22 and 625 in 1M NaCl acidic solutions at 60ºC and 90ºC. Asymmetrical electrodes and a complementary platinum electrode were used to assess the influence of cathodic reaction in crevice process. The obtained records were analyzed directly and through statistical parameters. The potential drop and the simultaneous increment of the current records indicated the occurrence of crevice corrosion. The alternative use of a platinum electrode resulted in higher currents and higher potentials and reduced the induction time to crevice formation. The reason for this behavior is that platinum surface allows faster cathodic reactions than C-22 and 625 alloys. The standard deviation of the current records was responsive to the crevice corrosion intensity. C-22 alloy had better crevice corrosion performance than 625 alloy. (author)

Ductility improvement by twinning and twin–slip interaction in a Mg-Y alloy

International Nuclear Information System (INIS)

Zhou, Na; Zhang, Zhenyan; Jin, Li; Dong, Jie; Chen, Bin; Ding, Wenjiang

2014-01-01

Highlights: • A high elongation of ∼33% was achieved for magnesium alloy through common extrusion. • Basal slip and extension twinning are the dominant deformation modes for the high ductility. • Non-basal slip, contraction twinning and twin-slip interaction also contribute to the ductility. - Abstract: An extruded Mg-3.0Y alloy with non-basal texture of 〈42 ¯ 2 ¯ 3〉 component was fabricated by common extrusion and exhibited a high elongation of ∼33%. The deformation modes and microstructure evolution of the extruded Mg-3.0Y alloy during the tensile test at room temperature were investigated to explore the reasons for the high ductility by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The results suggested that texture changed from 〈42 ¯ 2 ¯ 3〉 to 〈101 ¯ 0〉 component during the tensile deformation, which is attributed the slip and twinning activity. Basal slip and extension twinning are the dominant deformation modes for the high ductility. Meanwhile, the activation of non-basal slip, contraction twinning and twin–slip interaction also contributes to the good ductility of Mg-3.0Y alloy

Review of global environmental-transport models for 3H, 14C, 85Kr, and 129I

International Nuclear Information System (INIS)

Kocher, D.C.; Killough, G.G.

1983-01-01

Global environmental transport models for the long-lived and mobile radionuclides 3 H, 14 C, 85 Kr, and 129 I are reviewed from the perspective of their application to collective dose assessments following releases, e.g., from the nuclear fuel cycle. Contributions to the collective dose commitment from first-pass local and regional exposures are compared. Current global models for 14 C and 85 Kr appear to be satisfactory for dose assessment purposes. Global modeling for 3 H is more difficult than for 14 C and 85 Kr, because of the different physico-chemical forms in which atmospheric releases occur. Global models for 129 I models indicate the primary importance of retention in surface soils for collective doses during the first 10 4 years following atmospheric releases and the importance of long-term transport to ocean sediments for reducing the dose commitment

Electrical Properties of a Thin Anodized Capacitor Made of Y-Doped Al Alloy Film

Science.gov (United States)

Onozuka, Tomotake; Sasaki, Hayato; Mikuni, Naohiro; Shinkai, Satoko; Sasaki, Katsutaka; Yamane, Misao; Abe, Yoshio

2005-09-01

We have prepared an Al-Y anodized capacitor using sputter-deposited Al-Y alloy film with 5 at. % Y atoms, and evaluated the capacitor properties and the leakage current properties before and after heat treatment. In addition, the characterization of Al-Y anodized films was examined by X-ray diffraction, Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy analyses. As a result, it is revealed that the thermal stability of an Al-Y anodized capacitor is superior to that of a pure Al anodized capacitor because of its excellent passive nature, and the loss properties can be improved by increasing the heat treatment temperature in air because of the reduction of the equivalent series resistance. Furthermore, it is clarified that the cause of the short-circuited state observed at 550°C is the formation of a narrow capillary-like conduction path of metallic Al atoms as a result of the interdiffusion of Al.

Tungsten wire-nickel base alloy composite development

Science.gov (United States)

Brentnall, W. D.; Moracz, D. J.

1976-01-01

Further development and evaluation of refractory wire reinforced nickel-base alloy composites is described. Emphasis was placed on evaluating thermal fatigue resistance as a function of matrix alloy composition, fabrication variables and reinforcement level and distribution. Tests for up to 1,000 cycles were performed and the best system identified in this current work was 50v/o W/NiCrAlY. Improved resistance to thermal fatigue damage would be anticipated for specimens fabricated via optimized processing schedules. Other properties investigated included 1,093 C (2,000 F) stress rupture strength, impact resistance and static air oxidation. A composite consisting of 30v/o W-Hf-C alloy fibers in a NiCrAlY alloy matrix was shown to have a 100-hour stress rupture strength at 1,093 C (2,000 F) of 365 MN/square meters (53 ksi) or a specific strength advantage of about 3:1 over typical D.S. eutectics.

78 FR 30269 - Foreign-Trade Zone 129-Bellingham, Washington; Authorization of Production Activity; T.C. Trading...

Science.gov (United States)

2013-05-22

... proposed production activity to the Foreign-Trade Zones (FTZ) Board on behalf of T.C. Trading Company, Inc... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-8-2013] Foreign-Trade Zone 129--Bellingham, Washington; Authorization of Production Activity; T.C. Trading Company, Inc. (Eyeglass Assembly and Kitting...

Microstructure and corrosion properties of as sub-rapid solidification Mg-Zn-Y-Nd alloy in dynamic simulated body fluid for vascular stent application.

Science.gov (United States)

Wang, Jun; Wang, Liguo; Guan, Shaokang; Zhu, Shijie; Ren, Chenxing; Hou, Shusen

2010-07-01

Magnesium alloy stent has been employed in animal and clinical experiment in recent years. It has been verified to be biocompatible and degradable due to corrosion after being implanted into blood vessel. Mg-Y-Gd-Nd alloy is usually used to construct an absorbable magnesium alloy stent. However, the corrosion resistant of as cast Mg-Y-Gd-Nd alloy is poor relatively and the control of corrosion rate is difficult. Aiming at the requirement of endovascular stent in clinic, a new biomedical Mg-Zn-Y-Nd alloy with low Zn and Y content (Zn/Y atom ratio 6) was designed, which exists quasicrystals to improve its corrosion resistance. Additionally, sub-rapid solidification processing was applied for preparation of corrosion-resisting Mg-Zn-Y-Nd and Mg-Y-Gd-Nd alloys. Compared with the as cast sample, the corrosion behavior of alloys in dynamic simulated body fluid (SBF) (the speed of body fluid: 16 ml/800 ml min(-1)) was investigated. The results show that as sub-rapid solidification Mg-Zn-Y-Nd alloy has the better corrosion resistance in dynamic SBF due to grain refinement and fine dispersion distribution of the quasicrystals and intermetallic compounds in alpha-Mg matrix. In the as cast sample, both Mg-Zn-Y-Nd and Mg-Y-Gd-Nd alloys exhibit poor corrosion resistance. Mg-Zn-Y-Nd alloy by sub-rapid solidification processing provides excellent corrosion resistance in dynamic SBF, which open a new window for biomedical materials design, especially for vascular stent application.

78 FR 7395 - Foreign-Trade Zone 129-Bellingham, WA; Notification of Proposed Production Activity; T.C. Trading...

Science.gov (United States)

2013-02-01

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-8-2013] Foreign-Trade Zone 129--Bellingham, WA; Notification of Proposed Production Activity; T.C. Trading Company, Inc. (Eyeglass Assembly and Kitting... activity on behalf of T.C. Trading Company, Inc. (T.C. Trading), located in Blaine, Washington. The...

Compositional dependence of the band-gap of Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys

Energy Technology Data Exchange (ETDEWEB)

Wendav, Torsten, E-mail: wendav@physik.hu-berlin.de [AG Theoretische Optik & Photonik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Fischer, Inga A.; Oehme, Michael; Schulze, Jörg [Institut für Halbleitertechnik, Universität Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart (Germany); Montanari, Michele; Zoellner, Marvin Hartwig; Klesse, Wolfgang [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Capellini, Giovanni [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, 00146 Roma (Italy); Driesch, Nils von den; Buca, Dan [Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies, Forschungszentrum Jülich, 52428 Jülich (Germany); Busch, Kurt [AG Theoretische Optik & Photonik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Max-Born-Institut, Max-Born-Str. 2 A, 12489 Berlin (Germany)

2016-06-13

The group-IV semiconductor alloy Ge{sub 1−x−y}Si{sub x}Sn{sub y} has recently attracted great interest due to its prospective potential for use in optoelectronics, electronics, and photovoltaics. Here, we investigate molecular beam epitaxy grown Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys lattice-matched to Ge with large Si and Sn concentrations of up to 42% and 10%, respectively. The samples were characterized in detail by Rutherford backscattering/channeling spectroscopy for composition and crystal quality, x-ray diffraction for strain determination, and photoluminescence spectroscopy for the assessment of band-gap energies. Moreover, the experimentally extracted material parameters were used to determine the SiSn bowing and to make predictions about the optical transition energy.

Cavitation erosion behavior of Hastelloy C-276 nickel-based alloy

Energy Technology Data Exchange (ETDEWEB)

Li, Zhen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Han, Jiesheng; Lu, Jinjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Chen, Jianmin, E-mail: chenjm@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2015-01-15

Highlights: • Cavitation erosion behavior of Hastelloy C-276 was studied by ultrasonic apparatus. • The cavitation-induced precipitates formed in the eroded surface for Hastelloy C-276. • The selective cavitation erosion was found in Hastelloy C-276 alloy. - Abstract: The cavitation erosion behavior of Hastelloy C-276 alloy was investigated using an ultrasonic vibratory apparatus and compared with that of 316L stainless steel. The mean depth of erosion (MDE) and erosion rate (ER) curves vs. test time were attained for Hastelloy C-276 alloy. Morphology and microstructure evolution of the eroded surface were observed by scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and the predominant erosion mechanism was also discussed. The results show that the MDE is about 1/6 times lower than that of the stainless steel after 9 h of testing. The incubation period of Hastelloy C-276 alloy is about 3 times longer than that of 316L stainless steel. The cavitation-induced nanometer-scaled precipitates were found in the local zones of the eroded surface for Hastelloy C-276. The selective cavitation erosion was found in Hastelloy C-276 alloy. The formation of nanometer-scaled precipitates in the eroded surface may play a significant role in the cavitation erosion resistance of Hastelloy C-276.

Cavitation erosion behavior of Hastelloy C-276 nickel-based alloy

International Nuclear Information System (INIS)

Li, Zhen; Han, Jiesheng; Lu, Jinjun; Chen, Jianmin

2015-01-01

Highlights: • Cavitation erosion behavior of Hastelloy C-276 was studied by ultrasonic apparatus. • The cavitation-induced precipitates formed in the eroded surface for Hastelloy C-276. • The selective cavitation erosion was found in Hastelloy C-276 alloy. - Abstract: The cavitation erosion behavior of Hastelloy C-276 alloy was investigated using an ultrasonic vibratory apparatus and compared with that of 316L stainless steel. The mean depth of erosion (MDE) and erosion rate (ER) curves vs. test time were attained for Hastelloy C-276 alloy. Morphology and microstructure evolution of the eroded surface were observed by scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and the predominant erosion mechanism was also discussed. The results show that the MDE is about 1/6 times lower than that of the stainless steel after 9 h of testing. The incubation period of Hastelloy C-276 alloy is about 3 times longer than that of 316L stainless steel. The cavitation-induced nanometer-scaled precipitates were found in the local zones of the eroded surface for Hastelloy C-276. The selective cavitation erosion was found in Hastelloy C-276 alloy. The formation of nanometer-scaled precipitates in the eroded surface may play a significant role in the cavitation erosion resistance of Hastelloy C-276

Phase Transformation Behavior of Oxide Particles Formed in Mechanically Alloyed Fe-5Y{sub 2}O{sub 3} Powder

Energy Technology Data Exchange (ETDEWEB)

Kim, Ga Eon; Choi, Jung-Sun; Noh, Sanghoon; Kang, Suk Hoon; Choi, Byoung Kwon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Deajeon (Korea, Republic of); Kim, Young Do [Hanyang University, Seoul (Korea, Republic of)

2017-05-15

The phase transformation behavior of the oxides formed in mechanically alloyed Fe-5Y{sub 2}O{sub 3} powder is investigated. Non-stoichiometric Y-rich and Fe-rich oxides with sizes of less than 300 nm are observed in the mechanically alloyed powder. The diffusion and redistribution reactions of the elements in these oxides during heating of the powder above 800 ℃ were observed, and these reactions result in the formation of a Y{sub 3}Fe{sub 5}O{sub 12} phase after heating at 1050 ℃. Thus, it is considered that the Y{sub 2}O{sub 3} powder and some Fe powder are formed from the non-stoichiometric Y-rich and Fe-rich oxides after the mechanical alloying process, and a considerable energy accumulated during the mechanical alloying process leads to a phase transformation of the Y-rich and Fe-rich oxides to Y{sub α}Fe{sub β}O{sub γ}-type phase during heating.

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

Laser surface alloying of aluminium-transition metal alloys

Directory of Open Access Journals (Sweden)

Almeida, A.

1998-04-01

Full Text Available Laser surface alloying has been used as a tool to produce hard and corrosion resistant Al-transition metal (TM alloys. Cr and Mo are particularly interesting alloying elements to produce stable highstrength alloys because they present low diffusion coefficients and solid solubility in Al. To produce Al-TM surface alloys a two-step laser process was developed: firstly, the material is alloyed using low scanning speed and secondly, the microstructure is modified by a refinement step. This process was used in the production of Al-Cr, Al-Mo and Al-Nb surface alloys by alloying Cr, Mo or Nb powder into an Al and 7175 Al alloy substrate using a CO₂ laser. This paper presents a review of the work that has been developed at Instituto Superior Tecnico on laser alloying of Al-TM alloys, over the last years.

En el presente trabajo se estudia la aleación superficial mediante láser de aluminio con metales de transición. El cromo y el molibdeno son particularmente interesantes porque producen aleaciones de alta resistencia y por el bajo coeficiente de difusión y solución sólida en aluminio. Para producir estas aleaciones se ha seguido un procedimiento desarrollado en dos partes. En primer lugar, el material se alea usando una baja velocidad de procesado y en segundo lugar la estructura se modifica mediante un refinamiento posterior. Este procedimiento se ha empleado en la producción de aleaciones Al-Cr, Al-Mo y Al-Nb mediante aleación con láser de CO₂ de polvos de Cr, Mo o Nb en aluminio y la aleación 7175. Este trabajo es una revisión del desarrollado en el Instituto Superior Técnico de Lisboa en los últimos años.

Internal Friction of Austenitic Fe-Mn-C-Al Alloys

Science.gov (United States)

Lee, Young-Kook; Jeong, Sohee; Kang, Jee-Hyun; Lee, Sang-Min

2017-12-01

The internal friction (IF) spectra of Fe-Mn-C-Al alloys with a face-centered-cubic (fcc) austenitic phase were measured at a wide range of temperature and frequency ( f) to understand the mechanisms of anelastic relaxations occurring particularly in Fe-Mn-C twinning-induced plasticity steels. Four IF peaks were observed at 346 K (73 °C) (P1), 389 K (116 °C) (P2), 511 K (238 °C) (P3), and 634 K (361 °C) (P4) when f was 0.1 Hz. However, when f increased to 100 Hz, whereas P1, P2, and P4 disappeared, only P3 remained without the change in peak height, but with the increased peak temperature. P3 matches well with the IF peak of Fe-high Mn-C alloys reported in the literature. The effects of chemical composition and vacancy (v) on the four IF peaks were also investigated using various alloys with different concentrations of C, Mn, Al, and vacancy. As a result, the defect pair responsible for each IF peak was found as follows: a v-v pair for P1, a C-v pair for P2, a C-C pair for P3, and a C-C-v complex (major effect) + a Mn-C pair (minor effect) for P4. These results showed that the IF peaks of Fe-Mn-C-Al alloys reported previously were caused by the reorientation of C in C-C pairs, not by the reorientation of C in Mn-C pairs.

Glass-formation and hardness of Cu-Y alloys

Energy Technology Data Exchange (ETDEWEB)

Satta, Marta; Rizzi, Paola [Dipartimento di Chimica IFM and NIS/INSTM/CNISM, Universita di Torino, v. Giuria 9, I-10125 Torino (Italy); Baricco, Marcello, E-mail: marcello.baricco@unito.i [Dipartimento di Chimica IFM and NIS/INSTM/CNISM, Universita di Torino, v. Giuria 9, I-10125 Torino (Italy)

2009-08-26

Metallic glasses exhibit particularly attractive mechanical properties, like high stresses to fracture and large elastic strain (up to 2%), but they show generally low plasticity. Aim of this work is to investigate the glass forming range in the Cu-Y system, in order to form the ductile CuY phase (CsCl structure) upon crystallization. Cu{sub 58}Y{sub 42}, Cu{sub 50}Y{sub 50} and Cu{sub 33}Y{sub 67} alloys have been prepared by rapid solidification and copper mould casting, obtaining ribbons and cylindrical shaped ingots, with diameter of 2 mm. Fully amorphous, partially amorphous and fully crystalline samples have been obtained for different compositions and quenching conditions. In some cases, the X-ray diffraction results, analysed using the Rietveld method, showed CuY nanocrystals embedded in an amorphous matrix. The microstructure was studied by transmission electron microscopy (TEM) and the presence of nanocrystals of the ductile phase CuY has been confirmed. Microhardness results showed a softening of the amorphous phase due to the presence of CuY nanocrystals and a hardening due to the Cu{sub 2}Y phase.

New view on In{sub x}Ga{sub 1-x}N{sub y}As{sub 1-y}alloys

Energy Technology Data Exchange (ETDEWEB)

Elyukhin, Vyacheslav A. [Departamento de Ingenieria Electrica, Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Avenida Instituto Politecnico Nacional 2508, 07360, Mexico (Mexico)

2015-12-15

Semiconductors with isoelectronic centers are actively studied to fabricate arrays of identical single photon emitters. Self-assembling of 4N10In and 1N4In clusters in GaAs-rich In{sub x}Ga{sub 1-x}N{sub y}As{sub 1-y} is represented. All or almost all In atoms are in 4N10In clusters from 0 to 800 C in In{sub x}Ga{sub 1-x}N{sub y}As{sub 1-y} with x = 1 x 10{sup -4}, y = 1 x 10{sup -4} and x = 1 x 10{sup -5}, y = 1 x 10{sup -5}. All or almost all nitrogen atoms are in 1N4In clusters if x = 0.01, y = 1 x 10{sup -4} and x = 1 x 10{sup -3}, y = 1 x 10{sup -6}. There are both types of clusters in alloys with x = 5 x 10{sup -5}, y = 5 x 10{sup -7}; x = 2 x 10{sup -4}, y = 2 x 10{sup -6}; x = 1 x 10{sup -4}, y = 1 x 10{sup -5} and x = 2 x 10{sup -3}, y = 2 x 10{sup -4} and portions of nitrogen atoms in clusters depend on the composition and temperature. Thus, In{sub x}Ga{sub 1-x}N{sub y}As{sub 1-y} are promising semiconductors to obtain arrays of identical isoelectronic clusters with the desirable density. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Development of low-Cr ODS FeCrAl alloys for accident-tolerant fuel cladding

Science.gov (United States)

Dryepondt, Sebastien; Unocic, Kinga A.; Hoelzer, David T.; Massey, Caleb P.; Pint, Bruce A.

2018-04-01

Low-Cr oxide dispersion strengthened (ODS) FeCrAl alloys were developed as accident tolerant fuel cladding because of their excellent oxidation resistance at very high temperature, high strength and improved radiation tolerance. Fe-12Cr-5Al wt.% gas atomized powder was ball milled with Y2O3+FeO, Y2O3+ZrO2 or Y2O3+TiO2, and the resulting powders were extruded at 950 °C. The resulting fine grain structure, particularly for the Ti and Zr containing alloys, led to very high strength but limited ductility. Comparison with variants of commercial PM2000 (Fe-20Cr-5Al) highlighted the significant impact of the powder consolidation step on the alloy grain size and, therefore, on the alloy mechanical properties at T < 500 °C. These low-Cr compositions exhibited good oxidation resistance at 1400 °C in air and steam for 4 h but could not form a protective alumina scale at 1450 °C, similar to observations for fine grained PM2000 alloys. The effect of alloy grain size, Zr and Ti additions, and impurities on the alloy mechanical and oxidation behaviors are discussed.

Variations of color with alloying elements in Pd-free Au-Pt-based high noble dental alloys

International Nuclear Information System (INIS)

Shiraishi, Takanobu; Takuma, Yasuko; Miura, Eri; Fujita, Takeshi; Hisatsune, Kunihiro

2007-01-01

The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au-Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au-Pt-X (X = In, Sn, Fe, Zn) and quaternary Au-Pt-In-Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au-10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C *. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au-Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L *, and the addition of Sn gave a very light tint of red to the parent alloy. Although red-green chromaticity index a * contributed to chroma to some extent, contribution of yellow-blue chromaticity index b * was much greater in determining chroma in this Pd-free Au-Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au-Pt-based high noble dental alloys

Variations of color with alloying elements in Pd-free Au-Pt-based high noble dental alloys

Energy Technology Data Exchange (ETDEWEB)

Shiraishi, Takanobu [Department of Dental and Biomedical Materials Science, Unit of Basic Medical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588 (Japan)]. E-mail: siraisi@nagasaki-u.ac.jp; Takuma, Yasuko [Department of Dental and Biomedical Materials Science, Unit of Basic Medical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588 (Japan); Miura, Eri [Department of Dental and Biomedical Materials Science, Unit of Basic Medical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588 (Japan); Fujita, Takeshi [Department of Dental and Biomedical Materials Science, Unit of Basic Medical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588 (Japan); Hisatsune, Kunihiro [Department of Dental and Biomedical Materials Science, Unit of Basic Medical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588 (Japan)

2007-06-15

The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au-Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au-Pt-X (X = In, Sn, Fe, Zn) and quaternary Au-Pt-In-Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au-10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C *. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au-Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L *, and the addition of Sn gave a very light tint of red to the parent alloy. Although red-green chromaticity index a * contributed to chroma to some extent, contribution of yellow-blue chromaticity index b * was much greater in determining chroma in this Pd-free Au-Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au-Pt-based high noble dental alloys.

Degradable and porous Fe-Mn-C alloy for biomaterials candidate

Science.gov (United States)

Pratesa, Yudha; Harjanto, Sri; Larasati, Almira; Suharno, Bambang; Ariati, Myrna

2018-02-01

Nowadays, degradable implants attract attention to be developed because it can improve the quality of life of patients. The degradable implant is expected to degrade easily in the body until the bone healing process already achieved. However, there is limited material that could be used as a degradable implant, polymer, magnesium, and iron. In the previous study, Fe-Mn-C alloys had succesfully produced austenitic phase. However, the weakness of the alloy is degradation rate of materials was considered below the expectation. This study aimed to produce porous Fe-Mn-C materials to improve degradation rate and reduce the density of alloy without losing it non-magnetic properties. Potassium carbonate (K2CO3) were chosen as filler material to produce foam structure by sintering and dissolution process. Multisteps sintering process under argon gas environment was performed to generate austenite phase. The product showed an increment of the degradation rate of the foamed Fe-Mn-C alloy compared with the solid Fe-Mn-C alloy without losing the Austenitic Structure

Structure and transformation behaviour of a rapidly solidified Al-Y-Ni-Co-Pd alloy

International Nuclear Information System (INIS)

Louzguine-Luzgin, D.V.; Inoue, A.

2005-01-01

An as-solidified structure and transformation behaviour on heating of the rapidly solidified Al-Y-Ni-Co-Pd alloy was studied by X-ray diffractometry (XRD), transmission electron microscopy (TEM), differential scanning and isothermal calorimetries. The Al-Y-Ni-Co-Pd ribbon samples have been produced by the melt spinning technique and heat treated using a differential scanning calorimeter (DSC). The addition of Pd to Al-Y-Ni-Co alloys caused disappearance of the supercooled liquid region as well as the formation of the highly dispersed primary α-Al nanoparticles about 3-7 nm in size homogeneously embedded in the glassy matrix upon solidification. An extremely high density of precipitates of the order of 10 24 m -3 is obtained. These particles start growing at the temperature below a glass-transition temperature. The results presented in this paper indicate that some of so-called 'marginal' glass-formers in as-solidified state are actually not glassy alloys with pre-existed nuclei but crystal-glassy nanocomposites

HRTEM study of the nanocrystalline Al85Y10Ni5 alloy

International Nuclear Information System (INIS)

Kozubowski, J.A.; Latuch, J.

1999-01-01

Nanocrystalline alloy Al 85 Y 10 Ni 5 obtained by annealing of the amorphous ribbons formed by melt spinning was studied by transmission electron microscopy and energy dispersive X-ray spectroscopy (EDS). The combined use of electron diffraction, electron microscopy and EDS has revealed the presence of several nano-phases: separate grains of Al(Y) and Al(N) solid solutions Al 3 Y grains and an unidentified phase of composition close to Al 3 (Ni,Y). (author)

HAYNES 244 alloy – a new 760 ∘C capable low thermal expansion alloy

Directory of Open Access Journals (Sweden)

Fahrmann Michael G.

2014-01-01

Full Text Available HAYNES® 244TM alloy is a new 760∘C capable, high strength low thermal expansion (CTE alloy. Its nominal chemical composition in weight percent is Ni – 8 Cr – 22.5 Mo – 6 W. Recently, a first mill-scale heat of 244 alloy was melted by Haynes International, and processed to various product forms such as re-forge billet, plate, and sheet. This paper presents key attributes of this new alloy (CTE, strength, low-cycle fatigue performance, oxidation resistance, thermal stability as they pertain to the intended use in rings and seals of advanced gas turbines.

Microstructure and mechanical properties of Mg-Zn-Y alloy containing LPSO phase and I-phase

Science.gov (United States)

Ye, Zhijian; Teng, Xinying; Lou, Gui; Zhou, Guorong; Leng, Jinfeng

2017-08-01

Microstructure and mechanical properties of Mg-Zn-Y alloy including LPSO phase and I-phase was investigated. Transmission electron microscopy, x-ray diffraction analysis and differential scanning calorimeter analysis reveal that the LPSO (long period stacking ordered structure) phase and I-phase can co-exist within the α-Mg matrix. Wherein, the quasicrystal phases exist in the (I-phase  +  α-Mg) eutectic structures. In the Mg-Zn-Y alloy, it is also found that 14 H type LPSO phases consist of LPSO phase and I-phase. With the addition of quasicrystal master alloy content, the microstructures are refined, and the mechanical properties are enhanced.

Structure and stacking faults in layered Mg-Zn-Y alloys: A first-principles study

International Nuclear Information System (INIS)

Datta, Aditi; Waghmare, U.V.; Ramamurty, U.

2008-01-01

We use first-principles density functional theory total energy calculations based on pseudo-potentials and plane-wave basis to assess stability of the periodic structures with different stacking sequences in Mg-Zn-Y alloys. For pure Mg, we find that the 6-layer (6l) structure with the ABACAB stacking is most stable after the lowest energy hcp (2l) structure with ABAB stacking. Addition of 2 at.% Y leads to stabilization of the structure to 6l sequence whereas the addition of 2 at.% Zn makes the 6l energetically comparable to that of the hcp. Stacking fault (SF) on the basal plane of 6l structure is higher in energy than that of the hcp 2l Mg, which further increases upon Y doping and decreases significantly with Zn doping. SF energy surface for the prismatic slip indicates activation of non-basal slip in alloys with a 6l structure. Charge density analysis shows that the 2l and 6l structures are electronically similar which might be a cause for better stability of 6l structure over a 4l sequence or other periodic structures. Thus, in an Mg-Zn-Y alloy, Y stabilizes the long periodicity, while its mechanical properties are further improved due to Zn doping

Fabrication of lithium/C-103 alloy heat pipes for sharp leading edge cooling

Science.gov (United States)

Ai, Bangcheng; Chen, Siyuan; Yu, Jijun; Lu, Qin; Han, Hantao; Hu, Longfei

2018-05-01

In this study, lithium/C-103 alloys heat pipes are proposed for sharp leading edge cooling. Three models of lithium/C-103 alloy heat pipes were fabricated. And their startup properties were tested by radiant heat tests and aerothermal tests. It is found that the startup temperature of lithium heat pipe was about 860 °C. At 1000 °C radiant heat tests, the operating temperature of lithium/C-103 alloy heat pipe is lower than 860 °C. Thus, startup failure occurs. At 1100 °C radiant heat tests and aerothermal tests, the operating temperature of lithium/C-103 alloy heat pipe is higher than 860 °C, and the heat pipe starts up successfully. The startup of lithium/C-103 alloy heat pipe decreases the leading edge temperature effectively, which endows itself good ablation resistance. After radiant heat tests and aerothermal tests, all the heat pipe models are severely oxidized because of the C-103 poor oxidation resistance. Therefore, protective coatings are required for further applications of lithium/C-103 alloy heat pipes.

Effect of the third element on the structure of liquid Mg{sub 65}Cu{sub 25}Y{sub 10} alloy

Energy Technology Data Exchange (ETDEWEB)

Liu, Dan [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061 (China); Weihai Wanfeng Magnesium Industry Science and Technology Development Co. Ltd., Weihai 264209 (China); Zhu, Xun Ming [Weihai Wanfeng Magnesium Industry Science and Technology Development Co. Ltd., Weihai 264209 (China); Qin, Jing Yu, E-mail: qinjy@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061 (China); Duan, Jun Peng; Wang, Ai Min [Weihai Wanfeng Magnesium Industry Science and Technology Development Co. Ltd., Weihai 264209 (China); Gu, Ting Kun [School of Electrical Engineering, Shandong University, Jinan 250061 (China)

2016-08-12

The liquid structures of Mg{sub 65}Cu{sub 25}Y{sub 10} and its three homologous binary liquid alloys are investigated via ab initio molecular dynamics in the present work. The chemical and topological environments in all four liquid alloys are analyzed using pair distribution function, coordination number, and the Voronoi polyhedron. It shows that the Cu atoms play significant role in deciding the chemical and topological short-range orders of the Mg{sub 65}Cu{sub 25}Y{sub 10} liquid alloy. The Voronoi polyhedra in the ternary liquid alloy illustrate less varieties and longer lifetime. Moreover, the diffusion coefficients are decreased significantly in the ternary liquid alloys according to the mean square displacements. All above offer a deeper insight into how the three species work in the Mg{sub 65}Cu{sub 25}Y{sub 10} liquid alloy. - Highlights: • Cu plays crucial role in Mg{sub 65}Cu{sub 25}Y{sub 10}'s chemical and topological SROs. • Additive elements decrease varieties and prolong lifetimes of Voronoi polyhedra. • Additive elements hinder the diffusion of Mg and Y efficiently.

Interdiffusion among U-Mo-Zr and alloys of Al to 550oC

International Nuclear Information System (INIS)

Komar Varela, C.L; Arico, S.F; Gribaudo, L.M

2006-01-01

The international community, by means of the project 'Reduced Enrichment for Research and Test Reactors' is interested in the development of a new nuclear fuel of very high density of uranium and low enrichment (≤ 20% de U 235 ) for reactors of investigation and production of radioisotopes, that permit to reach greater neutron flows, with good capacity to be reprocessed One of these assemblies are the alloys of U with Mo contents between 7 and 10% in weight. In the fuels 'dispersed type plate' the particles of U-Mo are mixed with dust of aluminum and are co - laminated between two plates of an alloy of the same material. The existing contact among the particles permits the interdiffusion of the materials with the consequent apparition of new phases. Studies pursuit-irradiation have shown a badly behavior of these new phases. It is for this that is necessary to control the presence of these products of interaction. The aggregate of a third element to the alloys U - Mo has begun to be practiced with this purpose. In this work the modification of the start of the disorder of the phase γU in the alloy U-7%Mo-1%Zr was studied and the interdiffusion between pure aluminum and the same alloy to 550 o C. The results obtained are compared with other obtained for peers U-Mo/Al. The techniques of characterization utilized were: optical microscopy, analysis by diffraction of X-rays and microanalysis quantitative by microprobe electronic. It was observed that the aggregate of Zr refines the grain for a processing of homogenized in composition of Mo to 1000 o C and accelerates the start of the disorder of the phase γU to 550 o C. As for the zone of interaction, was found that the composed identifying do not they differ to them reported in the in peers U-Mo/Al. These are: (U,Mo)Al 4 y UAl 3 (AG)

Effect of performance of Zr-Y alloy target on thin film deposition technology

International Nuclear Information System (INIS)

Pan Qianfu; Liu Chaohong; Jiang Mingzhong; Yin Changgeng

2011-01-01

Yttria-stabilized zirconia (YSZ) films are synthesized on corrosion resistant plates by pulsed bias arc ion plating. The arc starting performance and the stability of thin film deposition is explored by improving the uniformity and compactibility of Zr-Y alloy target. The property of Zr-Y alloy target and depositional thin films were measured with the optical microscope, scanning electron microscope, X-ray diffractometer. The result shows that the target with hot rolling and annealing has a good arc starting performance and stability of thin film deposition, and the depositional thin films made of Yttria and amorphous zirconia are homogeneous and compact. (authors)

The adaptation of limb kinematics to increasing walking speeds in freely moving mice 129/Sv and C57BL/6.

Science.gov (United States)

Serradj, Nadjet; Jamon, Marc

2009-07-19

The kinematics of locomotion was analyzed in two strains of great importance for the creation of mutated mice (C56BL/6 and 129/Sv). Different behavioral situations were used to trigger sequences of movement covering the whole range of velocities in the mice, and the variations of kinematic parameters were analyzed in relation with velocity. Both stride frequency and stride length contributed to the moving speed, but stride frequency was found to be the main contributor to the speed increase. A trot-gallop transition was detected at speed about 70 cm/s, in relation with a sharp shift in limb coordination. The results of this study were consistent with pieces of information previously published concerning the gait analyses of other strains, and provided an integrative view of the basic motor pattern of mice. On the other hand some qualitative differences were found in the movement characteristics of the two strains. The stride frequency showed a higher contribution to speed in 129/Sv than in C57BL/6. In addition, 129/Sv showed a phase shift in the forelimb and hindlimb, and a different position of the foot during the stance time that revealed a different gait and body position during walking. Overall, 129/Sv moved at a slower speed than C57BL/6 in any behavioral situation. This difference was related to a basal lower level of motor activity. The possibility that an alteration in the dopamine circuit was responsible for the different movement pattern in 129/Sv is discussed.

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.)

129Xe on the outgassing of the atmosphere

International Nuclear Information System (INIS)

Thomsen, L.

1980-01-01

Because of the short half-life of its parent ( 129 I, 17 m.y.) and its own chemical inertness, 129 Xe offers unique insight into the problem of the outgassing history of the earth's atmosphere. Because the current atmosphere is different in Xe isotopic patterns than is the interior, the present atmosphere must have been largely outgassed before these patterns finished changing, that is, very early in earth history. Furthermore, there can have been no significant delay in the onset of outgassing; that is, the earth must have been initially hot. Because ancient sedimentary rocks indicate that the atmospheric Xe patterns have not changed substantially for over 3 b.y., models presuming a separate, lower mantle reservoir do not alter these conclusions. Similar conclusions have been reached before but have always carried a heavier burden of debatable assumptions

Crystallisation kinetics of amorphous Fe{sub 72.5-x}Cu{sub 1}Nb{sub 4.5}Si{sub 10+x+y}B{sub 12-y} alloy

Energy Technology Data Exchange (ETDEWEB)

Miglierini, M. [Komenskeho Univ., Bratislava (Czechoslovakia). Dept. of Nuclear Physics and Technics; Lipka, J. [Komenskeho Univ., Bratislava (Czechoslovakia). Dept. of Nuclear Physics and Technics; Sitek, J. [Komenskeho Univ., Bratislava (Czechoslovakia). Dept. of Nuclear Physics and Technics

1994-11-01

Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} and Fe{sub 72.5-x}Cu{sub 1}Nb{sub 4.5}Si{sub 10+x+y}B{sub 12-y} alloys are compared from the point of view of crystallisation behaviour and changes in the short-range order in the amorphous reminder. The increase in Nb to 4.5 at.% in the latter system slows down the formation of nanocrystals to approximately 40% even after 16 hours of anneal at 550 C for x = 0.5, y = 3. Segregation-induced changes in the short-range order are manifested via hyperfine field distributions corresponding to the amorphous reminder. (orig.)

Interdiffusion between U-Mo alloys and Al or Al alloys at 340 deg. C. Irradiation plan

International Nuclear Information System (INIS)

Fortis, A.M.; Mirandou, M.; Ortiz, M.; Balart, S.; Denis, A.; Moglioni, A.; Cabot, P.

2005-01-01

Out of reactor interdiffusion experiments between U-Mo alloys and Al alloys made close to fuel operation temperature are needed to validate the results obtained above 500 deg. C. A study of interdiffusion between U-Mo and Al or Al alloys, out and in reactor, has been initiated. The objective is to characterize the interdiffusion layer around 250 deg. C and study the influence of neutron irradiation. Irradiation experiments will be performed in the Argentine RA3 reactor and chemical diffusion couples will be fabricated by Friction Stir Welding (FSW) technique. In this work out-of-pile diffusion experiments performed at 340 deg. C are presented. Friction Stir Welding (FSW) was used to fabricate some of the samples. One of the results is the presence of Si, in the interaction layer, coming from the Al alloy. This is promising in the sense that the absence of Al rich phases may also be expected at low temperature. (author)

Steam Oxidation Behavior of Alloy 617 at 900 °C to 1100 °C

Science.gov (United States)

Liang, Zhiyuan; Wang, Yungang; Zhao, Qinxin

2018-05-01

The steam oxidation behavior of solid solution strengthened alloy 617 at 900 °C-1100 °C was investigated. The oxidation products were characterized by scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy. The results show that the oxidation kinetics of alloy 617 in steam followed the parabolic oxidation law. The calculated activity energy of alloy 617 was 223.47 kJ/mol. The oxidation products were mainly composed of external and internal scales and prior oxides at grain boundaries. External oxide scales were MnCr2O4, TiO2, and Cr2O3. Internal oxidation scales and prior oxides were Al2O3 and some Cr2O3 dissolved into Al2O3. The growth mechanism of oxide scales on alloy 617 is proposed.

Stability of Cd_1_–_xZn_xO_yS_1_–_y Quaternary Alloys Assessed with First-Principles Calculations

International Nuclear Information System (INIS)

Varley, Joel B.; He, Xiaoqing; Rockett, Angus; Lordi, Vincenzo

2017-01-01

One route to decreasing the absorption in CdS buffer layers in Cu(In,Ga)Se_2 and Cu_2ZnSn(S,Se)_4 thin-film photovoltaics is by alloying. Here we use first-principles calculations based on hybrid functionals to assess the energetics and stability of quaternary Cd, Zn, O, and S (Cd_1_–_xZn_xO_yS_1_–_y) alloys within a regular solution model. Our results identify that full miscibility of most Cd_1_–_xZn_xO_yS_1_–_y compositions and even binaries like Zn(O,S) is outside typical photovoltaic processing conditions. Finally, the results suggest that the tendency for phase separation of the oxysulfides may drive the nucleation of other phases such as sulfates that have been increasingly observed in oxygenated CdS and ZnS.

A FeNiMnC alloy with strain glass transition

Directory of Open Access Journals (Sweden)

Hui Ma

2018-02-01

Full Text Available Recent experimental and theoretical investigations suggested that doping sufficient point defects into a normal ferroelastic/martensitic alloy systems could lead to a frozen disordered state of local lattice strains (nanomartensite domains, thereby suppressing the long-range strain-ordering martensitic transition. In this study, we attempt to explore the possibility of developing novel ferrous Elinvar alloys by replacing nickel with carbon and manganese as dopant species. A nominal Fe89Ni5Mn4.6C1.4 alloy was prepared by argon arc melting, and XRD, DSC, DMA and TEM techniques were employed to characterize the strain glass transition signatures, such as invariance in average structure, frequency dispersion in dynamic mechanical properties (storage modulus and internal friction and the formation of nanosized strain domains. It is indicated that doping of Ni, Mn and C suppresses γ→α long-range strain-ordering martensitic transformation in Fe89Ni5Mn4.6C1.4 alloy, generating randomly distributed nanosized domains by strain glass transition. Keywords: Strain glass transition, Elinvar alloys, Point defects, Nanosized domains

Positron annihilation characterization of nanostructured ferritic alloys

International Nuclear Information System (INIS)

Alinger, M.J.; Glade, S.C.; Wirth, B.D.; Odette, G.R.; Toyama, T.; Nagai, Y.; Hasegawa, M.

2009-01-01

Nanostructured ferritic alloys (NFAs) were produced by mechanically alloying Fe-14Cr-3W-0.4Ti and 0.25Y 2 O 3 (wt%) powders followed by hot isostatic pressing consolidation at 850, 1000 and 1150 deg. C. Positron annihilation lifetime and orbital momentum spectroscopy measurements are in qualitative agreement with small angle neutron scattering, transmission electron microscopy and atom probe tomography observations, indicating that up to 50% of the annihilations occur at high densities of Y-Ti-O enriched nm-scale features (NFs). Some annihilations may also occur in small cavities. In Y-free control alloys, that do not contain NFs, positrons primarily annihilate in the Fe-Cr matrix and at features such as dislocations, while a small fraction annihilate in large cavities or Ar bubbles.

Y and Er minor addition effect on glass forming ability of a Ni–Nb–Zr alloy

International Nuclear Information System (INIS)

Deo, L.P.; Oliveira, M.F. de

2015-01-01

Highlights: • A theoretical selection criterion to predict the GFA was used for Ni–Nb–Zr–RE alloys. • The prediction agrees very well with thermal parameter gm used to evaluate experimentally the GFA. • RE doped alloys showed higher GFA than the base alloy. • Y and Er elements showed similar effects to improve the GFA of the base alloy. - Abstract: Since the discovering of amorphous alloys in 1960, the actual causes of why some alloys can be easily formed into glasses while others cannot, are not clearly known, thus there is no universal theory to predict the glass forming ability in metallic systems. It is well known that the minor amount addition of proper rare-earth elements can greatly enhance the glass forming ability of some glass-forming alloys. In the present study, a selection criterion was successfully used to predict the glass forming ability improvement of Ni 67.3 Nb 28.4 Zr 4.3 alloy with minor additions of Y or Er. The actual glass forming ability of the base alloy and rare-earth doped alloys were evaluated by the thermal parameter γ m and the results agree very well with the tendency predicted by the calculation. The amorphous nature of alloys was mainly analyzed by X-ray diffraction and differential scanning calorimetry. This work also presents a brief and complementary consideration about oxygen contamination quantified by the inert gas fusion method

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.

Micro-alloying Mg with Y, Ce, Gd and La for texture modification-A comparative study

International Nuclear Information System (INIS)

Stanford, N.

2010-01-01

A comparative study of the effectiveness of Y, La, Ce and Gd as texture modifiers during the extrusion of magnesium-based alloys has been carried out. It was found that La, Ce and Gd are all effective texture modifiers, being able to produce the 'rare earth' texture at the low alloying levels of 300, 400 and 600 ppm respectively. Y was not as effective as the other three elements in modifying the texture, and at no concentration studied did this element form a typical 'rare earth' texture. It is proposed that a strong interaction of solutes with dislocations and grain boundaries is responsible for the significant impact rare earth additions have on the extruded grain size and texture at very low alloying levels.

Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

Science.gov (United States)

Shen, H. H.; Liu, L.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

2016-12-01

The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

Note: Durability analysis of optical fiber hydrogen sensor based on Pd-Y alloy film.

Science.gov (United States)

Huang, Peng-cheng; Chen, You-ping; Zhang, Gang; Song, Han; Liu, Yi

2016-02-01

The Pd-Y alloy sensing film has an excellent property for hydrogen detection, but just for one month, the sensing film's property decreases seriously. To study the failure of the sensing film, the XPS spectra analysis was used to explore the chemical content of the Pd-Y alloy film, and analysis results demonstrate that the yttrium was oxidized. The paper presented that such an oxidized process was the potential reason of the failure of the sensing film. By understanding the reason of the failure of the sensing film better, we could improve the manufacturing process to enhance the property of hydrogen sensor.

Effects in Mg-Zn-based alloys strengthened by quasicrystalline phase

International Nuclear Information System (INIS)

Vlček, M; Čížek, J; Lukáč, F; Melikhova, O; Hruška, P; Procházka, I; Vlach, M; Stulíková, I; Smola, B; Jäger, A

2016-01-01

Magnesium Mg-based alloys are promising lightweight structural materials for automotive, aerospace and biomedical applications. Recently Mg-Zn-Y system attracted a great attention due to a stable icosahedral phase (I-phase) with quasicrystalline structure which is formed in these alloys. Positron lifetime spectroscopy and in situ synchrotron X-ray diffraction were used to study thermal stability of I-phase and precipitation effects in Mg-Zn-Y and Mg- Zn-Al alloys. All alloys containing quasicrystalline I-phase exhibit misfit defects characterized by positron lifetime of ∼ 300 ps. These defects are associated with the interfaces between I- phase particles and Mg matrix. The quasicrystalline I-phase particles were found to be stable up to temperatures as high as ∼ 370°C. The W-phase is more stable and melts at ∼ 420°C. Concentration of defects associated with I-phase decreases after annealing at temperatures above ∼ 300°C. (paper)

Effect of substitution of 1 at% Ni for Zn on the microstructure and mechanical properties of Mg{sub 94}Y{sub 4}Zn{sub 2} alloy

Energy Technology Data Exchange (ETDEWEB)

Liu, Huan, E-mail: liuhuanseu@hotmail.com [Jiangsu Key Lab of Advanced Metallic Materials, School of Material Science and Engineering, Southeast University, Nanjing 211189 (China); Xue, Feng, E-mail: xuefeng@seu.edu.cn [Jiangsu Key Lab of Advanced Metallic Materials, School of Material Science and Engineering, Southeast University, Nanjing 211189 (China); Bai, Jing; Zhou, Jian [Jiangsu Key Lab of Advanced Metallic Materials, School of Material Science and Engineering, Southeast University, Nanjing 211189 (China); Liu, Xiaodao [Nanjing Yunhai Special Metals Co., Ltd., Nanjing 211200 (China)

2013-11-15

The microstructure and mechanical properties of Mg{sub 94}Y{sub 4}Zn{sub 2} and Mg{sub 94}Y{sub 4}Zn{sub 1}Ni{sub 1} alloys have been systematically investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and an electronic universal testing machine. The as-cast WZ42 alloy is composed of α-Mg matrix, 18R LPSO (long period stacking ordered) phase and a small fraction of Mg{sub 24}(Y,Zn){sub 5} phases. With the replacement of 1 at% Ni atoms, the phase structures in WZN411 alloy remain unchanged, but their chemical compositions vary obviously. A great number of stacking faults exist in α-Mg grains of WZ42 alloy, while they are barely observed in WZN411 alloy. After annealing at 500 °C for 12 h, there are plenty of 14H LPSO lamellas formed in WZ42 alloy and many nano-scale α-Mg slices generated between 18R phases. In contrast, the 18R in WZN411 alloy is thermally stable, and both the formation of α-Mg slices and 14H lamellas are restricted for annealed WZN411 alloy. Tensile tests indicate that the as-extruded WZ42 alloy exhibits ultimate tensile strength of 390 MPa, tensile yield strength of 246 MPa and elongation of 2.8% at room temperature. With the replacement of 1 at% Ni, the UTS and TYS of WZN411 alloy increase by 20 MPa and the ductility improves as well. The improvement of comprehensive mechanical properties could be ascribed to the substitution of 1 at% Ni element, which could enhance the degree of solid-solution strengthening and stimulate the thermal stability of 18R phase during annealing and extrusion processes.

Localized corrosion of alloys C-276 and 625 in aerated sodium chloride solutions at 25 to 200 degrees C

International Nuclear Information System (INIS)

Postlethwaite, J.

1991-12-01

Two molybdenum-bearing nickel alloys, Alloy C-276 and Alloy 625, were previously identified for consideration as candidate container materials for the Canadian Nuclear Fuel Waste Management Program. Because of the paucity of data for the localized corrosion behaviour of these passive alloys under conditions that may be experienced in a disposal vault, this project was undertaken to study the crevice and pitting corrosion of Alloys C-276 and 625 in chloride solutions at elevated temperatures. Electrochemical and immersion tests have been conducted in neutral sodium chloride solutions (0.1 wt% to saturated) at 25 to 200 degrees C, in an attempt to identify the conditions under which localized corrosion occurs and to relate the actual corrosion behaviour to that expected on the basis of electrochemical studies. Cyclic polarization studies showed that the passivation breakdown potentials move rapidly to more active values with increasing temperatures. Above 100 degrees C the resistance to localized corrosion is greatly reduced. The results of the immersion tests are presented in the form of T versus (C1-) diagrams. These susceptibility diagrams suggest that there is a limiting crevice-corrosion temperature for each alloy in aerated, neutral sodium chloride solutions. Below this temperature corrosion does not occur, regardless of the chloride concentration. The values of the limiting crevice-corrosion temperatures were in the range 100 to 125 degrees C for Alloy C-276 and 100 to 115 degrees C for Alloy 625. Such values suggest that saturation of the chloride solutions by surface boiling could occur without the initiation of localized corrosion. These electrochemical results indicate that a large safety margin for susceptibility to localized corrosion might be found below 100 degrees C

Determination of 129I in radioactive wastes

International Nuclear Information System (INIS)

Horvathova, B.; Dulanska, S.; Matel, L.; Remenec, B.; Gardonova, V.

2015-01-01

The goal of this work was to develop and optimize the conditions for the distillation of iodine and its use for determination of 129 I on liquid scintillation spectrometer (LSC). An appropriate distillation apparatus for distillation of iodine was proposed by testing distillation apparatus. A method of cleaning of 129 I from present interferents , e.g. 14 C, 137 Cs, was tested on proposed simple distillation apparatus. High-purity fraction needed for the determination of 129 I was achieved by distillation on liquid scintillation spectrometer TRI CARB 2900TR from Perkin Elmer Company. Optimal energy window (0 - 80) keV was chosen to measure 129 I on liquid scintillation spectrometer. Ultima Gold TM AB was chosen as more appropriate scintillator by testing of two scintillation solutions. Optimized method for determining the 129 I was applied to real samples coming from Bohunice NPP. The combination of precipitation method and method of 129 I purification by distillation is easy and less time consuming separation method for the determination of 129 I compared to conventional methods of separation of 129 I, e.g. by liquid extraction. Measuring method on the LSC spectrometer represents a measurement with a higher detection efficiency (95%) as compared to measurement of low-energy X-ray radiation 129 I (29.6 keV) with X-ray detector Si (Li) 12155 SL with detection efficiency only (1-2)%.

X-ray study of rapidly cooled ribbons of Al-Cr-Zr and Al-Ni-Y-Cr-Zr alloys

International Nuclear Information System (INIS)

Betsofen, S.Ya.; Osintsev, O.E.; Lutsenko, A.N.; Konkevich, V.Yu.

2002-01-01

One investigated into phase composition, lattice spacing and structure of rapidly cooled 25-200 μm gauge strips made of Al-4,1Cr-3,2Zr and Al-1,5Cr-1,5Zr-4Ni-3Y alloys, wt. %, produced by melt spinning to a water-cooled copper disk. In Al-4,1Cr-3,2Zr alloy one detected intermetallic phases: Al 3 Zr and two Al 86 Cr 14 composition icosahedral phases apart from aluminium solid solution with 4.040-4.043 A lattice spacing. In Al-1,5Cr-1,5Zr-4Ni-3Y alloy one identified two Al 86 Cr 14 icosahedral phases and two AlNiY and Al 3 Y yttrium-containing ones, lattice spacing of aluminium solid solution was equal to 4.052-4.053 A [ru

Influence of Zr and nano-Y{sub 2}O{sub 3} additions on thermal stability and improved hardness in mechanically alloyed Fe base ferritic alloys

Energy Technology Data Exchange (ETDEWEB)

Kotan, Hasan, E-mail: hkotan@konya.edu.tr [Department of Metallurgical Engineering and Materials Science, Necmettin Erbakan University, Dere Aşıklar Mah. Demet Sokak, Meram, Konya 42140 (Turkey); Darling, Kris A. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Scattergood, Ronald O.; Koch, Carl C. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27695-7907 (United States)

2014-12-05

The motivation of this work was driven to improve the thermal stability in systems where polymorphic transformations can result in an additional driving force, upsetting the expected thermodynamic stability. In this study, Fe{sub 92}Ni{sub 8} alloys with Zr and nano-Y{sub 2}O{sub 3} additions were produced by ball milling and then annealed at high temperatures. Emphasis was placed on understanding the effects of dispersed nano-Y{sub 2}O{sub 3} particle additions and their effect on microstructural stability at and above the bcc-to-fcc transformation occurring at 700 °C in Fe–Ni systems. Results reveal that microstructural stability and hardness can be promoted by a combination of Zr and Y{sub 2}O{sub 3} additions, that being mostly effective for stability before and after phase transition, respectively. The mechanical strength of these alloys is achieved by a unique microstructure comprised a ultra-fine grain Fe base matrix, which contains dispersions of both nano-scale in-situ formed Zr base intermetallics and ex-situ added Y{sub 2}O{sub 3} secondary oxide phases. Both of these were found to be essential for a combination of high thermal stability and high mechanical strength properties. - Highlights: • Polymorphic transformations can limit the processing of nanostructured powders. • It causes a rapid grain growth and impairs the improved mechanical properties. • We aim to improve the hardness and thermal stability above the phase transformation. • Thermal stability is achieved by a combination of Zr and Y{sub 2}O{sub 3} additions. • Hardness is promoted by in-situ formed and ex-situ added secondary nano phases.

On the microstructural factors affecting creep resistance of die-cast Mg–La-rare earth (Nd, Y or Gd) alloys

Energy Technology Data Exchange (ETDEWEB)

Gavras, S. [Magnesium Innovation Centre, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, Geesthacht (Germany); Zhu, S.M. [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, Victoria 3053 (Australia); Nie, J.F. [Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); Gibson, M.A. [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, Victoria 3053 (Australia); Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); CSIRO Manufacturing, Clayton, Victoria 3168 (Australia); Easton, M.A. [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, Victoria 3053 (Australia)

2016-10-15

Creep properties of high-pressure die-cast Mg–La-RE (Nd, Y or Gd) alloys, varying in ternary RE additions and in different heat treatment conditions, have been investigated. Through the use of short-term solution treatments (1 h at 520 °C) it was shown that the continuous intermetallic phase present in the eutectic at grain boundaries became discontinuous. This effect, in combination with the likely removal of the localised region of supersaturated solute in solid solution near grain boundaries, reduced the creep resistance. When relatively high concentrations of ternary alloying additions were used, solid solution strengthening and precipitation hardening appeared to compensate for the negative effect of reduced grain boundary reinforcement. Microstructural investigation revealed that Nd-containing alloys had fewer and larger dynamic precipitates present in the α-Mg matrix following creep testing at 177 °C and 90 MPa. It was concluded that grain boundary reinforcement in combination with the thermal stability of the precipitates formed, which is ultimately related to the diffusivity of solute in solid solution, are also contributing factors to creep resistance.

Tensile properties of vanadium alloys irradiated at <430{degrees}C

Energy Technology Data Exchange (ETDEWEB)

Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

1997-08-01

Recent attention to vanadium alloys has focused on significant susceptibility to loss of work-hardening capability in irradiation experiments at <430{degrees}C. An evaluation of this phenomenon was conducted on V-Ti, V-Cr-Ti, and V-Ti-Si alloys irradiated in several conventional and helium-charging irradiation experiments in the FFTF-MOTA, HFIR, and EBR-II. Work hardening capability and uniform tensile elongation appear to vary strongly from alloy and heat to heat. A strong heat-to-heat variation has been observed in V-4Cr-4Ti alloys tested, i.e., a 500-kg heat (No. 832665), a 100-kg heat (VX-8), and a 30-kg heat (BL-47). The significant differences in susceptibility to loss of work-hardening capability from one heat to another are estimated to correspond to a difference of {approx}100{degrees}C or more in minimum allowable operating temperature (e.g., 450 versus 350{degrees}C).

Microstructure Evolution of Mg-Gd-Y-Zn-Zr Magnesium Alloy During Partial Remelting

Directory of Open Access Journals (Sweden)

Jianquan TAO

2014-12-01

Full Text Available The article deals with the research on the microstructure evolution of Mg-Gd-Y-Zn-Zr magnesium alloy through partial remelting process. It aims at finding out what effects the microstructure of semi-solid Mg-Gd-Y-Zn-Zr alloy will result in under different remelting temperatures and holding times. Based on the results, if to raise the remelting temperature and to prolong the holding time, the size of solid grain will tend to expand and its spheroidization degree also begins to show improvement. In addition, the grain shows tendency of coarsening when the holding time increases. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6483

Effect of heat treatments on the microstructure and mechanical properties of an extruded Mg{sub 95.5}Y{sub 3}Zn{sub 1.5} alloy

Energy Technology Data Exchange (ETDEWEB)

Liu, Huan; Xue, Feng, E-mail: xuefeng@seu.edu.cn; Bai, Jing; Sun, Yangshan

2013-11-15

The microstructure and mechanical properties of the extruded Mg{sub 95.5}Y{sub 3}Zn{sub 1.5} alloy under different heat treatment were systematically investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and an electronic universal testing machine. The results show that the as-extruded alloy is composed of 18R LPSO stripes and α-Mg matrix with stacking faults (SFs) in it. The fine 14H LPSO lamellas are formed in α-Mg matrix near the areas of SFs during solution treatment at 500 °C for 8 h. A great number of fine β′ phases are precipitated in the α-Mg matrix of T6-treated (aging of the T4-treated alloy at 225 °C for 24 h) and T5-treated (aging of the as-extruded alloy at 225 °C for 32 h) alloys. Moreover, the SFs which were first observed in extruded alloy are retained in T5-staged specimen, and exhibit a cross arrangement with β′ precipitates. The absence of 14H LPSO phase in T5-treated alloy indicates that the 14H structure cannot be formed during aging at 225 °C. Tensile tests reveal that the presence of 14H lamellas improves the ductility of the alloy, but decreases the strength, suggesting that the 18R LPSO stripes are more effective in strengthening the alloy than 14H LPSO lamellas. The T6-staged alloy exhibits superior comprehensive mechanical properties with ultimate tensile strength of 358 MPa, tensile yield strength of 226 MPa and elongation of 6.1% at room temperature.

Experimental study of the Cu–Ni–Y system at 700 °C using diffusion couples and key alloys

Energy Technology Data Exchange (ETDEWEB)

Mezbahul-Islam, Mohammad, E-mail: mmedraj@encs.concordia.ca [Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, Quebec, Montreal, Canada H3G 1M8 (Canada); Medraj, Mamoun [Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, Quebec, Montreal, Canada H3G 1M8 (Canada)

2013-06-05

Highlights: ► Isothermal section at 700 °C of the Cu–Ni–Y system has been constructed. ► Diffusion couple technique has been used to understand the phase relations. ► Complete mutual solubility between CuY{sup *}–NiY and Cu{sub 4}Y–Ni{sub 4}Y have been determined. ► Maximum ternary solubility of the binary compounds has been determined. -- Abstract: Two solid–solid diffusion couples and 29 key samples have been used to construct the isothermal section of the Cu–Ni–Y system at 700 °C. Phase relations and ternary solubility of the binary compounds have been determined using scanning electron microscopy (SEM), wave dispersive X-ray spectrometer (WDS) and X-ray diffraction (XRD) analysis. The isothermal section at 700 °C consists of two single-phase region, 21 two-phase regions and 10 three-phase regions. Two extended solid solutions, between CuY{sup *}–NiY and Cu{sub 4}Y–Ni{sub 4}Y have been determined. The maximum solubility of Ni in Cu{sub 2}Y, Cu{sub 7}Y{sub 2} and Cu{sub 6}Y has been found to be about 28, 7.5 and 3.9 at.% Ni, respectively. The solubility of Cu in NiY{sub 3}, Ni{sub 2}Y, Ni{sub 3}Y, Ni{sub 7}Y{sub 2}, Ni{sub 5}Y and Ni{sub 17}Y{sub 2} is about 12.04, 9.67, 25, 3.08, 75 and 37 at.%. Cu, respectively. The solubility of Y in fcc (Cu, Ni) phase is about 0.6 at.%.

Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y2O3 particles

International Nuclear Information System (INIS)

Genc, Aziz; Luetfi Ovecoglu, M.

2010-01-01

Research highlights: → Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. → Reinforcement of the selected Ni-W powders with WC and Y 2 O 3 particles and further MA together for 12 h. → There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. → Sintering of the developed composites and the characterization investigations of the sintered samples. → Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y 2 O 3 particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 o C for 1 h under Ar and H 2 gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

Anti-Invar properties and magnetic order in fcc Fe-Ni-C alloy

International Nuclear Information System (INIS)

Nadutov, V.M.; Kosintsev, S.G.; Svystunov, Ye.O.; Garamus, V.M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

2011-01-01

Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy, which demonstrates high values of thermal expansion coefficient (TEC) (15-21)x10 -6 K -1 accompanied by almost temperature-insensitive behavior in temperature range of 122-525 K. Alloying with carbon considerably expanded the low temperature range of anti-Invar behavior in fcc Fe-Ni-based alloy. The Curie temperature of the alloy T C =195 K was determined on measurements of temperature dependences of magnetic susceptibility and saturation magnetization. The Moessbauer and small-angle neutron scattering (SANS) experiments on the fcc Fe-25.3%Ni-(0.73-0.78)%C alloys with the varying temperatures below and above the Curie point and in external magnetic field of 1.5-5 T were conducted. Low value of the Debye temperature Θ D =180 K was estimated using the temperature dependence of the integral intensity of Moessbauer spectra for specified temperature range. The inequality B eff =(0.7-0.9)B ext was obtained in external field Moessbauer measurement that points to antiferromagnetically coupled Fe atoms, which have a tendency to align their spins perpendicular to B ext . Nano length scale magnetic inhomogeneities nearby and far above T C were revealed, which assumed that it is caused by mixed antiferromagnetically and ferromagnetically coupled Fe atom spins. The anti-Invar behavior of Fe-Ni-C alloy is explained in terms of evolution of magnetic order with changing temperature resulting from thermally varied interspin interaction and decreasing stiffness of interatomic bond. - Highlights: → Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy. → Carbon expanded the temperature range of anti-Invar behavior in Fe-Ni-based alloy. → Moessbauer data point to mixed interspin interaction and low the Dedye temperature. → The SANS experiments reveal nano length scale magnetic inhomogeneities ≤6 nm. → Anti-Invar behavior of Fe-Ni-C alloy explained by thermally varied magnetic order.

On the formation and stability of Y-Ti-O nanoparticles in ODS alloys

International Nuclear Information System (INIS)

Sundar, C.S.

2012-01-01

The thermal and radiation stability of Y-Ti-O nanoparticles in oxide dispersion strengthened steels is a topic of interest, given that these nanoparticles bestow the crucial high temperature creep strength, and these ferritic alloys are candidate materials for cladding and structural materials for fast and fusion reactors. In addition, there is also interest in obtaining a basic understanding of the various issues, such as the role of alloying element Ti, on the formation of uniform sized and small nanoparticles in these alloys that are formed using the powder metallurgy route of ball milling followed by consolidation using hot extrusion

High-temperature deformation of dispersion-strengthened Cu-Zr-Ti-C alloys

International Nuclear Information System (INIS)

Palma, Rodrigo H.; Sepulveda, Aquiles; Espinoza, Rodrigo; Dianez, M. Jesus; Criado, Jose M.; Sayagues, M. Jesus

2005-01-01

The hot mechanical behaviour and microstructure of Cu-5 vol.% TiC, Cu-5 vol.% ZrO 2 and Cu-2.5 vol.% TiC-2.5 vol.% ZrO 2 alloys prepared by reaction milling were studied. After a test of 1 h annealing at 1173 K, the Cu-5 vol.% ZrO 2 alloy presented the lower softening resistance to annealing, while the other two ones kept their initial room-temperature hardness (about 2 GPa). Hot-compression tests at 773 and 1123 K, at initial true strain rates of 0.85 x 10 -3 and 0.85 x 10 -4 s -1 were performed. The Cu-2.5 vol.% TiC-2.5 vol.% ZrO 2 and the Cu-5 vol.% ZrO 2 alloys were the strongest and softest materials, respectively. Moreover, by electron microscopy, nanometric TiC and micrometric particles were detected in the Cu-5 vol.% TiC and Cu-5 vol.% ZrO 2 alloys, respectively. A possible explanation for the observed behaviour of these materials is proposed. In the compression tests, it was also found that strain rate has a low effect on flow stress, as it has been previously observed by various authors in dispersion-strengthened alloys deformed at high temperatures

Magnetic regimes in amorphous Ni--Fe--P--B alloys

International Nuclear Information System (INIS)

Durand, J.

1976-10-01

A complete substitution of iron for nickel was obtained by splat-cooling in amorphous alloys of composition (Ni/sub 100-y/Fe/sub y/) 79 P 13 B 8 . Results of high-field magnetization (up to 70 kOe), ac and dc low-field susceptibility, Curie temperature, and resistivity measurements over a temperature range of 1.7 to 300 0 K are reported. The Ni 79 P 13 B 8 alloy is not ferromagnetic, but the magnetization behavior as a function of field and temperature is typically that of alloys in the critical concentration range for ferromagnetism. The Fe 79 P 13 B 8 alloy is ferromagnetic with a Curie temperature T/sub c/ of 616 0 K. For y = 1 at. percent, the Fe atoms are magnetic. The variation of the moment per Fe atom as a function of y is discussed. When y is increased, the Ni atoms are likely to be polarized progressively and the moment per Ni atom would be roughly constant for y equal to or greater than 30 at. percent. Various magnetic behaviors were defined as a function of the Fe content. The value of T/sub c/ reaches a maximum for y similarly ordered 90 at. percent and extrapolates to zero for y similarly ordered 7 at. percent. Alloys within the range 1 equal to or less than y equal to or less than 10 at. percent did not exhibit well-defined Curie transition, but sharp maxima in low-field susceptibility measurements were observed at T/sub M/. The value of T/sub M/ is proportional to y for 1 equal to or less than y equal to or less than 4 at. percent, as in classical spin-glass regimes. For 4 less than y equal to or less than 10 at. percent, the variation of T/sub M/ as a function of y implies a more complicated type of magnetic ordering (micromagnetism or superparamagnetism). Homogeneous ferromagnetic ordering emerges only for y greater than 10 at. percent. Results of resistivity measurements are discussed in relation to the magnetic properties of different regimes in the magnetic phase diagram. 6 figures, 2 tables

Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

Energy Technology Data Exchange (ETDEWEB)

Shen, H.H.; Liu, L.; Liu, X.Z.; Guo, Q.; Meng, T.X.; Wang, Z.X.; Yang, H.J.; Liu, X.P., E-mail: liuxiaoping@tyut.edu.cn

2016-12-01

Highlights: • A Zr/ZrC modified layer was formed on AISI 440B stainless steel using plasma surface Zr-alloying. • The thickness of the modified layer increases with alloying temperature and time. • Formation mechanism of the modified layer is dependent on the mutual diffusion of Zr and substrate elements. • The modified surface shows an improved wear resistance. - Abstract: The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

Evaluation of Sc-Bearing Aluminum Alloy C557 for Aerospace Applications

Science.gov (United States)

Domack, Marcia S.; Dicus, Dennis L.

2002-01-01

The performance of the Al-Mg-Sc alloy C557 was evaluated to assess its potential for a broad range of aerospace applications, including airframe and launch vehicle structures. Of specific interest were mechanical properties at anticipated service temperatures and thermal stability of the alloy. Performance was compared with conventional airframe aluminum alloys and with other emerging aluminum alloys developed for specific service environments. Mechanical properties and metallurgical structure were evaluated for commercially rolled sheet in the as-received H116 condition and after thermal exposures at 107 C. Metallurgical analyses were performed to de.ne grain morphology and texture, strengthening precipitates, and to assess the effect of thermal exposure.

Influence of S, P, C on grain boundary diffusion and creep properties of Alloy 800; Einfluss von S, P, C auf die Korngrenzendiffusion und Kriecheigenschaften von Alloy 800

Energy Technology Data Exchange (ETDEWEB)

Lindemann, J.; Hannesen, K.; Mast, R.; Viefhaus, H. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Grabke, H.J.

1998-12-31

The paper reports examinations of Alloy 800 and specific commercially available variants known under the names of 800H, 800HT, and 800LC, differing in their concentrations of C, Al, and Ti. In addition, melts also containing phosphorus (0.09 wt-%) or sulfur (0.04 wt-%) as additional alloying materials have been prepared for the experiments. The volume diffusion and the grain boundary diffusion of {sup 59}Fe in those alloys was measured at temperatures between 800 and 1000 C by means of a radioactive tracer method combined with residual activity measurements. It was found that accompanying elements like phosphorus and sulfur increase the activation energy of the grain boundary diffusion of the iron and thus delay the grain boundary self-diffusion in Alloy 800. Creep curves were measured of the same materials after age-hardening treatment for 100 hours at 800 C, measurements performed at constant temperature but at three different, constant creep stress loads. The results showed that addition of phosphorus markedly increases the lifetime of Alloy 800, and reduces the creep rupture strain. The minimum strain rate in Alloy 800 containing 0.09 wt-% of phosphorus was found to be lower by a factor of 100, as compared to the other Alloy 800 materials used. (orig./CB) [Deutsch] Alloy 800 ist ein austenitischer Fe-Ni-Cr Stahl, der relativ geringe, aber wichtige Konzentrationen von Kohlenstoff, Aluminium und Titan enthaelt. Besondere Varianten von Alloy 800, bekannt als 800H, 800HT und 800LC, unterscheiden sich in den Konzentrationen dieser Elemente. Diese kommerziellen Legierungen wurden untersucht, und zusaetzlich wurden Schmelzen mit zulegiertem Phosphor (0,09 Gew-%) bzw. Schwefel (0,04 Gew-%) hergestellt. Mittels einer radioaktiven Tracermethode in Verbindung mit Restaktivitaetsmessungen wurde die Volumen- und Korngrenzendiffusion von {sup 59}Fe in diesen Legierungen im Temperaturbereich 800-1000 C gemessen. Es wurde gefunden, dass Begleitelemente wie Phosphor und

Pd-Au/C catalysts with different alloying degrees for ethanol oxidation in alkaline media

International Nuclear Information System (INIS)

Qin, Yuan-Hang; Li, Yunfeng; Lv, Ren-Liang; Wang, Tie-Lin; Wang, Wei-Guo; Wang, Cun-Wen

2014-01-01

High alloyed Pd-Au/C catalyst is prepared through a rate-limiting strategy in water/ethylene glycol solution. Pd/C and low alloyed Pd-Au/C catalysts are prepared with trisodium citrate and sodium borohydride as stabilizing and reducing agents, respectively. Transmission electron microscopy (TEM) shows that the synthesized Pd(Au) particles are well dispersed on the catalysts. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) show that the high alloyed Pd-Au/C catalyst presents a relatively homogenous structure while the low alloyed Pd-Au/C catalyst presents a Pd-rich shell/Au-rich core structure. Electrochemical characterization shows that the low alloyed Pd-Au/C catalyst exhibits the best catalytic activity for ethanol oxidation reaction (EOR) in alkaline media, which could be attributed to its relatively large exposed Pd surface area as compared with the high alloyed Pd-Au/C catalyst due to its Pd-rich shell structure and its enhanced adsorption of OH ads as compared with Pd/C catalyst due to its core-shell structure

Morphology and the structure of quasicrystal phase in as-cast and melt-spun Mg-Zn-Y-Zr alloys

International Nuclear Information System (INIS)

Tang, Y.L.; Zhao, D.S.; Shen, N.F.

1993-01-01

During recent years, many researchers have investigated the experimental and theoretical aspects of quasicrystal materials. In some Mg alloys (Mg 32 Al 17 Zn 32 , Mg 32 (Al,Zn) 49 , Mg 32 (Al,Zn,Cu) 49 , Mg 4 CuAl 6 and Ga 16 Mg 32 Zn 52 ), icosahedral quasicrystals (IQC) have been found. However, most of the quasicrystals in these alloys were formed under a rapid solidification condition. In the recent study on Mg-Zn-(Zr,Y) as-cast alloys, the authors identified a new Mg-rich and a Zn-rich IQC by X-ray diffraction (XRD) and electron microscopy (EM). The discovery of Mg-Zn-Y IQC is of interest because it formed in an as-cast ingot and did not contain the element Al, which is the major constituent of nearly all IQC forming alloys reported. Also, analyses on IQC in as-cast and RS Mg alloys with the composition have not previously been carried out. In this paper, TEM and XRD investigations were completed on IQC formed in a Mg-Zn-Y-Zr cast ingot and melt-spun ribbons for microstructure comparison

Stability and migration of vacancy in V–4Cr–4Ti alloy: Effects of Al, Si, Y trace elements

International Nuclear Information System (INIS)

Zhang, Chong; Zhang, Pengbo; Li, Ruihuan; Zhao, Jijun; Dong, Chuang

2013-01-01

Addition of trace amounts of Al, Si and Y into V–4Cr–4Ti alloy is beneficial for the mechanical properties under irradiation. It is thus important to investigate the influence of solute/trace elements on stabilities, energetics and diffusion behaviors of vacancy defects. We performed first-principles calculations to evaluate vacancy–solute/trace interaction inside dilute V–X (X = Ti, Cr, Al, Si, Y) and V–4Cr–4Ti–(Al, Si, Y) alloys. With addition of Si and Y, vacancy-based complexes tend to form near Ti–Si and Ti–Y pairs, while the effect of Al is negligible. Moreover, diffusion coefficients of solute/trace element in vanadium were derived using nine-frequency model. With high binding energy and low diffusion coefficient, Si atom is strongly attractive to vacancy in vanadium matrix. Our theoretical results suggest that the interactions between vacancy and solute/trace elements play some role in the evolution of microstructures inside vanadium alloys

Single crystal studies of platinum alloys for oxygen reduction electrodes

DEFF Research Database (Denmark)

Ulrikkeholm, Elisabeth Therese

/Pt(111) in the following. The prepared alloys were investigate using Low Energy Electron Diffraction (LEED), Xray Photoelectron Spectroscopy (XPS), Ion Scattering Spectroscopy (ISS) and temperature Programmed Desorption (TPD). The LEED pattern indicated that the Y/Pt(111) sample had formed a 1...... peaks with a large shift towards lower temperatures. The change in desorption temperature was ∆T = −180°C for the Y/Pt(111) sample and ∆T = −200°C for the Gd/Pt(111) sample. The ORR activity was measured showing a large enhancement for both alloys. Angle resolved XPS performed on the samples after.......89×1.89 structure, and the Gd/Pt(111) sample has formed a 1.90×1.90 structure compared to pure platinum. From the XPS measurements, it is most likely that alloys with the Pt5Y and Pt5Gd stoichiometry have been formed. The reactivity of the surfaces were probed using TPD. These measurements showed sharp desorption...

Grain refinement of AZ91D magnesium alloy by a new Mg–50%Al4C3 master alloy

International Nuclear Information System (INIS)

Liu, Shengfa; Chen, Yang; Han, Hui

2015-01-01

A novel and simple method for preparing Mg–50%Al 4 C 3 (hereafter in wt.%) master alloy has been developed by powder in-situ synthesis process under argon atmosphere. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) results show the existence of Al 4 C 3 particles in this master alloy. After adding 1.8% Mg–50%Al 4 C 3 master alloy, the average grain size of α-Mg decreased from 360 μm to 154 μm. Based on the DTA test results and calculation of the planar disregistry between Al 4 C 3 and α-Mg, Al 4 C 3 particles located in the central regions of magnesium grains can act as the heterogeneous nucleus of primary α-Mg phase

Superconductivity in CeCu/sub 2/Si/sub 2/: dependence of Tsub(c) on alloying and stoichiometry

Energy Technology Data Exchange (ETDEWEB)

Spille, H; Rauchschwalbe, U; Steglich, F [Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Festkoerperphysik

1938-01-01

The authors have determined the transition temperatures of the alloy systems (Ce,M)Cu/sub 2/Si/sub 2/ with M = La, Y, Sc, Ce(Cu,T)/sub 2/Si/sub 2/ with T = Ag, Au, Mn, Ru, Rh, Pd and CeCu/sub 2/(Si,Ge)/sub 2/ as well as of CeCu/sub 2/Si/sub 2/ samples with varying stoichiometry. In each case, alloying is found to depress Tsub(c), the critical concentrations necessary to destroy superconductivity ranging between < 1 at.% and 10 at.%. Off-stoichiometry samples with a Cu- or Ce-deficiency of a few at.% are not superconducting, while samples prepared with a comparable excess of Cu or Ce show sharp transitions at Tsub(c) >approx. 600 mK. It is inferred that stoichiometric CeCu/sub 2/Si/sub 2/ contains substantial concentrations of Cu- and Ce-vacancies, which hinder superconductivity. First results on CeCu/sub 2/Si/sub 2/ single crystals, which exhibit bulk superconductivity, are also reported.

129I in the environment around a nuclear reprocessing plant

International Nuclear Information System (INIS)

Joshi, S.N.; Doshi, G.R.

1988-01-01

129 I and 131 I activities are measured in leaf samples collected within Trombay region, covering a radius of 4500 m from the reprocessing plant. The concentration of 129 I and 131 I in dried leaf samples ranged from 0.04 to 1.28 pCi/gm and 4 to 5 pCi/gm respectively. A radiochemical procedure involving distillation and solvent extractions of 129 I and then counting in a Liquid Scintillation Spectrometer is used for its final determination. The concentration of 129 I observed in leaf samples collected at the south site gate is used to calculate the dose commitment to an adult via grass-cow-milk pathway. On the basis of conservative assumption that the activity present in the grass would be equal to that in the leaf, the dose commitment to an adult through milk ingestion route will not exceed 5.5 μSv/y. (author). 2 tabs., 13 refs

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.

Electrochemical Behavior Assessment of As-Cast Mg-Y-RE-Zr Alloy in Phosphate Buffer Solutions (X Na3PO4 + Y Na2HPO4) Using Electrochemical Impedance Spectroscopy and Mott-Schottky Techniques

Science.gov (United States)

Fattah-alhosseini, Arash; Asgari, Hamed

2018-05-01

In the present study, electrochemical behavior of as-cast Mg-Y-RE-Zr alloy (RE: rare-earth alloying elements) was investigated using electrochemical tests in phosphate buffer solutions (X Na3PO4 + Y Na2HPO4). X-ray diffraction techniques and Scanning electron microscopy equipped with energy dispersive x-ray spectroscopy were used to investigate the microstructure and phases of the experimental alloy. Different electrochemical tests such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis were carried out in order to study the electrochemical behavior of the experimental alloy in phosphate buffer solutions. The PDP curves and EIS measurements indicated that the passive behavior of the as-cast Mg-Y-RE-Zr alloy in phosphate buffer solutions was weakened by an increase in the pH, which is related to formation of an imperfect and less protective passive layer on the alloy surface. The presence of the insoluble zirconium particles along with high number of intermetallic phases of RE elements mainly Mg24Y5 in the magnesium matrix can deteriorate the corrosion performance of the alloy by disrupting the protective passive layer that is formed at pH values over 11. These insoluble zirconium particles embedded in the matrix can detrimentally influence the passivation. The M-S analysis revealed that the formed passive layers on Mg-Y-RE-Zr alloy behaved as an n-type semiconductor. An increase in donor concentration accompanying solutions of higher alkalinity is thought to result in the formation of a less resistive passive layer.

Hot mechanical behaviour of dispersion strengthened Cu alloys

International Nuclear Information System (INIS)

Garcia G, Jose; Espinoza G, Rodrigo; Palma H, Rodrigo; Sepulveda O, Aquiles

2003-01-01

This work is part of a research project which objective is the improvement of the high-temperature mechanical properties of copper, without an important decrease of the electrical or thermal conduction properties. The general hypothesis is that this will be done by the incorporation of nanometric ceramic dispersoids for hindering the dislocation and grain boundaries movement. In this context, the object of the present work is the study of the resistance to hot deformation of dispersion-strengthened copper alloys which have prepared by reactive milling. Two different alloys, Cu-2,39wt.%Ti-0.56wt.%C and Cu-1.18wt.%Al, were prepared so as obtain a copper matrix reinforced with nanometric TiC y Al 2 O 3 particles with a nominal total amount of 5 vol.%. The particles were developed by an in-situ formation process during milling. The materials were prepared in an attritor mill, and consolidated by extrusion at 750 o C, with an area reduction rate of 10:1. The resistance to hot deformation was evaluated by hot compression tests at 500 and 850 o C, at initial strain rates of 10 -3 and 10 -4 s-1. To evaluate the material softening due temperature, annealing at 400, 650 y 900 o C during 1h were applied; after that, hardness was measured at room temperature. Both studies alloys presented a higher resistance to hot deformation than pure copper, with or without milling. Moreover, the Cu-Ti-C alloy presented a mechanical resistance higher than that of the Cu-Al one. Both alloys presented strain-stress compression curves with a typical hot-work shape: an initial maximum followed by a stationary plateau. The Cu-Ti-C alloy had a higher hardness and did not present a hardness decay even after annealings at the higher temperature imposed (900 o C), while the Cu-Al alloy did exhibit a strong decay of hardness after the annealing at 900 o C. The best behaviour exhibited by the Cu-Ti C alloy, was attributed to the formation of a major quantity of dispersoids that in the Cu-Al alloy. In

Helium sequestration at nanoparticle-matrix interfaces in helium + heavy ion irradiated nanostructured ferritic alloys

Energy Technology Data Exchange (ETDEWEB)

Parish, C.M., E-mail: parishcm@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Unocic, K.A.; Tan, L. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zinkle, S.J. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); University of Tennessee, Knoxville, TN 37996 (United States); Kondo, S. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011 (Japan); Snead, L.L. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hoelzer, D.T.; Katoh, Y. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2017-01-15

We irradiated four ferritic alloys with energetic Fe and He ions: one castable nanostructured alloy (CNA) containing Ti-W-Ta-carbides, and three nanostructured ferritic alloys (NFAs). The NFAs were: 9Cr containing Y-Ti-O nanoclusters, and two Fe-12Cr-5Al NFAs containing Y-Zr-O or Y-Hf-O clusters. All four were subjected to simultaneous dual-beam Fe + He ion implantation (650 °C, ∼50 dpa, ∼15 appm He/dpa), simulating fusion-reactor conditions. Examination using scanning/transmission electron microscopy (STEM) revealed high-number-density helium bubbles of ∼8 nm, ∼10{sup 21} m{sup −3} (CNA), and of ∼3 nm, 10{sup 23} m{sup −3} (NFAs). STEM combined with multivariate statistical analysis data mining suggests that the precipitate-matrix interfaces in all alloys survived ∼50 dpa at 650 °C and serve as effective helium trapping sites. All alloys appear viable structural material candidates for fusion or advanced fission energy systems. Among these developmental alloys the NFAs appear to sequester the helium into smaller bubbles and away from the grain boundaries more effectively than the early-generation CNA.

Structural and electronic properties of Ga{sub 1-x}In{sub x} As{sub 1-y}N{sub y} quaternary semiconductor alloy on GaAs substrate

Energy Technology Data Exchange (ETDEWEB)

Aslan, Metin, E-mail: maslan@sakarya.edu.tr [Sakarya University, Art, Science Faculty, Department of Physics, Esentepe Campus, 54187 Sakarya (Turkey); Yalc Latin-Small-Letter-Dotless-I n, Battal G.; Uestuendag, Mehmet [Sakarya University, Art, Science Faculty, Department of Physics, Esentepe Campus, 54187 Sakarya (Turkey)

2012-04-05

Highlights: Black-Right-Pointing-Pointer In this study we used DFT in the frame of LDA approach to determine electronic and structural properties of GaInAsN alloy. Black-Right-Pointing-Pointer We calculated lattice parameter and band gap energy of binary (GaAs, InAs, and GaN), ternary (GaInAs, GaAsN) and quaternary (GaInAsN) semiconductor alloys. Black-Right-Pointing-Pointer We formulated lattice parameter of GaInAsN respect to In and N composition. Black-Right-Pointing-Pointer We investigated different In and N composition of GaInAsN/GaAs heterostructure for various device applications. - Abstract: We have presented structural and electronic properties of binary (GaAs, GaN and InAs), ternary (Ga{sub 1-x}In{sub x}As and GaAs{sub 1-y}N{sub y}) and quaternary (Ga{sub 1-x}In{sub x}As{sub 1-y}N{sub y}) semiconductor alloys by using a first-principles pseudopotential technique. The structural and electronic properties of Zinc-Blende phase of these materials have been calculated by using the local density approximation (LDA) of the density-functional theory (DFT). To obtain the lattice parameter and band gap energy of the (GaInAsN) quaternary semiconductor alloy we separately calculated the lattice constant and band gap energies of ternary semiconductor alloys, namely GaAsN and GaInAs. The calculated lattice constant, bulk modulus and the direct band gaps for studied semiconductors showed great parallelism with the previous available theoretical and experimental studies.

Electronic band structure calculations for GaxIn1−xASyP1−y alloys lattice matched to InP

International Nuclear Information System (INIS)

Bechiri, A; Benmakhlouf, F; Allouache, H; Bacha, S; Bouarissa, N

2012-01-01

A pseudopotential formalism coupled with the virtual crystal approximation are applied to study the effect of compositional disorder upon electronic band structure of cubic Ga x In 1−x As y P 1−y quarternary alloys lattice matched to InP. The effects of compositional variations are properly included in the calculations. Very good agreement is obtained between the calculated values and the available experimental data for the lattice–matched alloy to InP. The absorption at the fundamental optical gaps is found to be direct within a whole range of the y composition whatever the lattice-matching to the substrate of interest. The alloy system Ga x In 1−x As y P 1−y lattice matched to InP is suggested to be suitable for an efficient light emitting device (ELED) material.

Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y{sub 2}O{sub 3} particles

Energy Technology Data Exchange (ETDEWEB)

Genc, Aziz, E-mail: agenc@itu.edu.t [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey); Luetfi Ovecoglu, M. [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey)

2010-10-15

Research highlights: {yields} Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. {yields} Reinforcement of the selected Ni-W powders with WC and Y{sub 2}O{sub 3} particles and further MA together for 12 h. {yields} There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. {yields} Sintering of the developed composites and the characterization investigations of the sintered samples. {yields} Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y{sub 2}O{sub 3} particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 {sup o}C for 1 h under Ar and H{sub 2} gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

Effects of Nd-addition on the structural, hydrogen storage, and electrochemical properties of C14 metal hydride alloys

Energy Technology Data Exchange (ETDEWEB)

Wong, D.F. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Young, K., E-mail: kwo.young@basf.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Nei, J.; Wang, L. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Ng, K.Y.S. [Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States)

2015-10-25

Nd-addition to the AB{sub 2}-based alloy Ti{sub 12}Zr{sub 22.8−x}V{sub 10}Cr{sub 7.5}Mn{sub 8.1}Co{sub 7.0}Ni{sub 32.2}Al{sub 0.4}Nd{sub x} is studied for its effects on the structure, gaseous-phase hydrogen storage, and electrochemical properties. This study follows a series of Cu, Mo, Fe, Y, Si, and La doping studies in similar AB{sub 2}-based alloys. Limited solubility of Nd in the main Laves phase promotes the formation of secondary phases (AB and Zr{sub 7}Ni{sub 10}) to provide catalytic effects and synergies for improved capacity and high-rate dischargeability (HRD) performance. The main C14 storage phase has smaller lattice constants and cell volumes, and these effects reduce the storage capacity at higher Nd levels. Different hydrogen absorption mechanisms can occur in these multi-component, multi-phase alloys depending on the interfaces of the phases, and they have effects on the alloy properties. Higher Nd-levels improve the HRD performance despite having lower bulk diffusion and surface exchange current. Magnetic susceptibility measurements indicate large percentage of larger metallic nickel clusters are present in the surface oxide of alloys with higher Nd-content, and AC impedance studies show very low charge-transfer resistance with high catalytic capability in the alloys. The −40 °C charge-transfer resistance of 8.9 Ω g in this Nd-series of alloys is the lowest measured out of the studies investigating doped AB{sub 2}-based MH alloys for improved low-temperature characteristics. The improvement in HRD and low-temperature performance appears to be related to the proportion of the highly catalytic NdNi-phase at the surface, which must offset the increased bulk diffusion resistance in the alloy. - Graphical abstract: Schematics of hydrogen flow and corresponding PCT isotherms in funneling mode. - Highlights: • Structural and hydrogen storage properties of Nd-substituted AB{sub 2} metal hydride are reported. • Nd contributes to the lowest

Surface Nb-ALLOYING on 0.4C-13Cr Stainless Steel: Microstructure and Tribological Behavior

Science.gov (United States)

Yu, Shengwang; You, Kai; Liu, Xiaozhen; Zhang, Yihui; Wang, Zhenxia; Liu, Xiaoping

2016-02-01

0.4C-13Cr stainless steel was alloyed with niobium using double glow plasma surface alloying and tribological properties of Nb-alloyed steel such as hardness, friction and wear were measured. Effects of the alloying temperature on microstructure and the tribological behavior of the alloyed steel were investigated compared with untreated steel. Formation mechanisms of Nb-alloyed layers and increased wear resistance were also studied. The result shows that after surface Nb-alloying treatment, the 0.4C-13Cr steel exhibits a diffusion adhesion at the alloyed layer/substrate interface and improved tribological property. The friction coefficient of Nb-alloyed steel is decreased by about 0.3-0.45 and the wear rate after Nb-alloying is only 2-5% of untreated steel.

The creep and intergranular cracking behavior of Ni-Cr-Fe-C alloys in 360 degree C water

International Nuclear Information System (INIS)

Angeliu, T.M.; Paraventi, D.J.; Was, G.S.

1995-01-01

Mechanical testing of controlled-purity Ni-xCr-9Fe-yC alloys at 360 C revealed an environmental enhancement in IG cracking and time-dependent deformation in high purity and primary water over that exhibited in argon. Dimples on the IG facets indicate a creep void nucleation and growth failure mode. IG cracking was primarily located at the interior of the specimen and not necessarily linked to direct contact with the environment. Controlled potential CERT experiments showed increases in IG cracking as the applied potential decreased, suggesting that hydrogen is detrimental to the mechanical properties. It is proposed that the environment, through the presence of hydrogen, enhances IG cracking by enhancing the matrix dislocation mobility. This is based on observations that dislocation-controlled creep controls the IG cracking of controlled-purity Ni-xCr-9Fe-yC in argon at 360 C and grain boundary cavitation and sliding results that show the environmental enhancement of the creep rate is primarily due to an increase in matrix plastic deformation. However, controlled potential CLT experiments did not exhibit a change in the creep rate as the applied potential decreased. While this does not clearly support hydrogen assisted creep, the material may already be saturated with hydrogen at these applied potentials and thus no effect was realized. Chromium and carbon decrease the IG cracking in high purity and primary water by increasing the creep resistance. The surface film does not play a significant role in the creep or IG cracking behavior under the conditions investigated

The synthesis and characterization of W- 1wt. % TiC alloy using a chemical method

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Hee; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

2016-05-15

Many studies have demonstrated the dispersed second phase nanoparticles in the tungsten matrix inhibit the grain growth and recrystallization, besides they improve the ductility and the irradiation resistance by hindering grain boundary sliding and stabilizing the microstructure.7 La{sub 2}O{sub 3}, Y{sub 2}O{sub 3}, TiC or ZrC particles are usually added to tungsten. However, some crucial issues should be solved such as the uniform distribution of these second phase particles and the industrial mass production. By using typical mechanical alloying and powder metallurgy, nanoparticles tend to be agglomerated and concentrated at the grain boundaries due to the high surface energies introduced. Moreover, the milling process often produces detrimental phase by the wear of the milling equipment and media. Xia et al. have firstly reported core-shell structured W/TiC using ammonium metatungstate ((NH{sub 4}){sub 6}W{sub 7}O{sub 24}·XH{sub 2}O, AMT) and hydrochloric acid. Nano-sized TiC particles are coated uniformly by AMT precipitation formed by the addition of hydrochloric acid to the AMT solution. The core-shell structure particles were examined by TEM. To achieve uniform distribution of TiC nanoparticles, a wet chemical method is essential rather than typical mechanical alloying. Also, the use of the chemical method of alloying can be easily applied to the industry with cost-effective and environmental benefits. The purpose of this study is to achieve uniform distribution of TiC nano-particles within the tungsten matrix, as the literature has studied. Moreover, the chemical methods could be applied to other refectory metals such as molybdenum. The obtained powder was reduced and sintered using SPS technique. The relative density of sintered sample achieved was 97%. Furthermore, the microstructure of the sintered sample was analyzed using FE-SEM and the presence of TiC particles at the grain boundary and grain interior was confirmed by EDS.

Influence of Rare Earth Elements on Microstructure and Mechanical Properties of Mg{sub 97}Zn{sub 1}Y{sub 1}RE{sub 1} Alloys

Energy Technology Data Exchange (ETDEWEB)

Kim, Jonghyun, E-mail: joindoc@kumamoto-u.ac.jp [Department of Material Science, Magnesium Research Center (MRC), Kumamoto University, Kumamoto, 860-8555 (Japan); Kawamura, Y. [Department of Material Science, Magnesium Research Center (MRC), Kumamoto University, Kumamoto, 860-8555 (Japan)

2013-06-20

Mg{sub 97}Zn{sub 1}Y{sub 1}RE{sub 1} (RE=La, Ce, Nd and Sm, at. %) alloys were prepared by high-frequency induction melting in an Ar atmosphere. Rods were extruded at 623 K and a ram speed of 2.5 mm·s{sup −1} using a circular die with an extrusion ratio of 10. The microstructure and mechanical properties of the extruded alloys were investigated. The Mg{sub 97}Zn{sub 1}Y{sub 1}Nd{sub 1} and Mg{sub 97}Zn{sub 1}Y{sub 1}Sm{sub 1} alloys consisted of only two phases: α-Mg and a Mg-RE intermetallic compound. The Mg{sub 97}Zn{sub 1}Y{sub 1}La{sub 1} and Mg{sub 97}Zn{sub 1}Y{sub 1}Ce{sub 1} alloys consisted of three phases: α-Mg, a Mg-RE intermetallic compound, and a Mg{sub 12}ZnY phase with a long-period stacking ordered (LPSO) phase. Additionally, after extrusion, the three-phase Mg{sub 97}Zn{sub 1}Y{sub 1}RE{sub 1} alloys, i.e., those with an LPSO phase, had a stratified microstructure and exhibited better mechanical properties than those without an LPSO. At room temperature, the yield strength and ultimate tensile strength of the three-phase Mg{sub 97}Zn{sub 1}Y{sub 1}La{sub 1} and Mg{sub 97}Zn{sub 1}Y{sub 1}Ce{sub 1} alloys were 381–384 MPa and 427–429 MPa, respectively, and yield strengths greater than 280 MPa were observed at the elevated temperature of 523 K.

Measurements of instant-release source terms for 137Cs, 90Sr, 99Tc, 129I and 14C in used CANDU fuels

International Nuclear Information System (INIS)

Stroes-Gascoyne, S.

1996-01-01

Combined gap and grain-boundary inventories of 137 Cs, 129 I, 90 Sr, 99 Tc and 14 C were measured in 15 used CANDU fuel elements by leaching crushed fuel samples. A good correlation between the combined gap and grain-boundary inventories of 137 Cs and 129 I was found, suggesting that these fission products exhibit similar behavior in CANDU fuel. The expected correlation between combined gap and grain-boundary inventories of 137 Cs and 129 I with calculated fission-gas release to the gap and grain boundaries could only be confirmed for lower power fuels ( 90 Sr were higher than expected and showed no correlation with calculated fission-gas release. No values for the combined gap and grain-boundary inventories of 99 Tc were obtained because 99 Tc in used fuel samples is very insoluble and appears to require oxidation prior to dissolution. Combined gap and grain-boundary inventories of 14 C appeared to be independent of fuel power or burnup. (orig.)

Microfracture behaviour of extruded Mg–Zn–Y alloys containing long-period stacking ordered structure at room and elevated temperatures

International Nuclear Information System (INIS)

Mine, Yoji; Yoshimura, Hajime; Matsuda, Mitsuhiro; Takashima, Kazuki; Kawamura, Yoshihito

2013-01-01

We studied the fracture behaviour of extruded Mg–Zn–Y alloys at room temperature (RT) and at 523 K using microfracture testing. An Mg 97 Zn 1 Y 2 alloy was used to obtain two-phase specimens consisting of α-Mg and long-period stacking ordered (LPSO) structure phases, and an Mg 88 Zn 5 Y 7 alloy was used to obtain specimens consisting of an LPSO phase. The microfracture testing of the two-phase specimen revealed that the fracture behaviour changed from brittle to ductile as the testing temperature increased. By contrast, the LPSO-phase specimen remained brittle even at the elevated temperature and the intrinsic fracture toughness values obtained at both testing temperatures were nearly identical. Ex situ transmission electron microscopy of the two-phase specimen showed that mechanical twinning in the α-Mg phase did not occur at the elevated temperature, although it was activated at RT. This suggests that the plastic deformation mode in the α-Mg phase plays a crucial part in the enhanced crack growth resistance of the two-phase alloy at the elevated temperature

Effect of alloying element on mechanical and oxidation properties of Ni-Cr-Mo-Co alloys at 950 °C

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Jin, E-mail: djink@kaeri.re.kr; Jung, Su Jin; Mun, Byung Hak; Kim, Sung Woo; Lim, Yun Soo; Kim, Woo Gon; Hwang, Seong Sik; Kim, Hong Pyo

2016-12-01

Graphical abstract: Mo rich carbide was developed leading to significant increase of elongation to rupture and creep rupture time of Ni-Cr-Co-Mo alloy at 950 °C. Al addition improved corrosion resistance caused by enhancement of oxide/matrix interface stability. Abstract: The very-high-temperature reactor (VHTR) is a promising Generation-IV reactor design given its clear advantage regarding the production of massive amounts of hydrogen and in generating highly efficient electricity despite the fact that a material challenge remains at a high temperature of around 950 °C, where hydrogen production is possible under high pressure. In particular, among the many components composing a VHTR, the temperature of the intermediate heat exchanger (IHX) is expected to be the highest, with a coolant environment of up to 950 °C. Therefore, this work focuses on the mechanical and oxidation properties at 950 °C as a function of the alloying elements of Cr, Co, Mo, Al, and Ti constituting nickel-based alloys fabricated in a laboratory. The tensile, creep, and oxidation properties of the alloying elements were analyzed with SEM, TEM-EDS, and by assessing the weight change.

Microstructure and refinement performance of Al-Ti-C master alloy: Effect of excess Ti on the growth and nucleating ability of TiC particles

Science.gov (United States)

Svynarenko, Kateryna; Zhang, Yubo; Jie, Jinchuan; Kutsova, Valentyna; Li, Tingju

2017-09-01

Al-5Ti-0.2C, Al-0.8Ti-0.2C, Al-8Ti-2C, and Al-10Ti master alloys were prepared and used to investigate the influence of excess Ti on the growth of TiC particles and its ability to nucleate Al-grains. The results of a microstructure analysis of TiC-containing alloys and refined CPAl were interrelated to the results of a refinement test. It was found that the presence of excess Ti is essential at the stage of master alloy preparation, as it facilitates the growth and uniform distribution of TiC within the structure. In Al-5Ti-0.2C alloy containing excess Ti, carbide particles grow faster and to a higher extent (from 0.29 μm to 0.44 μm) compared to Al-0.8Ti-0.2C alloy produced without excess Ti (from 0.29 μm to 0.32 μm). The results support the "Ti-transition zone theory" as the mechanism of grain refinement by TiC-containing master alloys. The refinement performance of Al-5Ti-0.2C is superior compared to the one achieved by adding Al-8Ti-2C and Al-10Ti master alloys in corresponding concentrations. For the TiC particles to become favourable nucleating sites, they must undergo certain interaction with excess Ti at the stage of master alloy preparation.

Development and selection of a matrix alloy for 85Kr encapsulation

International Nuclear Information System (INIS)

Knoll, R.W.; McClanahan, E.D.; Tingey, G.L.; McDonald, E.L.

1986-07-01

Pacific Northwest Laboratory has developed and demonstrated a pilot-scale process for stable, long-term storage of radioactive 85 Kr gas from spent nuclear fuel. The process entraps the Kr into a solid metal matrix that can be safely stored at ambient pressure. For this matrix numerous alloys were first screened; those that best satisfied the selection criteria were Cu-Y, Ni-Y, and Ni-La. Of these, Cu-Y alloys containing approximately 20 at.% Y were recommended for use in the pilot-scale system. Reasons for this decision, based on the development work described in Section 5, are summarized here. Thick Cu-Y-Kr deposits (greater than or equal to1 mm) exhibit much better thermal and mechanical stability than do those of Ni-La-Kr and are at least as stable as Ni-Y-Kr deposits. Cu-Y-Kr coatings are very compatible with the sputtering process. They adhere well to the substrate, do not spall significantly during deposition, and can be deposited at higher rates than the Ni-base alloys. This faster deposition helps compensate, in terms of process efficiency, for the lower Kr capacity of Cu-Y-Kr alloys. Another advantage of Cu-Y over Ni-base alloys is the higher vapor pressure of Cu compared to Ni. This reduces the unwanted buildup of Cu on the hot anode surface, whereas deposition of Ni is a problem with Ni-Y, for example. Cu-Y-Kr deposits containing 17 to 20 at. % Y and 6 to 8 at. % Kr compared favorably to Ni 80 La 10 Kr 10 in terms of long-term Kr retention characteristics. The measurements of Cu-Y-Kr by differential scanning calorimetry also indicated stable retention of Kr because rapid release did not occur below approx.650 0 C. Finally, Cu-Y alloys are satisfactory in terms of materials costs and producibility of the sputtering target. 13 refs., 9 figs., 4 tabs

E centers in ternary Si1−x−yGexSny random alloys

KAUST Repository

Chroneos, Alexander; Bracht, H.; Grimes, R. W.; Jiang, C.; Schwingenschlö gl, Udo

2009-01-01

Density functional theory calculations are used to study the association of arsenic (As) atoms to lattice vacancies and the formation of As-vacancy pairs, known as E centers, in the random Si0.375Ge0.5Sn0.125 alloy. The local environments are described by 32-atom special quasirandom structures that represent random Si1−x−yGexSny alloys. It is predicted that the nearest-neighbor environment will exert a strong influence on the stability of E centers in ternary Si0.375Ge0.5Sn0.125.

E centers in ternary Si1−x−yGexSny random alloys

KAUST Repository

Chroneos, Alexander

2009-09-14

Density functional theory calculations are used to study the association of arsenic (As) atoms to lattice vacancies and the formation of As-vacancy pairs, known as E centers, in the random Si0.375Ge0.5Sn0.125 alloy. The local environments are described by 32-atom special quasirandom structures that represent random Si1−x−yGexSny alloys. It is predicted that the nearest-neighbor environment will exert a strong influence on the stability of E centers in ternary Si0.375Ge0.5Sn0.125.

Effects of Enrichment and Litter Parity on Reproductive Performance and Behavior in BALB/c and 129/Sv Mice.

Science.gov (United States)

Whitaker, Julia W; Moy, Sheryl S; Pritchett-Corning, Kathleen R; Fletcher, Craig A

2016-01-01

We examined the effect of adding species-appropriate environmental enrichment items to breeding cages of BALB/cAnNCrl and 129S2/SvPasCrl mice. The 3 enrichment conditions were: 1) cotton nesting material; 2) nesting material plus a paper shelter and rolled paper bedding; and 3) an igloo dome with an exercise wheel in addition to the shelter-group enrichments. We measured litter size, litter survival to weaning age, average pup weight at 21 d, and the interlitter interval to evaluate reproductive performance. A random subset of the first- or second-litter offspring from each enrichment condition and strain was assessed in multiple behavioral tests. Enrichment significantly affected anxiety-like behavior and sociability, with the direction of change dependent on strain and sex. Litter parity had greater effects on some reproductive parameters than did the enrichment condition, and this effect was not solely due to a difference between the first compared with subsequent litters. The significant effects of litter parity on the number of pups born and weaned, female pup weight, and interlitter interval were dependent on the enrichment condition in BALB/c but not 129/Sv mice. Offspring from the first or second litter were included in a generational component to investigate whether enrichment effects on reproduction persist in adult offspring after transfer to a different facility for breeding. Natal cage enrichment had no effect on any reproductive parameter in the transferred mice. Overall, additional enrichment beyond nesting material had a beneficial effect on the interlitter interval in BALB/c mice and on the number of pups weaned in 129/Sv mice.

Synthesis of Y2O3 particle enhanced Ni/TiC composite on TC4 Ti alloy by laser cladding%TC4钛合金表面激光熔覆法制备Y2O3颗粒增强Ni/TiC复合涂层

Institute of Scientific and Technical Information of China (English)

张可敏; 邹建新; 李军; 于治水; 王慧萍

2012-01-01

A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer were investigated.The composite layer has graded microstructures and compositions,due to the fast melting followed by rapid solidification and cooling during laser cladding.The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified.The size of TiC dendrites decreases with increasing depth.Y2O3 fine particles distribute in the whole clad layer.The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380,which is 4 times higher than the initial hardness.The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.%采用激光熔覆法在TC4钛合金表面原位制备Y2O3颗粒增强Ni/TiC复合涂层,研究涂层的相组成、微结构、成分分布及性能.结果表明,复合涂层内的微结构和成分在深度方向具有分层现象,这主要是由激光熔覆过程的快速熔凝和冷却过程所致.在激光熔覆过程中,TiC粉末完全熔化并在凝固过程中析出为细小枝晶,这些TiC枝晶的尺寸随着深度的增加而减小,而Y2O3颗粒则分布在整个重熔层中.Y2O3颗粒增强Ni/TiC复合涂层具有较均匀的硬度,其最高值约为HV1380,比基体高4倍以上.由于复合涂层具有高的硬度,钛合金经过激光熔覆后其耐磨性得到大幅度提高.

Iodine-129 and Caesium-137 in Chernobyl contaminated soil and their chemical fractionation

DEFF Research Database (Denmark)

Hou, Xiaolin; Fogh, C.L.; Kucera, J.

2003-01-01

Soil samples from areas in Belarus, Russia and Sweden contaminated by the Chernobyl accident were analysed for I-129 by radiochemical neutron activation analysis, as well as for Cs-137 by gamma-spectrometry. The atomic ratio of I-129/(CS)-C-137 in the upper layer of the examined soil cores ranged...... from 0.10 to 0.30, with an average of 0.18, and no correlation between I-129/Cs-137 ratio and the distance from Chernobyl reactor to sampling location was observed. It seems feasible to use the I-129/Cs-137 ratio to reconstruct the deposition pattern of I-131 in these areas. The association of I-129...... and (CS)-C-137 in the Chernobyl soil and Irish Sea sediment was investigated by a sequential extraction method. Similar speciation of I-129 in the Chernobyl soil and Irish Sea sediment was found. Approximately 70% of I-129 is bound to oxides and organic matter, and 10-20% is in the readily available phase...

Localized corrosion of molybdenum-bearing nickel alloys in chloride solutions

International Nuclear Information System (INIS)

Postlethwaite, J.; Scoular, R.J.; Dobbin, M.H.

1988-01-01

Electrochemical and immersion tests have been applied to a study of the localized corrosion resistance of two molybdenum-bearing nickel alloys. Alloys C-276 and 6y25, in neutral chloride solutions in the temperature range of 25 to 200 C as part of the container materials evaluation screening tests for the Canadian Nuclear Fuel Waste Management Program. Cyclic polarization studies show that the passivation breakdown potentials move rapidly to more active values with increasing temperatures, indicating a reduced resistance to localized corrosion. The results of immersion tests show that both alloys do suffer crevice corrosion in neutral aerated sodium chloride solutions at elevated temperatures, but that in both cases there is a limiting temperature > 100C, below which, the alloys are not attacked, regardless of the chloride concentration

Isothermal equilibrium pressures of Y-Th alloy-H2 system

International Nuclear Information System (INIS)

Tanase, M.; Fisher, P.W.

1985-01-01

Isothermal equilibrium pressures of the Y 4 Th (3:2 by weight) alloy-H 2 system were measured as a function of atomic composition [H]/[Y + Th] in the temperature range 580-1160 K. The isotherms have two plateaux in the pressure range 10 -2 -10 3 Pa. The first plateau region is attributed to the formation of YH 2 , and the equilibrium pressure P in pascals was found to be log P = 12.36 - 11300/T where T is in kelvins. The second plateau is attributed to the formation of ThH 2 , and the equilibrium pressure was found to be log P = 10.66 - 6891/T. In low atomic composition region the system obeys Sieverts' law. (Auth.)

The improvement of the superconducting Y-Ba-Cu-O magnet characteristics through shape recovery strain of Fe-Mn-Si alloys

International Nuclear Information System (INIS)

Shimpo, Y.; Seki, H.; Wongsatanawarid, A.; Taniguchi, S.; Maruyama, T.; Kurita, T.; Murakami, M.

2010-01-01

Since bulk Y-Ba-Cu-O superconductors are brittle ceramics, reinforcement of mechanical properties is important for practical applications. It has been reported that bulk Y-Ba-Cu-O can be reinforced with Al or Fe based alloy ring, in that compression force acts on bulk Y-Ba-Cu-O due to a difference in thermal expansion coefficients. However, the shrinkage of the metal ring was not so large, and therefore careful adjustment of the circumference of the bulk and the metal rings was necessary. In this study, we employed Fe-Mn-Si shape memory alloy rings to reinforce bulk Y-Ba-Cu-O. The advantage of the shape memory alloy is that the shrinkage can take place on heating, and furthermore, the alloy shrinks and compresses the bulk body on cooling. Bulk Y-Ba-Cu-O superconductor 22.8 mm in diameter was inserted in a Fe-Mn-Si ring 23.0 mm in inner diameter at room temperature. Beforehand, the Fe-Mn-Si ring was expanded by 12% strain at room temperature. Then the composite was heated to 673 K. At room temperature, the Fe-Mn-Si ring firmly gripped the bulk superconductor. We then measured trapped fields before and after the ring reinforcement, and found that the trapped field was improved through the treatment.

Magnetic properties of amorphous alloys of Fe with La, Lu, Y, and Zr

International Nuclear Information System (INIS)

Heiman, N.; Kazama, N.

1979-01-01

In order to study the systematics of the Fe-Fe exchange in amorphous rare-earth--Fe alloys, without the complications associated with the magnetic characteristics of the rare-earth elements, amorphous films of Fe alloyed with La, Lu, Y, and Zr have been prepared with a wide range of Fe concentrations. Magnetization and Moessbauer-effect measurements were made. The magnetic properties of the alloys depended critically on the choice of rare earth (or rare-earth-like element). YFe and LuFe alloys were found to have spin-glass characteristics while LaFe and ZrFe alloys were found to be ferromagnetic, but with evidence that exchange fluctuations were nearly as large as the average exchange. Thus the nature of the Fe-Fe exchange interaction depends critically upon the species of the rare earth. The most important parameter in determining the magnetic behavior of these alloys appears to be the size of the rare-earth atom, with large rare-earth atoms resulting in a smaller ratio of exchange fluctuations to exchange. The same dependence of the magnetic properties upon rare-earth size appears to be important in the case of magnetic-rare-earth atoms; however, the effect of rare-earth--Fe exchange also becomes important and these effects are discussed

Influence of nitrogen on the synthesis and nucleation ability of TiC{sub x} in Al–Ti–C master alloy

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ping; Nie, Jinfeng; Gao, Tong; Wang, Tao; Liu, Xiangfa, E-mail: xfliu@sdu.edu.cn

2014-07-15

Highlights: • A group of Al–Ti–C master alloy has been prepared in different concentration of N{sub 2}. • It is found that N atoms can dope into TiC{sub x} at a certain concentration of N{sub 2}. • The effect of N element on the nucleation ability of TiC{sub x} on α-Al is investigated. • The excellent refining performance of the doped TiC{sub x} does not fade within 60 min. - Abstract: In this study, a group of Al–Ti–C master alloy has been prepared in an atmosphere with different concentration of N{sub 2}. The master alloys are analyzed by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). It is discovered that N atoms can be doped into TiC{sub x} at a certain concentration of N{sub 2} while it will form AlN if the concentration is higher. Adding Al–Ti–C master alloy with N doped TiC{sub x} particles in molten aluminum, the average grain size of α-Al can be reduced from 3320 μm to 189 μm and the efficiency does not fade within 60 min. It is supposed that the grain refinement efficiency and stability of TiC{sub x} is improved obviously after N doping. This master alloy exhibits potential to promote the application of grain refiner in industries.

Tensile properties of vanadium alloys irradiated at 200{degrees}C in the HFIR

Energy Technology Data Exchange (ETDEWEB)

Chung, H.M.; Nowicki, L.; Smith, D.L. [Argonne National Lab., IL (United States)

1997-08-01

Vanadium alloys were irradiated in a helium environment to {approx}10 dpa at {approx}200{degrees}C in the High Flux Isotope Reactor (HFIR). This report presents results of postirradiation tests of tensile properties of laboratory heats of V-(1-18)Ti, V-4Cr-4Ti, V-8Cr-6Ti, V-9Cr-5Ti, V-3Ti-1Si, and V-3Ti-0.1C alloys. Because of significant loss of work-hardening capability, all alloys except V-18Ti exhibited a very low uniform plastic strain <1%. For V-Ti. The mechanism of the loss of work-hardening capability in the other alloys is not understood.

Mechanism study of c.f.c Fe-Ni-Cr alloy corrosion in supercritical water

International Nuclear Information System (INIS)

Payet, M.

2011-01-01

Supercritical water can be use as a high pressure coolant in order to improve the thermodynamic efficiency of power plants. For nuclear concept, lifetime is an important safety parameter for materials. Thus materials selection criteria concern high temperature yield stress, creep resistance, resistance to irradiation embrittlement and also to both uniform corrosion and stress corrosion cracking.This study aims for supplying a new insight on uniform corrosion mechanism of Fe-Ni-Cr f.c.c. alloys in deaerated supercritical water at 600 C and 25 MPa. Corrosion tests were performed on 316L and 690 alloys as sample autoclaves taking into account the effect of surface finishes. Morphologies, compositions and crystallographic structure of the oxides were determined using FEG scanning electron microscopy, glow discharge spectroscopy and X-ray diffraction. If supercritical water is expected to have a gas-like behaviour in the test conditions, the results show a significant dissolution of the alloy species. Thus the corrosion in supercritical water can be considered similar to corrosion in under-critical water assuming the higher temperature and its effect on the solid state diffusion. For alloy 690, the protective oxide layer formed on polished surface consists of a chromia film topped with an iron and nickel mixed chromite or spinel. The double oxide layer formed on 316L steel seems less protective with an outer porous layer of magnetite and an inhomogeneous Cr-rich inner layer. For each alloy, the study of the inner protective scale growth mechanisms by marker or tracer experiments reveals that diffusion in the oxide scale is governed by an anionic process. However, surface finishes impact deeply the growth mechanisms. Comparisons between the results for the steel suggest that there is a competition between the oxidation of iron and chromium in supercritical water. Sufficient available chromium is required in order to form a thin oxide layer. Highly deformed or ultra fine

Ab initio calculations of mechanical properties of bcc W-Re-Os random alloys: effects of transmutation of W.

Science.gov (United States)

Li, Xiaojie; Schönecker, Stephan; Li, Ruihuan; Li, Xiaoqing; Wang, Yuanyuan; Zhao, Jijun; Johansson, Börje; Vitos, Levente

2016-06-03

To examine the effect of neutron transmutation on tungsten as the first wall material of fusion reactors, the elastic properties of W 1-x-y  Re x  Os y (0  ⩽  x, y  ⩽  6%) random alloys in body centered cubic (bcc) structure are investigated systematically using the all-electron exact muffin-tin orbitals (EMTO) method in combination with the coherent-potential approximation (CPA). The calculated lattice constant and elastic properties of pure W are consistent with available experiments. Both Os and Re additions reduce the lattice constant and increase the bulk modulus of W, with Os having the stronger effect. The polycrystalline shear modulus, Young's modulus and the Debye temperature increase (decrease) with the addition of Re (Os). Except for C 11 , the other elastic parameters including C 12 , C 44 , Cauchy pressure, Poisson ratio, B/G, increase as a function of Re and Os concentration. The variations of the latter three parameters and the trend in the ratio of cleavage energy to shear modulus for the most dominant slip system indicate that the ductility of the alloy enhances with increasing Re and Os content. The calculated elastic anisotropy of bcc W slightly increases with the concentration of both alloying elements. The estimated melting temperatures of the W-Re-Os alloy suggest that Re or Os addition will reduce the melting temperature of pure W solid. The classical Labusch-Nabarro model for solid-solution hardening predicts larger strengthening effects in W 1-y  Os y than in W 1-x  Re x . A strong correlation between C' and the fcc-bcc structural energy difference for W 1-x-y  Re x  Os y is revealed demonstrating that canonical band structure dictates the alloying effect on C'. The structural energy difference is exploited to estimate the alloying effect on the ideal tensile strength in the [0 0 1] direction.

Improved hydrogen absorption and desorption kinetics of magnesium-based alloy via addition of yttrium

Science.gov (United States)

Yang, Tai; Li, Qiang; Liu, Ning; Liang, Chunyong; Yin, Fuxing; Zhang, Yanghuan

2018-02-01

Yttrium (Y) is selected to modify the microstructure of magnesium (Mg) to improve the hydrogen storage performance. Thereby, binary alloys with the nominal compositions of Mg24Yx (x = 1-5) are fabricated by inexpensive casting technique. Their microstructure and phase transformation during hydriding and dehydriding process are characterized by using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy analysis. The isothermal hydrogen absorption and desorption kinetics are also measured by a Sievert's-type apparatus at various temperatures. Typical multiphase structures of binary alloy can be clearly observed. All of these alloys can reversibly absorb and desorb large amount of hydrogen at proper temperatures. The addition of Y markedly promotes the hydrogen absorption kinetics. However, it results in a reduction of reversible hydrogen storage capacity. A maximum value of dehydrogenation rate is observed with the increase of Y content. The Mg24Y3 alloy has the optimal desorption kinetic performance, and it can desorb about 5.4 wt% of hydrogen at 380 °C within 12 min. Combining Johnson-Mehl-Avrami kinetic model and Arrhenius equation, the dehydrogenation activation energy of the alloys are evaluated. The Mg24Y3 alloy also has the lowest dehydrogenation activation energy (119 kJ mol-1).

Carburization of austenitic and ferritic alloys in hydrocarbon environments at high temperature

Directory of Open Access Journals (Sweden)

Serna, A.

2003-12-01

Full Text Available The technical and industrial aspects of high temperature corrosion of materials exposed to a variety of aggressive environments have significant importance. These environments include combustion product gases and hydrocarbon gases with low oxygen potentials and high carbon potentials. In the refinery and petrochemical industries, austenitic and ferritic alloys are usually used for tubes in fired furnaces. The temperature range for exposure of austenitic alloys is 800-1100 °C, and for ferritic alloys 500-700 °C, with carbon activities a_c > 1 in many cases. In both applications, the carburization process involves carbon (coke deposition on the inner diameter, carbon absorption at the metal surface, diffusion of carbon inside the alloy, and precipitation and transformation of carbides to a depth increasing with service. The overall kinetics of the internal carburization are approximately parabolic, controlled by carbon diffusion and carbide precipitation. Ferritic alloys exhibit gross but uniform carburization while non-uniform intragranular and grain-boundary carburization is observed in austenitic alloys.

La corrosión a alta temperatura, tal como la carburación de materiales expuestos a una amplia variedad de ambientes agresivos, tiene especial importancia desde el punto de vista técnico e industrial. Estos ambientes incluyen productos de combustión, gases e hidrocarburos con bajo potencial de oxígeno y alto potencial de carbono. En las industrias de refinación y petroquímica, las aleaciones austeníticas y ferríticas se utilizan en tuberías de hornos. El rango de temperatura de exposición para aleaciones austeníticas está entre 800-1.100°C y para aleaciones ferríticas está entre 500-700°C, con actividades de carbono a_c>1 en algunos casos. En tuberías con ambas aleaciones, el proceso de carburación incluye deposición de carbón (coque en el diámetro interno, absorción de carbono en la superficie

Compatibility of technologies with regulations in the waste management of H-3, I-129, C-14, and Kr-85. Part II. Analysis

International Nuclear Information System (INIS)

Trevorrow, L.E.; Kolba, V.M.; Vandegrift, G.F.; Steindler, M.J.

1983-11-01

Waste forms of 3 H, 129 I, 14 C, and 85 Kr separated from fuel reprocessing streams and procedures for managing them were analyzed regarding compliance with regulations. Transportation of these wastes in certain DOT-specification packagings would be permissible, but some of these packagings may not be acceptable in some disposal situations. Transportation of gaseous 85 Kr in a currently certified cylinder is possible, but a fuel reprocessor may wish to ship larger quantities per package. Disposal of tritium using a package designed by a DOE contractor and shallow land burial, in accord with the regulations of 10 CFR 61, seems practicable. Although 10 CFR 61 permits shallow land burial of 129 I, the concentration limit requires distribution in a volume that may seem impractical to commercial fuel reprocessors. The concentration limit of 10 CFR 61 for shallow land burial of 14 C requires distribution in a lesser, although still large, volume. For both 129 I and 14 C, management as high-level waste offers the advantage of smaller volumes. Similar advantages may be offered by greater confinement or non-near surface concepts for disposal. The concrete waste forms developed for these nuclides may not meet technical criteria being formulated for geologic disposal. The lack of accommodation of 85 Kr at disposal facilities makes storage of the gaseous form at the fuel reprocessing plant, followed by dispersal after partial decay, seem attractive. Ocean disposal of 129 I and 14 C by the rules of the International Atomic Energy Agency-London Ocean Dumping Convention offers advantages over shallow land burial: higher allowed concentrations, resulting in smaller volumes and fewer packages. These rules, however, thwart ocean disposal of 85 Kr since gaseous forms are banned, and for solid forms, concentration limits would require distribution of radioactivity in very large volumes. 80 references

Tungsten wire--nickel base alloy composite development. Contractor report, 1 Jun 1974--29 Feb 1976

International Nuclear Information System (INIS)

Brentnall, W.D.; Moracz, D.J.

1976-03-01

Further development and evaluation of refractory wire reinforced nickel-base alloy composites is described. Emphasis was placed on evaluating thermal fatigue resistance as a function of matrix alloy composition, fabrication variables and reinforcement level and distribution. Tests for up to 1,000 cycles were performed, and the best system identified in this current work was 50v/o W/NiCrAlY. Improved resistance to thermal fatigue damage would be anticipated for specimens fabricated via optimized processing schedules. Other properties investigated included 1,093 C (2,000 F) stress rupture strength, impact resistance and static air oxidation. A composite consisting of 30v/o W--Hf--C alloy fibers in a NiCrAlY alloy matrix was shown to have a 100-hour stress rupture strength at 1,093 C (2,000 F) of 365 MN/m 2 (53 ksi) or a specific strength advantage of about 3:1 over typical D.S. eutectics

Residual stress and its effect on the mechanical properties of Y-doped Mg alloy fabricated via back-pressure assisted equal channel angular pressing (ECAP-BP)

Energy Technology Data Exchange (ETDEWEB)

Shen, Jianghua, E-mail: j_shen@live.cn [Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States); School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Gärtnerová, Viera [Laboratory of Nanostructures and Nanomaterials, Institute of Physics of the ASCR, Na Slovance 2, CZ – 182 21, Prague 8 (Czech Republic); Kecskes, Laszlo J. [US Army Research Laboratory, Aberdeen Proving Ground, MD 21005-5069 (United States); Kondoh, Katsuyoshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaragi, Osaka 567-0047 (Japan); Jäger, Aleš, E-mail: jager@fzu.cz [Laboratory of Nanostructures and Nanomaterials, Institute of Physics of the ASCR, Na Slovance 2, CZ – 182 21, Prague 8 (Czech Republic); Wei, Qiuming [Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States)

2016-07-04

In this study, pure magnesium (Mg) and Mg-0.6 wt% yttrium (Y) binary alloy were fabricated via casting followed by room temperature equal channel angular pressing (ECAP) using an applied back pressure (BP). Microstructural examination after ECAP-BP revealed a fine-grained Mg-Y alloy with a high residual stress level, whereas, the pure Mg exhibited a well-recrystallized microstructure with uniform and equiaxed grains, but retaining very little residual stress. The Y atoms were present in the Mg matrix as solid solutes and acted as dislocation and grain boundary blockers, thus suppressing dynamic recovery and/or recrystallization during the ECAP process. The Mg-Y alloy had an average grain size of ~400 nm, approximately one order smaller than that of pure Mg. The combination of high residual stress and ultrafine grains of the Mg-Y alloy gave rise to a significant difference in its mechanical behavior from that of the pure Mg, under both quasi-static and dynamic compressive loading.

Methods of I-129 analysis for environmental monitoring

International Nuclear Information System (INIS)

Nomura, T.; Katagiri, H.; Kitahara, Y.; Fukuda, S.

1980-01-01

Among the radioiodine isotopes discharged from nuclear facilities, I-129 has the longest half-life (1.7 x 10 7 years) and thus environmental monitoring of this nuclide is important. Methods of analysis of low level I-129 in environmental samples such as milk, crops, seaweeds and soils are described. The iodine is separated from the dried or pulverized samples by ignition at 1000 0 C in a quartz combustion apparatus with a stream of oxygen. Stable I-127 is simultaneously determined and the atom ratio of 129 I/ 127 I calculated in order to evaluate the thyroid dose by the specific activity method. Results of an analysis of typical food samples collected near the fuel reprocessing plant of Tokai Works showed no I-129 concentrations higher than the detection limit of the method (10 -2 pCi for 10 g. dry sample). (UK)

Development of process route for the production of Fe-0.12C-9CR-2W-0.35Y2O3 ODS alloy tubing for Indian FBR application

International Nuclear Information System (INIS)

Lakshminarayana, B.; Tonpe, S.; Jha, S.K.; Kapoor, Komal; Dubey, A.K.; Gurunadh, J.; Surender, A.; Deshpande, K.V.K.; Maity, P.K.

2011-01-01

In the wake of Nuclear Renaissance, India is playing key role in generation of clean and green Nuclear Energy. It has entered into its second stage Nuclear Power Program on commercial scale with the commencement of construction of 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam. Nuclear Fuel Complex (NFC), Hyderabad is playing a crucial role in the manufacture of all the critical sub-assemblies in SS (D9) grade materials for this reactor. The SS(D9) material with controlled cold work is having very good void swelling resistance and high temperature properties, which can sustain fluence of 100 dpa. The paper covers the manufacturing process and characterization of the ODS tubes for fuel clad application. Manufacturing of 9 Cr 2W Y 2 O 3 - ODS martensitic steel fuel cladding tube has been taken up in Nuclear Fuel Complex, Hyderabad with mechanical alloying followed by MS canning of mechanically alloyed powder, upsetting and hot extrusion and subsequently thermo mechanical process. Manufacturing technology of ODS steel tube is critical with respect its chemical composition, dimensional tolerances, Y 2 O 3 particle size and its distribution and achievement of mechanical properties with proper combination of cold working and heat treatment. The paper covers the manufacturing process and characterization of the ODS tubes for fuel clad application. Manufacturing process for the production of ODS alloy (9 Cr 2W Y 2 O 3 - ODS) has been optimized for mass scale production at NFC

Structural heredity of TiC and its influences on refinement behaviors of AlTiC master alloy

Institute of Scientific and Technical Information of China (English)

王振卿; 刘相法; 柳延辉; 张均燕; 于丽娜; 边秀房

2003-01-01

Heredity of microstructure in AlTiC master alloy, grain refiners, was analyzed. It is found that, for morphologies and distributions of TiC particles, there are visible heredity which originates from raw materials or processing methods of Al melt, and will ultimately be transferred to the solid state structure through the melt stage, and this phenomenon can cause hereditary influences on refinement: formation of chain-like TiC morphology results in rapid refinement fading behavior; distribution of TiC along grain boundaries greatly reduces refinement efficiency. Controlling of structural heredity through proper selections of raw materials and processing parameters is of great importance in obtaining ideal microstructures and improving refinement behaviors of AlTiC master alloys.

Compressive Creep Behaviour of Extruded Mg Alloys at 150 °C

Science.gov (United States)

Fletcher, M.; Bichler, L.; Sediako, D.; Klassen, R.

Wrought magnesium alloy bars, sections and tubes have been extensively used in the aerospace, electronics and automotive industries, where component weight is of concern. The operating temperature of these components is typically limited to below 100°C, since appreciable creep relaxation of the wrought alloys takes place above this temperature.

Understanding the effect of compositions on electronegativity, atomic radius and thermal stability of Mg-Ni-Y amorphous alloy

Science.gov (United States)

Deshmukh, A. A.; Kuthe, S. A.; Palikundwar, U. A.

2018-05-01

In the present paper, the consequences of variation in compositions on the electronegativity (ΔX), atomic radius difference (δ) and the thermal stability (ΔTx) of Mg-Ni-Y bulk metallic glasses (BMGs) are evaluated. In order to understand the effect of variation in compositions on ΔX, δ and ΔTx, regression analysis is performed on the experimentally available data. A linear correlation between both δ and ΔX with regression coefficient 0.93 is observed. Further, compositional variation is performed with δ and then it is correlated to the ΔTx by deriving subsequent equations. It is observed that concentration of Mg, Ni and Y are directly proportional to the δ with regression coefficients 0.93, 0.93 and 0.50 respectively. The positive slope of Ni and Y stated that ΔTx will increase if it has more contribution from both Ni and Y. On the other hand negative slope stated that composition of Mg should be selected in such a way that it will have more stability with Ni and Y. The results obtained from mathematical calculations are also tested by regression analysis of ΔTx with the compositions of individual elements in the alloy. These results conclude that there is a strong dependence of ΔTx of the alloy on the compositions of the constituting elements in the alloy.

Compressive performance and crack propagation in Al alloy/Ti{sub 2}AlC composites

Energy Technology Data Exchange (ETDEWEB)

Hanaor, D.A.H., E-mail: dorian.hanaor@sydney.edu.au [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Hu, L. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Kan, W.H.; Proust, G. [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Foley, M. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia); Karaman, I.; Radovic, M. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States)

2016-08-30

Composite materials comprising a porous Ti{sub 2}AlC matrix and Al 6061 alloy were fabricated by a current-activated pressure assisted melt infiltration process. Coarse, medium and fine meso-structures were prepared with Al alloy filled pores of differing sizes. Materials were subjected to uniaxial compressive loading up to stresses of 668 MPa, leading to the failure of specimens through crack propagation in both phases. As-fabricated and post-failure specimens were analysed by X-ray microscopy and electron microscopy. Quasi-static mechanical testing results revealed that compressive strength was the highest in the fine structured composite materials. While the coarse structured specimens exhibited a compressive strength of 80% relative to this. Reconstructed micro-scale X-ray tomography data revealed different crack propagation mechanisms. Large planar shear cracks propagated throughout the fine structured materials while the coarser specimens exhibited networks of branching cracks propagating preferentially along Al alloy-Ti{sub 2}AlC phase interfaces and through shrinkage pores in the Al alloy phase. Results suggest that control of porosity, compensation for Al alloy shrinkage and enhancement of the Al alloy-Ti{sub 2}AlC phase interfaces are key considerations in the design of high performance metal/Ti{sub 2}AlC phase composites.

The structural changes of Y2O3 in ferritic ODS alloys during milling

International Nuclear Information System (INIS)

Hilger, I.; Tegel, M.; Gorley, M.J.; Grant, P.S.; Weißgärber, T.; Kieback, B.

2014-01-01

Oxide dispersion strengthened (ODS) ferritic steels are usually fabricated via mechanical alloying and subsequent consolidation via hot extrusion or hot isostatic pressing. During the individual process steps, a complex evolution of the nanoparticle structure is taking place. Powders with different Y 2 O 3 contents were milled and examined by means of X-ray diffraction (XRD) and atom probe tomography (APT). It has been observed that the Y 2 O 3 is fragmented and becomes partially amorphous upon milling due to the grain refinement of Y 2 O 3 during the milling process. There was no compelling evidence for Y 2 O 3 dissociation and dissolution into the steel matrix

Magnesium Cermets and Magnesium-Beryllium Alloys; Cermets au magnesium et au magnesium-beryllium; Metallokeramicheskie magnievye i magnievo-berillievye splavy; Cermets de magnesio y aleaciones de magnesio y berillio

Energy Technology Data Exchange (ETDEWEB)

Ivanov, V. E.; Zelenskij, V. F.; Fajfer, S. I.; Zhdanov, S. M.; Maksimenko, V. I.; Savchenko, V. I. [Fiziko-Tekhnicheskij Institut an USSR, Khar' kov, SSSR (Russian Federation)

1963-11-15

The paper describes some results of work on the development of magnesium-magnesium oxide cermets and of super heat-resistant magnesiumberyllium alloys produced by powder metallurgical methods. The introduction of even a minute quantity of finely dispersed magnesium oxide into magnesium results in a strengthening of the material, the degree of which increases with increased magnesium oxide concentration, although variation of this concentration within the limits of 0.3 to 5 wt.% has a comparatively slight effect on the corresponding variation in the short-term strength over the whole range of temperatures investigated. At 20{sup o}C, in the case of the cermets, {sigma}{sub {beta}} = 28 to 31 kg/mm{sup 2} and {delta} = 3 .5 to 4.5%; at 500{sup o}C {sigma}{sub {beta}} = 2.6 to 3.2 kg/mm{sup 2} and {delta} =30 to 40%. The positive effect of the finely dispersed oxide phase is particularly evident in protracted tests. For magnesium cermets, {sigma} (300)/100 = 2.2 kg/mm{sup 2}. Characteristic of the mixtures is the high thermal stability of the strength properties, linked chiefly with the thermodynamic stability of the strength-giving oxide phase in the metal matrix. The use of powder metallurgical methods has yielded super heat-resistant magnesium-beryllium alloys containing heightened concentrations of beryllium (PMB alloys). In their strength characteristics PMB alloys are close to Mg-MgO cermets, but the magnesium-beryllium alloys have a degree and duration of resistance to high temperature oxidation which exceeds the corresponding qualities of the magnesium alloys at present known. Thus, in air of 580{sup o}C, PMB alloys with 2 to 5% beryllium maintain a high resistance to oxidation for a period of over 12000 to 14000 h. This long-term heat resistance is chiefly a result of the amount of beryllium in the alloy, and increases with increasing beryllium content. PMB alloys are also marked by high resistance to short bursts of overheating. Magnesium cermets and

Alleviation of Fermi level pinning at metal/n-Ge interface with lattice-matched Si x Ge1‑ x ‑ y Sn y ternary alloy interlayer on Ge

Science.gov (United States)

Suzuki, Akihiro; Nakatsuka, Osamu; Sakashita, Mitsuo; Zaima, Shigeaki

2018-06-01

The impact of a silicon germanium tin (Si x Ge1‑ x ‑ y Sn y ) ternary alloy interlayer on the Schottky barrier height (SBH) of metal/Ge contacts with various metal work functions has been investigated. Lattice matching at the Si x Ge1‑ x ‑ y Sn y /Ge heterointerface is a key factor for controlling Fermi level pinning (FLP) at the metal/Ge interface. The Si x Ge1‑ x ‑ y Sn y ternary alloy interlayer having a small lattice mismatch with the Ge substrate can alleviate FLP at the metal/Ge interface significantly. A Si0.11Ge0.86Sn0.03 interlayer increases the slope parameter for the work function dependence of the SBH to 0.4. An ohmic behavior with an SBH below 0.15 eV can be obtained with Zr and Al/Si0.11Ge0.86Sn0.03/n-Ge contacts at room temperature.

The effect of the solidification mode on eutectic structure in Fe-C-V alloys

International Nuclear Information System (INIS)

Fras, E.; Guzik, E.

1980-01-01

The aim of the study was to determine such a chemical composition of Fe-C-V alloys which would ensure the formation of perfectly eutectic structures as well as to investigate the eutectic morphology of these alloys when undergoing bulk and directional solidification. Attempts have been done to get in situ composites from Fe-C-V alloys. The adopted testing methods as well as obtained results are described in detail. (H.M.)

Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

Science.gov (United States)

Apparao, K. Ch; Birru, Anil Kumar

2018-01-01

A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

Cat odor exposure induces distinct changes in the exploratory behavior and Wfs1 gene expression in C57Bl/6 and 129Sv mice.

Science.gov (United States)

Raud, Sirli; Sütt, Silva; Plaas, Mario; Luuk, Hendrik; Innos, Jürgen; Philips, Mari-Anne; Kõks, Sulev; Vasar, Eero

2007-10-16

129Sv and C57Bl/6 (Bl6) strains are two most widely used inbred mice strains for generation of transgenic animals. The present study confirms the existence of substantial differences in the behavior of these two mice strains. The exploratory behavior of Bl6 mice in a novel environment was significantly higher compared to 129Sv mice. The exposure of mice to cat odor-induced an anxiety-like state in Bl6, but not in 129Sv mice. The levels of Wfs1 gene expression did not differ in the prefrontal cortex, mesolimbic area and temporal lobe of experimentally naive Bl6 and 129Sv mice. However, after cat odor exposure the expression of Wfs1 gene was significantly lower in the mesolimbic area and temporal lobe of Bl6 mice compared to 129Sv strain. Dynamics of Wfs1 gene expression and exploratory behavior suggest that the down-regulation of Wfs1 gene in Bl6 mice might be related to the increased anxiety. Further studies are needed to test the robustness and possible causal relationship of this finding.

Microstructure of Fe-Cr-C hardfacing alloys with additions of Nb, Ti and, B

International Nuclear Information System (INIS)

Berns, H.; Fischer, A.

1987-01-01

The abrasive wear of machine parts and tools used in the mining, earth moving, and transporting of mineral materials can be lowered by filler wire welding of hardfacing alloys. In this paper, the microstructures of Fe-Cr-C and Fe-Cr-C-Nb/Ti hardfacing alloys and deposits and those of newly developed Fe-Cr-C-B and Fe-Ti-Cr-C-B ones are described. They show up to 85 vol.% of primarily solidified coarse hard phases; i.e., Carbides of MC-, M/sub 7/C/sub 3/-, M/sub 3/C-type and Borides of MB/sub 2/-, M/sub 3/B/sub 2/-, M/sub 2/B-, M/sub 3/B-, M/sub 23/B/sub 6/-type, which are embedded in a hard eutectic. This itself consists of eutectic hard phases and a martensitic or austenitic metal matrix. The newly developed Fe-Cr-C-B alloys reach hardness values of up to 1200 HV and are harder than all purchased ones. The primary solidification of the MB/sub 2/-type phase of titanium requires such high amounts of titanium and boron that these alloys are not practical for manufacture as commercial filler wires

Thermodynamic investigations of the Mn-Ni-C-N quarternary alloys by solid-state galvanic cell technique

International Nuclear Information System (INIS)

Teng Lidong; Aune, Ragnhild; Seetharaman, Seshadri

2005-01-01

In view of the important applications of carbides and nitrides of transition metals in the hard materials industries, the thermodynamic activities of manganese in Mn-Ni-C-N alloys have been studied by solid-state galvanic cell technique with CaF 2 as the solid electrolyte. The phase compositions and microstructure of various alloys have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Nitrogen was introduced into the alloy by equilibrating with N 2 gas. It was established during the experiments that the solubility of nitrogen in the alloys was affected by the carbon content. A (Mn,Ni) 4 (N,C) nitride was formed during the nitriding procedure in the alloys. The electromotive force (EMF) measurements were carried out in the temperature range 940-1127 K in order to determine the activities of Mn in the alloys. The activities of manganese were calculated and compared with those of the corresponding Mn-Ni-C ternary alloys

L10 ordered structures in Al-Cu-(Mg alloys at the early stages of elevated temperature aging

Directory of Open Access Journals (Sweden)

Fuzhong, Xia

2016-09-01

Full Text Available This study concerns the precipitation structures of Al-3Cu and Al-3Cu-1.78Mg (wt. % alloys at the early stages of elevated temperature aging. The Al-3Cu and Al-3Cu-1.78 Mg alloys were solution treated at 540 °C and 500 °C for 2 h, respectively, and then aged at 190 °C for 2 min. The precipitation structures in aged Al-3Cu-(1.78Mg alloys were characterized by Transmission Electron Microscopy (TEM and High Resolution Transmission Electron Microscopy (HTREM. 001 zone axis Selected area electron diffraction patterns indicate that L10 ordered structures are formed in the two aged alloys. HRTEM experiments reveal the partial dislocations on the interfaces of L10 ordered structures. From comparing experimental results with that in the literature, it is concluded that the L10 ordered structures in aged Al-3Cu alloy consist of Al and Cu atoms, and they are comprised by Al, Cu and Mg atoms together in the aged Al-3Cu-1.78Mg alloy. On the basis of precipitate growing thermodynamics, it is thought the L10 ordered structures act as nuclei for GP zones in Al-Cu-(Mg alloys during aging.En este trabajo se estudian las estructuras de precipitación en Al-3Cu y Al-3Cu-1,78Mg (% en peso en los estados iniciales de envejecimiento a temperatura elevada. Las aleaciones Al-3Cu y Al-3Cu-1.78 Mg fueron sometidas a un tratamiento térmico de solución de 2 h a 540 °C y 500 °C, respectivamente, y posteriormente envejecidas 2 min a 190 °C. Las estructuras de precipitación en Al-3Cu-(1.78Mg envejecido fueron caracterizadas por microscopía electrónica de transmisión (TEM y por microscopía electrónica de transmisión de alta resolución (HTREM. Los diagramas de difracción de electrones de área seleccionada indican que se forman estructuras ordenadas L10 en las dos aleaciones envejecidas. Experimentos de HRTEM revelan la presencia de dislocaciones parciales en las intercaras de las estructuras L10 ordenadas. Comparando estos resultados experimentales con la

Dicty_cDB: [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available VF (Link to library) VFC129 (Link to dictyBase) - - - Contig-U16543-1 VFC129F (Link... to Original site) VFC129F 276 - - - - - - Show VFC129 Library VF (Link to library) Clone ID VFC129 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U16543-1 Original site URL http://dict... vs DNA Score E Sequences producing significant alignments: (bits) Value N M91382 |M91382.1 Dictyostelium di...scoideum thioredoxin (TRX2) mRNA, 5' end. 281 2e-96 3 M91384 |M91384.1 Dictyostelium discoideum thioredoxin

2nd Gen FeCrAl ODS Alloy Development For Accident-Tolerant Fuel Cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Massey, Caleb P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Edmondson, Philip D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-01

Extensive research at ORNL aims at developing advanced low-Cr high strength FeCrAl alloys for accident tolerant fuel cladding. One task focuses on the fabrication of new low Cr oxide dispersion strengthened (ODS) FeCrAl alloys. The first Fe-12Cr-5Al+Y₂O₃ (+ ZrO₂ or TiO₂) ODS alloys exhibited excellent tensile strength up to 800 C and good oxidation resistance in steam up to 1400 C, but very limited plastic deformation at temperature ranging from room to 800 C. To improve alloy ductility, several fabrication parameters were considered. New Fe-10-12Cr-6Al gas-atomized powders containing 0.15 to 0.5wt% Zr were procured and ball milled for 10h, 20h or 40h with Y2O3. The resulting powder was then extruded at temperature ranging from 900 to 1050 C. Decreasing the ball milling time or increasing the extrusion temperature changed the alloy grain size leading to lower strength but enhanced ductility. Small variations of the Cr, Zr, O and N content did not seem to significantly impact the alloy tensile properties, and, overall, the 2nd gen ODS FeCrAl alloys showed significantly better ductility than the 1st gen alloys. Tube fabrication needed for fuel cladding will require cold or warm working associated with softening heat treatments, work was therefore initiated to assess the effect of these fabrications steps on the alloy microstructure and properties. This report has been submitted as fulfillment of milestone M3FT 16OR020202091 titled, Report on 2nd Gen FeCrAl ODS Alloy Development for the Department of Energy Office of Nuclear Energy, Advanced Fuel Campaign of the Fuel Cycle R&D program.

Effect of Al-5Ti-0.62C-0.2Ce Master Alloy on the Microstructure and Tensile Properties of Commercial Pure Al and Hypoeutectic Al-8Si Alloy

Directory of Open Access Journals (Sweden)

Wanwu Ding

2017-06-01

Full Text Available Al-5Ti-0.62C-0.2Ce master alloy was synthesized by a method of thermal explosion reaction in pure molten aluminum and used to modify commercial pure Al and hypoeutectic Al-8Si alloy. The microstructure and tensile properties of commercial pure Al and hypoeutectic Al-8Si alloy with different additions of Al-5Ti-0.62C-0.2Ce master alloy were investigated. The results show that the Al-5Ti-0.62C-0.2Ce alloy was composed of α-Al, granular TiC, lump-like TiAl3 and block-like Ti2Al20Ce. Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min can significantly refine macro grains of commercial pure Al into tiny equiaxed grains. The Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 30 min still has a good refinement effect. The tensile strength and elongation of commercial pure Al modified by the Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min increased by roughly 19.26% and 61.83%, respectively. Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min can significantly refine both α-Al grains and eutectic Si of hypoeutectic Al-8Si alloy. The dendritic α-Al grains were significantly refined to tiny equiaxed grains. The morphology of the eutectic Si crystals was significantly refined from coarse needle-shape or lath-shape to short rod-like or grain-like eutectic Si. The tensile strength and elongation of hypoeutectic Al-8Si alloy modified by the Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min increased by roughly 20.53% and 50%, respectively. The change in mechanical properties corresponds to evolution of the microstructure.

Influence of Heat Treatment and Composition Variations on Microstructure, Hardness, and Wear Resistance of C 18000 Copper Alloy

OpenAIRE

Osorio-Galicia, Ramon; Gomez-Garcia, Carlos; Alcantara, Miguel Angel; Herrera-Vazquez, Andres

2012-01-01

The hardness and wear behavior properties of two C 18000 copper alloys with variations in Ni, Si, and Cr concentrations, both within the range of C18000 chemical analysis standard, were studied after the alloy samples had been prepared by melting and casting in sand molds and then heat-treated in solution using two-stage aging for different heating time periods. The results obtained from sample sets of the aforementioned two alloys, C 0 and C 1 , show that the alloy C 1 , with slightly higher...

Hydrogen permeation properties of Pd-coated V89.8Cr 10Y0.2 alloy membrane using WGS reaction gases

KAUST Repository

Jeon, Sungil

2013-05-01

The influence of co-existing gases on the hydrogen permeation was studied through a Pd-coated V89.8Cr10Y0.2 alloy membrane. Preliminary hydrogen permeation experiments have been confirmed that hydrogen flux was 6.26 ml/min/cm2 for a Pd-coated V 89.8Cr10Y0.2 alloy membrane (thick: 0.5 mm) using pure hydrogen as feed gas. Also, the hydrogen permeation flux decreased with decrease of hydrogen partial pressure at constant pressure when H 2/CO2 and H2/CO2/H2S mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert\\'s law in different feed conditions. It was found from XRD and SEM results after permeation test that the Pd-coated V89.8Cr 10Y0.2 alloy membrane had good stability and durability for various mixture feeding conditions. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Hydrogen permeation properties of Pd-coated V89.8Cr 10Y0.2 alloy membrane using WGS reaction gases

KAUST Repository

Jeon, Sungil; Park, Junghoon

2013-01-01

The influence of co-existing gases on the hydrogen permeation was studied through a Pd-coated V89.8Cr10Y0.2 alloy membrane. Preliminary hydrogen permeation experiments have been confirmed that hydrogen flux was 6.26 ml/min/cm2 for a Pd-coated V 89.8Cr10Y0.2 alloy membrane (thick: 0.5 mm) using pure hydrogen as feed gas. Also, the hydrogen permeation flux decreased with decrease of hydrogen partial pressure at constant pressure when H 2/CO2 and H2/CO2/H2S mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert's law in different feed conditions. It was found from XRD and SEM results after permeation test that the Pd-coated V89.8Cr 10Y0.2 alloy membrane had good stability and durability for various mixture feeding conditions. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Manufacturing and characterization of Ni-free N-containing ODS austenitic alloy

Science.gov (United States)

Mori, A.; Mamiya, H.; Ohnuma, M.; Ilavsky, J.; Ohishi, K.; Woźniak, Jarosław; Olszyna, A.; Watanabe, N.; Suzuki, J.; Kitazawa, H.; Lewandowska, M.

2018-04-01

Ni-free N-containing oxide dispersion strengthened (ODS) austenitic alloys were manufactured by mechanical alloying (MA) followed by spark plasma sintering (SPS). The phase evolutions during milling under a nitrogen atmosphere and after sintering were studied by X-ray diffraction (XRD). Transmission electron microcopy (TEM) and alloy contrast variation analysis (ACV), including small-angle neutron scattering (SANS) and ultra-small-angle X-ray scattering (USAXS), revealed the existence of nanoparticles with a diameter of 3-51 nm for the samples sintered at 950 °C. Sintering at 1000 °C for 5 and 15 min caused slight growth and a significant coarsening of the nanoparticles, up to 70 nm and 128 nm, respectively. The ACV analysis indicated the existence of two populations of Y2O3, ε-martensite and MnO. The dispersive X-ray spectrometry (EDS) confirmed two kinds of nanoparticles, Y2O3 and MnO. The material was characterized by superior micro-hardness, of above 500 HV0.1.

Mechanical alloying of the FeNi-Ag system

International Nuclear Information System (INIS)

Gonzalez, G.; Ibarra, D.; Ochoa, J.; Villalba, R.; Sagarzazu, A.

2007-01-01

The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular material with small magnetic grains embedded in a non-magnetic metal matrix. Under equilibrium conditions: Fe-Ag and Ni-Ag are immiscible and Fe-Ni shows complete solubility. These materials are particularly important for magnetoresistivity properties. The properties of these alloys are closely related to their microstructure; therefore, a detailed study of the transformations occurring during milling was undertaken using pre-alloyed Fe x Ni 100-x (x = 30, 50 and 70) further milled with different Ag content to give the following alloys compositions (Fe x -Ni 100-x ) 100-y Ag y (y = 5, 20, 60). Consolidation of the mechanically alloyed powders by sintering at 950 o C was performed. Morphological and structural characterization of the sintered powders was carried out by scanning and transmission electron microscopy and X-ray diffraction. Fe 30 Ni 70 and Fe 50 Ni 50 formed ordered FeNi 3 compound. Fe 70 Ni 30 showed the formation of a mixture of γ-(Fe,Ni) and α-Fe(Ni) solid solutions. The mixture of these systems with Ag showed the metal solid solutions surrounded by Ag islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the γ-(Fe,Ni). High Ag content (60%) shows formation of islands of FeNi surrounded by Ag. Sintering is always improved with the Ag content

Thermal stability of the grain structure in the W-2V and W-2V-0.5Y2O3 alloys produced by hot isostatic pressing

International Nuclear Information System (INIS)

Martínez, J.; Savoini, B.; Monge, M.A.; Muñoz, A.; Armstrong, D.E.J.; Pareja, R.

2013-01-01

Highlights: • W-2V and ODS W-2V-0.5Y 2 O 3 alloys have been produced following a powder metallurgy route. • Grain microstructure and microhardness have been studied after isothermal treatments in vacuum. • Both alloys exhibit a duplex grain size population: a submicron-sized grain and a coarse grained one. • The Y 2 O 3 addition inhibits growth of the coarse grains for T 2 O 3 nanoparticles enhance the microhardness of W-2V-0.5Y 2 O 3 . -- Abstract: W-2V and ODS W-2V-0.5Y 2 O 3 alloys have been produced following a powder metallurgy route consisting of mechanical alloying and a subsequent high isostatic pressing HIP at 1573 K. The grain microstructure and microhardness recovery of the alloys have been studied in samples subjected to isothermal treatments in vacuum in temperature range 1073–1973 K. Both alloys exhibit a duplex grain size distribution consisting of a submicron-sized grain and a coarse-grained population. It has been found that the Y 2 O 3 addition inhibits growth of the coarse grains at T 2 O 3 , respectively, was observed at T ≥ 1573 K. It resulted that the rate constant for grain growth is 30 times higher in W-2V-0.5Y 2 O 3 than in W-2V. The considerable enhancement of the microhardness in the W-2V-0.5Y 2 O 3 appears to be associated to dispersion strengthening

Influence of Y, Gd and Sm on the glass forming ability and thermal crystallization of aluminum based alloy

International Nuclear Information System (INIS)

Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta Filho, W.J.; Danez, G.P.

2010-01-01

Al-based amorphous alloys represent an important family of metals and a great scientific activity has been devoted to determine the main features of both glass forming ability (GFA) and crystallization behavior in order to have a comprehensive framework aimed at potential technological applications. Nowadays, it is well known that the best Al-based amorphous alloys are formed in ternary systems such as Al- RE-TM, where RE is a rare earth and TM a transition metal. This paper presents results of research in Al 85 Ni 10 RE 5 alloys (RE = Y, Gd and Sm). Amorphous ribbons were processed by melt-spinning under the same conditions and subsequently characterized by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results show appreciable micro structural differences as function of the rare earth, thus crystal is obtained for Y, nano-glassy for Gd and, fully amorphous structure for Sm. (author)

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

CSIR Research Space (South Africa)

Mabhali, Luyolo AB

2010-11-01

Full Text Available Laser alloying of aluminium AA1200 was performed with a 4.4kW Rofin Sinar Nd:YAG laser to improve the surface hardness. Alloying was carried out by depositing Ni, Ti and SiC powders of different weight ratios on the aluminium substrate. The aim...

Effects of grain size on high temperature creep of fine grained, solution and dispersion hardened V-1.6Y-8W-0.8TiC

Energy Technology Data Exchange (ETDEWEB)

Furuno, T. [Ehime Univerisity, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Kurishita, H., E-mail: kurishi@imr.tohoku.ac.jp [International Research Center for Nuclear Materials Science, Institute for Materials Research (IMR), Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nagasaka, T.; Nishimura, A.; Muroga, T. [Fusion Engineering Research Center, National Institute for Fusion Science (NIFS), Oroshi-cho 322-6, Tok, Gifu 292 (Japan); Sakamoto, T.; Kobayashi, S.; Nakai, K. [Department of Materials Science and Biotechnology, Ehime Univerisity, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Matsuo, S.; Arakawa, H. [International Research Center for Nuclear Materials Science, Institute for Materials Research (IMR), Tohoku University, Oarai, Ibaraki 311-1313 (Japan)

2011-10-01

Creep resistance is the major concern of vanadium and its alloys for fusion reactor structural applications. In order to elucidate the effects of grain size on the creep behavior of solution and dispersion strengthened vanadium alloys, V-1.6Y-8W-0.8TiC specimens with fine grain sizes from 0.58 to 1.45 {mu}m were prepared by mechanical alloying and HIP without any plastic working and tested at 1073 K and 250 MPa in vacuum. It is shown that the creep resistance of V-1.6Y-8W-0.8TiC depends strongly on grain size and increases with increasing grain size: The creep life for the grain size of 1.45 {mu}m is almost one order longer than that of 0.58 {mu}m, and about two orders longer than that of V-4Cr-4Ti (NIFS-Heat 2) although the grain size of V-4Cr-4Ti is as large as 17.8 {mu}m. The observed creep behavior is discussed in terms of grain size effects on dislocation glide and grain boundary sliding.

Study on the early surface films formed on Mg-Y molten alloy in different atmospheres

Directory of Open Access Journals (Sweden)

A.R. Mirak

2015-09-01

Full Text Available In the present study, the non-isothermal early stages of surface oxidation of liquid Mg-1%Y alloy during casting were studied under UPH argon, dry air, and air mixed with protective fluorine-bearing gases. The chemistry and morphology of the surface films were characterized by SEM and EDX analyses. The results indicate a layer of smooth and tightly coherent oxidation film composed of MgO and Y2O3 formed on the molten Mg-Y alloy surface with 40–60 nm thickness under dry air. A dendritic/cellular microstructure is clearly visible with Y-rich second phases gathered in surface of the melt and precipitated along the grain/cell boundaries under all gas conditions. Under fluorine-bearing gas mixtures, the surface film was a mixed oxide and fluoride and more even; a flat and folded morphology can be seen under SF6 with oxide as dominated phase and under 1, 1, 1, 2-tetra-fluoroethane, a smooth and compact surface film uniformly covering the inner surface of the bubble with equal oxide and fluoride thickness, which results in a film without any major defects. MgF2 phase appears to be the key characteristic of a good protective film.

Ferromagnetic alloy material CoFeC with high thermal tolerance in MgO/CoFeC/Pt structure and comparable intrinsic damping factor with CoFeB

Science.gov (United States)

Chen, Shaohai; Zhou, Jing; Lin, Weinan; Yu, Jihang; Guo, Rui; Poh, Francis; Shum, Danny; Chen, Jingsheng

2018-02-01

The thermal tolerance and perpendicular magnetic anisotropy (PMA) of ferromagnetic alloy Co40Fe40C20 in the structure MgO/CoFeC/Pt (or Ta) were investigated and compared with the commonly used CoFeB alloy. It is found that the PMA of CoFeC with {{K}i,CoFeC}=2.21 erg c{{m}-2} , which is 59% higher than that of CoFeB, can be obtained after proper post-annealing treatment. Furthermore, CoFeC alloy provides better thermal tolerance to temperature of 400 °C than CoFeB. The studies on ferromagnetic resonance show that the intrinsic damping constant α in of Co40Fe40C20 alloy is 0.0047, which is similar to the reported value of 0.004 for Co40Fe40B20 alloy. The comprehensive comparisons indicate that CoFeC alloy is a promising candidate for the application of the integration of spin torque transfer magnetic random access memory with complementary metal-oxide semiconductor processes.

Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

Science.gov (United States)

Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

2003-01-01

Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg- 0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300 F for 24 hours. In this study, a two-step aging treatment was developed through a comprehensive 24 full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175 F and 250 F. The second step aging temperatures was

Microhardness of the YbxY1-xInCu4 alloy system: the of electronic structure on hardness

International Nuclear Information System (INIS)

Ocko, M; Sarrao, J L; Stubicar, N; Aviani, I; Simek, Z; Stubicar, M

2003-01-01

We show that the Vickers microhardness, measured on flux grown single crystals of the Yb x Y 1-x InCu 4 alloy system, although sample dependent, exhibits clear concentration dependence; it increases with decreasing x. Such a dependence is not expected because the cubic lattice parameter increases with decreasing x and one expects then a decrease of hardness with decreasing x. Also, such a concentration dependence is in accordance with neither the Mott-Nabarro theory nor other known experimental results. We ascribe the observed dependence to the change of the electronic structure of the Yb x Y 1-x InCu 4 alloy system with x

The effect of quench rate on the microstructure and properties of AF/C-458 and AF/C-489 Al-Li-Cu-X alloys

Energy Technology Data Exchange (ETDEWEB)

Csontos, A.A.; Gable, B.M.; Starke, E.A. Jr. [Virginia Univ., Charlottesville, VA (United States). Dept. of Mater. Sci. and Eng.; Gaber, A.

2000-07-01

The air force recently developed two isotropic Al-Li-Cu-X alloys with 1.8{sup w}/oLiLi and 2.1{sup w}/oLi designated AF/C-458 and AF/C-489, respectively. The objective of this investigation was to determine the effect of quench rate on the microstructure and mechanical properties of the AF/C-458 and AF/C-489 alloys. TEM, SEM, microhardness, and tensile testing were utilized to ascertain these microstructure/property relationships for both alloys in the T4, T6, and T86 tempers as a function of quench rate. Subsequent losses in ductility for both alloys in all tempers with decreasing quench rate were determined to be due to the precipitation of the equilibrium Al{sub 2}CuLi (T{sub 1}) phase along subgrain and grain boundaries which promoted intergranular fracture. Furthermore, yield and tensile strengths increased for both alloys in the T4 temper but decreased in the T6 and T86 tempers with decreasing quench rate. The increased strengths for the T4 condition resulted from the heterogeneous precipitation of coarse T{sub 1} and naturally aged {delta}' phases. The decrease in yield and tensile strengths for the T6 and T86 tempers were also due to the coarse heterogeneous precipitation of T{sub 1} which denuded regions of Cu thereby reducing the number density of fine matrix {theta}{sup ''} (T6) and T{sub 1} (T86). Finally, a comparison of the quench sensitivity for both the AF/C-458 and AF/C-489 alloys indicates that the mechanical properties for both alloys were less quench rate sensitive than other typical Al-Li-Cu-X alloys. (orig.)

Calculation of glass forming ranges in Al-Ni-RE (Ce, La, Y) ternary alloys and their sub-binaries based on Miedema's model

International Nuclear Information System (INIS)

Sun, S.P.; Yi, D.Q.; Liu, H.Q.; Zang, B.; Jiang, Y.

2010-01-01

Research highlights: → A method based on semi-empirical Miedema's and Toop's model for predicting glass forming range of ternary alloy system has been systematically described. → The method is superior to conventional models by considering the effect of the thermodynamic asymmetric component when dealing with a ternary alloy system. → The glass forming ranges of Al-Ni-RE (Al-Ni-Ce, Al-Ni-Y and Al-Ni-La) systems and their sub-binaries have been successfully calculated. → The present calculations using the method are in well agreement with experiments. → This model is especially useful for predicting the glass forming range of ternary alloy system because the calculations do not require experimental data. - Abstract: A method based on the semi-empirical Miedema's and Toop's model for calculating the glass forming range of a ternary alloy system was systematically described. The method is superior to conventional models by considering the effect of the thermodynamic asymmetric component when dealing with a ternary alloy system. Using this method, the glass forming ranges of Al-Ni-RE (Ce, La, Y) systems and their sub-binaries were successfully predicted. The mixing enthalpy and mismatch entropy were calculated, and their effects on the glass forming abilities of Al-Ni-RE (Ce, La, Y) systems were also discussed. The glass forming abilities of Al-Ni-Ce, Al-Ni-La and Al-Ni-Y are found to be close. The calculated glass forming ranges agree with experiments well. Meanwhile, the enthalpy change from amorphous phase to solid solution in the glass forming ranges was calculated, and the results suggest that those alloys close to the Ni-RE sub-binary system have higher glass forming abilities.

Microstructural and morphological evaluation of MCrAlY/YSZ composite produced by mechanical alloying method

International Nuclear Information System (INIS)

Tahari, M.; Shamanian, M.; Salehi, M.

2012-01-01

Highlights: ► The grain size of CoNiCrAlY decreased as milling time increased. Adding YSZ, delayed decrease of grain size of matrix alloy. ► Increase of milling time and YSZ percent resulted in spherical morphology and homogenous distribution of powders. Adding YSZ also delayed cold welding phenomenon. ► At initial stage of milling, CoNiCrAlY powder showed the greatest hardness but with increases milling time powders contained 15% YSZ showed the maximum hardness. - Abstract: This paper investigates CoNiCrAlY/YSZ composite materials produced by mechanical alloying process. Various amounts of YSZ particles (0%, 5%, 10% and 15 wt.%) were mixed with CoNiCrAlY powder and milled for 12, 24 and 36 h. The structural and mechanical evolutions of the mechanically milled powders were executed using X-ray diffractometry, scanning electron microscopy, optical microscopy and micro-hardness test. It was observed that by increasing milling time, the internal lattice strain of γ-phase matrix increased while grain size of this phase decreased. Also, addition of YSZ to CoNiCrAlY decreased the rate of grain size reduction. In comparison with milled CoNiCrAlY powders, CoNiCrAlY/YSZ milled powders exhibited more spherical morphology and narrower particle size range. Moreover, the increase in milling time caused the homogenous distribution of ceramic particles in CoNiCrAlY matrix, while the increase in YSZ percent decreased the homogenous distribution of ceramic particles in CoNiCrAlY matrix. Besides, micro-hardness tests illustrated that the effect of milling on hardness is more significant than that of ceramic particles addition.

Fracture testing and performance of beryllium copper alloy C 17510

International Nuclear Information System (INIS)

Murray, H.A.; Zatz, I.J.

1992-01-01

A series of test programs was undertaken on copper beryllium alloy C 17510 for several variations in material process and chemistry. These variations in C 17510 were primarily optimized for combinations of strength and conductivity. While originally intended for use as cyclically loaded high-field, high-strength conductors in fusion energy research, material testing of C 17510 has indicated that it is an attractive and economical alternative for a host of other structural, mechanical and electrical applications. ASTM tests performed on three variations of C 17510 alloys included both J-integral and plane strain fracture toughness testing (E813, E399) and fatigue crack growth rate tests (E647), as well as verifying tensile, hardness, Charpy, and other well defined mechanical properties. Fracture testing was performed at both room and liquid nitrogen temperatures, which bound the thermal environment anticipated for the fusion components being designed. Fatigue crack propagation stress ratios ranged from nominal zero to minus one at each temperature

Sulfide phase in the Fe-Ti-S and Fe-C-Ti-S alloys

International Nuclear Information System (INIS)

Malinochka, Ya.N.; Balakina, N.A.; Shmelev, Yu.S.

1976-01-01

The nature of the sulfide phases in Fe-Ti-S and Fe-C-Ti-S alloys was studied. The carbide and the sulfide phase were identified the aid of X-ray spectral microanalysis. It was established that for a small content of titanium and sulfur in ternary Fe-Ti-S alloys the solidification of the γ-solution on the boundaries of dendritic branches is accompanied, along with the precipitation of a sulfide rich in iron of the (Fe, Ti) S type where a small quantity of titanium is dissolved, by the formation of a titanium-bearing sulfide eutectic γ + TiS. The amount of the sulfide eutectic increases with the contents of titanium and sulfur until a purely eutectic alloy is formed. Both carbides and sulfides may be formed in the solidification of quaternary alloys Fe-C-Ti-S

Structural and electronic properties of zinc blende B{sub x}Al{sub 1-x}N{sub y}P{sub 1-y} quaternary alloys via first-principle calculations

Energy Technology Data Exchange (ETDEWEB)

Abdiche, A., E-mail: abdiche_a@yahoo.fr [Engineering Physics Laboratory, Tiaret University, 14000 Tiaret (Algeria); Baghdad, R. [Engineering Physics Laboratory, Tiaret University, 14000 Tiaret (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 Mascara (Algeria); Department of Physics and Astronomy, King Saud University, P.O Box 2455, Riyadh 11451 (Saudi Arabia); Riane, R. [Computational Materials Science Laboratory, University Research of Sidi-Bel-Abbes, 22000 Algeria (Algeria); Al-Douri, Y. [Institute of Nono Electronic Engineering, University Malaysia Perlis, 01000 Kangar, Perlis (Malaysia); Guemou, M. [Engineering Physics Laboratory, Tiaret University, 14000 Tiaret (Algeria); Bin-Omran, S. [Department of Physics and Astronomy, King Saud University, P.O Box 2455, Riyadh 11451 (Saudi Arabia)

2012-02-01

The structural and electronic properties of cubic zinc blende BN, BP, AlN and AlP compounds and their B{sub x}Al{sub 1-x}N{sub y}P{sub 1-y} quaternary alloys, have been calculated using the non relativistic full-potential linearized-augmented plane wave FP-LAPW method. The exchange-correlation potential is treated with the local density approximation of Perdew and Wang (LDA-PW) as well as the generalized gradient approximation (GGA) of Perdew-Burke and Ernzerhof (GGA-PBE). The calculated structural properties of BN, BP, AlN and AlP compounds are in good agreement with the available experimental and theoretical data. A nonlinear variation of compositions x and y with the lattice constants, bulk modulus, direct and indirect band gaps is found. The calculated bowing of the fundamental band gaps is in good agreement with the available experimental and theoretical value. To our knowledge this is the first quantitative theoretical investigation on B{sub x}Al{sub 1-x}N{sub y}P{sub 1-y} quaternary alloy and still awaits experimental confirmations.

Monte-Carlo investigation of in-plane electron transport in tensile strained Si and Si{_{1-y}}C{_y} (y {leq 0.03})

Science.gov (United States)

Dollfus, Ph.; Galdin, S.; Hesto, P.

1999-07-01

Electron transport properties in tensile strained Si-based materials are theoretically analyzed using Monte-Carlo calculation. We focus our interest on in-plane transport in Si and Si{1-y}Cy (yleq 0.03), grown respectively on Effect-Transistor application. In comparison with unstrained Si, the tensile strain effect is shown to be very attractive in Si: drift mobilities greater than 3000 cm^2/Vs are obtained at 300 K for a Ge fraction mole of 0.2 in the pseudo-substrate. In the Si{1-y}Cy/Si system, that does not need any pseudo-substrate, the beneficial strain effect on transport is counterbalanced by the alloy scattering whose influence on mobility is studied. If the alloy potential is greater than about 1 eV, the advantage of strain-induced reduction of effective mass is lost in terms of stationary transport performance at 300 K.

Compositional optimization for nanocrystalline hard magnetic MRE–Fe–B–Zr alloys via modifying RE and B contents

Energy Technology Data Exchange (ETDEWEB)

Qian, D.Y.; Hussain, M.; Zheng, Z.G.; Zhong, X.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Gao, X.X. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Z.W., E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

2015-06-15

To reduce the rare earth content and maintain good magnetic properties for NdFeB based alloys, the effects of RE and B contents on the micro-structure and magnetic properties of nanocrystalline MRE{sub 11−y}Fe{sub 79.5}B{sub 8+y}Zr{sub 1.5} (MRE=Nd{sub 0.8}(Dy{sub 0.5}Y{sub 0.5}){sub 0.2}, y=0–3) alloys have been investigated. Increasing B concentration leads to the appearance and increase of soft magnetic Fe{sub 3}B phase and reduced grain size. With decreasing MRE and increasing B concentrations, the coercivity decreased from 1159.8 kA/m for y=0 to 619.0 kA/m for y=3. The saturation magnetization and remanence increased with B content until y=2 then decreases. The B content also has effects on the exchange coupling, microstructure and thermal stability. While comparing MRE{sub 10}Fe{sub 82.5}B{sub 6}Zr{sub 1.5} alloy with MRE{sub 11−y}Fe{sub 79.5}B{sub 8+y}Zr{sub 1.5} (y=1 and 2) alloys, the alloy with 9 at% MRE can achieve similar magnetic properties as that with 10 at% MRE. The magnetic properties with coercivity of 792.2 kA/m, (BH){sub max} of 128 kJ/m{sup 3} and good thermal stability have been obtained for MRE{sub 9}Fe{sub 79.5}B{sub 10}Zr{sub 1.5} alloy. - Highlights: • Nanocomposite NdFeB composition is optimized to reduce RE from 10 to 9 at.%. • Increasing B content benefits microstructure, exchange coupling, thermal stability. • Alloy with 9% RE has H{sub c}=792kA/m, (BH){sub max}=128kJ/m{sup 3} and low temperature coefficients.

Microstructure, mechanical properties, in vitro degradation and cytotoxicity evaluations of Mg-1.5Y-1.2Zn-0.44Zr alloys for biodegradable metallic implants.

Science.gov (United States)

Fan, Jun; Qiu, Xin; Niu, Xiaodong; Tian, Zheng; Sun, Wei; Liu, Xiaojuan; Li, Yangde; Li, Weirong; Meng, Jian

2013-05-01

Mg-1.5Y-1.2Zn-0.44Zr alloys were newly developed as degradable metallic biomaterials. A comprehensive investigation of the microstructure, mechanical properties, in vitro degradation assessments and in vitro cytotoxicity evaluations of the as-cast state, as-heat treated state and as-extruded state alloys was done. The microstructure observations show that the Mg-1.5Y-1.2Zn-0.44Zr alloys are mainly composed of the matrix α-Mg phases and the Mg12ZnY secondary phases (LPS structure). The hot extrusion method significantly refined the grains and eliminated the defects of both as-cast and heat treated alloys and thereby contributed to the better mechanical properties and biodegradation resistance. The values of tensile strength and tensile yield strength of the alloy in the as-extruded condition are about 236 and 178 MPa respectively, with an excellent elongation of 28%. Meanwhile, the value of compressive strength is about 471 MPa and the value of bending strength is about 501 MPa. The superior bending strength further demonstrates the excellent ductility of the hot extruded alloys. The results of immersion tests and electrochemical measurements in the SBF indicate that a protective film precipitated on the alloy's surface with the extension of degradation. The protective film contains Mg(OH)2 and hydroxyapatite (HA) which can reinforce osteoblast activity and promote good biocompatibility. No significant cytotoxicity towards L-929 cells was detected and the immersion extracts of alloy samples could enhance the cell proliferation with time in the cytotoxicity evaluations, implying that the Mg-1.5Y-1.2Zn-0.44Zr alloys have the potential to be used for biomedical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Improvement of the oxidation resistance of Tribaloy T-800 alloy by the additions of yttrium and aluminium

International Nuclear Information System (INIS)

Zhang, Y.-D.; Zhang, C.; Lan, H.; Hou, P.Y.; Yang, Z.-G.

2011-01-01

Research highlights: → The additions of yttrium (Y) reduced the oxidation rate of Tribaloy T-800 alloy. → Y promoted selective oxidation of Cr due to refinement of alloy phase size. → The oxidation rate was further reduced by Y plus Al with a protective Al 2 O 3 scale. → The positive effect of Y and Al being more pronounced at the higher temperature. - Abstract: The microstructures and oxidation behaviour of the modified Tribaloy T-800 alloys by additions of yttrium and yttrium plus aluminium have been studied. At the presence of yttrium alone, the oxidation rate decreased, and the selective oxidation of chromium was promoted, which was related to the refinement of alloy phase size. The addition of yttrium plus aluminium further reduced the oxidation rate. The selective oxidation of chromium and aluminium were both promoted significantly. The benefits were especially pronounced at 1000 o C, with the formation of protective alumina external layer and no internal oxides, which may be detrimental to the alloy mechanical property.

Arc melting and homogenization of ZrC and ZrC + B alloys

Science.gov (United States)

Darolia, R.; Archbold, T. F.

1973-01-01

A description is given of the methods used to arc-melt and to homogenize near-stoichiometric ZrC and ZrC-boron alloys, giving attention to the oxygen contamination problem. The starting material for the carbide preparation was ZrC powder with an average particle size of 4.6 micron. Pellets weighing approximately 3 g each were prepared at room temperature from the powder by the use of an isostatic press operated at 50,000 psi. These pellets were individually melted in an arc furnace containing a static atmosphere of purified argon. A graphite resistance furnace was used for the homogenization process.

Microstructure and properties of an Al-Ti-Cu-Si brazing alloy for SiC-metal joining

Science.gov (United States)

Dai, Chun-duo; Ma, Rui-na; Wang, Wei; Cao, Xiao-ming; Yu, Yan

2017-05-01

An Al-Ti-Cu-Si solid-liquid dual-phase alloy that exhibits good wettability and appropriate interfacial reaction with SiC at 500-600°C was designed for SiC-metal joining. The microstructure, phases, differential thermal curves, and high-temperature wetting behavior of the alloy were analyzed using scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, and the sessile drop method. The experimental results show that the 76.5Al-8.5Ti-5Cu-10Si alloy is mainly composed of Al-Al2Cu and Al-Si hypoeutectic low-melting-point microstructures (493-586°C) and the high-melting-point intermetallic compound AlTiSi (840°C). The contact angle, determined by high-temperature wetting experiments, is approximately 54°. Furthermore, the wetting interface is smooth and contains no obvious defects. Metallurgical bonding at the interface is attributable to the reaction between Al and Si in the alloy and ceramic, respectively. The formation of the brittle Al4C3 phase at the interface is suppressed by the addition of 10wt% Si to the alloy.

Interfacial morphologies and growth modes of F.C.C. metallic crystals from liquid alloys

International Nuclear Information System (INIS)

Camel, Denis

1980-01-01

Equilibrium and growth morphologies of f.c.c. metallic crystals in contact with liquid alloys have been observed in-situ using transmission electron microscopy. These morphologies have been discussed in terms of atomic interfacial structure and growth mechanisms with the help of a statistical thermodynamic model which takes into account the effects of chemical interactions and interfacial adsorption. (author) [fr

Site preference and elastic properties of ternary alloying additions in B2 YAg alloys by first-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Wu Yurong, E-mail: winwyr@126.com [College of Electromechanical Engineering, Hunan University of Science and Technology, Xiantang 411201 (China); Hu Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China); Xu Longshan [Department of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024 (China)

2012-09-15

First-principles calculations were preformed to study the site preference behavior and elastic properties of 3d (Ti-Cu) transition-metal elements in B2 ductility YAg alloy. In YAg, Ti is found to occupy the Y sublattice whereas V, Cr, Co, Fe, Ni and Cu tend to substitute for Ag sublattice. Due to the addition of 3d transition metals, the lattice parameters of YAg is decreased in the order: Valloy, and Fe is the most effective element to improve the ductility of YAg, while Ti, Ni and V alloying elements can reduce the ductility of YAg alloy, especially, V transforms ductile into brittle for YAg alloy. In addition, both V and Ni alloying elements can increase the hardness of YAg alloy, and Y{sub 8}Ag{sub 7}V is harder than Y{sub 8}Ag{sub 7}Ni.

Early stages of the mechanical alloying of TiC-TiN powder mixtures

Energy Technology Data Exchange (ETDEWEB)

Mura, Giovanna [Dipartimento di Ingegneria Elettrica ed Elettronica, Universita degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy); Musu, Elodia [Industrial Telemicroscopy Laboratory, Sardegna Ricerche, Polaris, Technology Park of Sardinia, Edificio 3, Loc. Piscinamanna, 09010 Pula (Italy); Delogu, Francesco, E-mail: francesco.delogu@dimcm.unica.it [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Universita degli Studi di Cagliari, via Marengo 2, I-09123 Cagliari (Italy)

2013-01-15

The present work focuses on the alloying behavior of TiC-TiN powder mixtures submitted to mechanical processing by ball milling. Accurate X-ray diffraction analyses indicate a progressive modification of the unit cell parameters of the TiC and TiN phases, suggesting the formation of TiC- and TiN-rich solid solutions with an increasingly larger content of solutes. Once the discrete character of the mechanical treatment is taken into due account, the smooth change of the unit cell parameters can be explained by a sequence of mutual dissolution stages related to individual collisions. At each collision, the average chemical composition of small amounts of TiC- and TiN-rich phases changes discontinuously. The discontinuous changes can be tentatively ascribed to local mass transport processes activated by the mechanical deformation of powders at collisions. -- Highlights: Black-Right-Pointing-Pointer Mechanically processed TiC-TiN powder mixtures form two solid solutions. Black-Right-Pointing-Pointer An analytical model was developed to describe the mechanical alloying kinetics. Black-Right-Pointing-Pointer The amount of powder alloyed at collision was indirectly estimated. Black-Right-Pointing-Pointer A few nanomoles of material participate in the alloying process at each collision. Black-Right-Pointing-Pointer The chemical composition of the solid solutions was shown to change discontinuously.

Localized corrosion of Alloy C22 nuclear waste canister material under limiting conditions

International Nuclear Information System (INIS)

Lee, S.G.; Solomon, A.A.

2006-01-01

Localized corrosion behavior of Alloy C22 in simulated Yucca Mountain (YM) repository environments was studied at the highest achievable but realistic temperatures under boiling and dripping scenarios. Temperatures measured in concentrated boiling solutions of KCl and NaNO 3 were found to be stable at 140 deg. C, although transient boiling before dryout was observed at temperatures as high as 160 deg. C, as the electrolyte became progressively more concentrated. Experiments that simulated a dripping scenario with simulated J13 well water confirmed the existence of concentrated solutions stable at 142 ± 3 deg. C under controlled drip conditions leading to pit initiation in Alloy C22 after only a few hours. The polarization experiments conducted at 140 deg. C in a solution with 0.5 mol L -1 chloride concentration showed that the critical potential for localized corrosion was 250 mV (versus Ag/AgCl). Potentiostatic tests confirmed that active metal dissolution occurred only in the crevice region at this potential. The crevice corrosion of Alloy C22 required an incubation time to develop a critical crevice solution, and it was triggered by severe local chemistry (enrichment of Cl - and H + ) aided by the high temperature

Shape memory effect in Fe-Mn-Ni-Si-C alloys with low Mn contents

Energy Technology Data Exchange (ETDEWEB)

Min, X.H., E-mail: MIN.Xiaohua@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Sawaguchi, T.; Ogawa, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Maruyama, T. [Awaji Materia Co., Ltd. 2-3-13, Kanda ogawamachi, Chiyoda, Tokyo 101-0052 (Japan); Yin, F.X. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsuzaki, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0047 (Japan)

2011-06-15

Highlights: {yields} A class of new Fe-Mn-Ni-Si-C shape memory alloys with low Mn contents has been designed. {yields} A Mn content for the onset of the {alpha}' martensite is less than 13 mass%, and the {epsilon} martensite still exists in the alloy with a 9 mass% Mn. {yields} The shape recovery strain decreases considerably when the Mn content is reduced from 13 to 11 mass%. {yields} The sudden decrease in the shape recovery strain is mainly caused by the formation of {alpha}' martensite. - Abstract: An attempt was made to develop a new Fe-Mn-Si-based shape memory alloy from a Fe-17Mn-6Si-0.3C (mass%) shape memory alloy, which was previously reported to show a superior shape memory effect without any costly training treatment, by lowering its Mn content. The shape memory effect and the phase transformation behavior were investigated for the as-solution treated Fe-(17-2x)Mn-6Si-0.3C-xNi (x = 0, 1, 2, 3, 4) polycrystalline alloys. The shape recovery strain exceeded 2% in the alloys with x = 0-2, which is sufficient for an industrially applicable shape memory effect; however, it suddenly decreased in the alloys between x = 2 and 3 although the significant shape recovery strain still exceeded 1%. In the alloys with x = 3 and 4, X-ray diffraction analysis and transmission electron microscope observation revealed the existence of {alpha}' martensite, which forms at the intersection of the {epsilon} martensite plates and suppresses the crystallographic reversibility of the {gamma} austenite to {epsilon} martensitic transformation.

Refractory metal superalloys: Design of yttrium aluminum garnet passivating niobium alloys

Science.gov (United States)

Bryan, David

A systems-based approach, integrating computational modeling with experimental techniques to approach engineering problems in a time and cost efficient manner, was employed to design a Nb-based refractory superalloy for use at 1300°C. Ashby-type selection criteria for both thermodynamic and kinetic parameters were employed to identify a suitable protective oxide for Nb alloys. Yttrium aluminum garnet (YAG) was selected as the most promising candidate for its excellent combination of desirable properties. The alloy microstructural concept was based upon the gamma - gamma' nickel-based superalloys in which the multifunctional gamma' phase serves as both a creep strengthening dispersion and a source of reactive elements for oxide passivation. Candidate ternary Pd-Y-Al and Pt-Y-Al compounds were fabricated and characterized by XRD and DTA. Of the intermetallics studied, only PtYAl had a high enough melting point (1580°C) for use in an alloy operating at 1300°C. The alloy matrix design was based upon Wahl's extension of Wagner's criterion for protective oxidation, requiring a reduction of the product N ODO/DAl by 5 orders of magnitude relative to binary Nb-Al. A thermodynamic and kinetic analysis identified elements with large oxygen affinities as the most beneficial for reducing the magnitude of the quantity NOD O. Construction of a combined thermodynamic and mobility database identified increased Al solubility as the best approach for increasing D Al. Utilizing the thermodynamic and mobility databases, obtained from a combination of model alloys, oxidation experiments, and first principles calculations, theoretical designs predicted the large changes in solubility and transport parameters were achievable. Several prototype alloys were then fabricated and evaluated via oxidation tests at both 1300°C and 1100°C. YAG formation was demonstrated as part of multicomponent oxide scales in the alloys that exhibited the greatest reduction in oxidation rates. The oxidation

Direct gap Ge1-ySny alloys: Fabrication and design of mid-IR photodiodes

Science.gov (United States)

Senaratne, C. L.; Wallace, P. M.; Gallagher, J. D.; Sims, P. E.; Kouvetakis, J.; Menéndez, J.

2016-07-01

Chemical vapor deposition methods were developed, using stoichiometric reactions of specialty Ge3H8 and SnD4 hydrides, to fabricate Ge1-ySny photodiodes with very high Sn concentrations in the 12%-16% range. A unique aspect of this approach is the compatible reactivity of the compounds at ultra-low temperatures, allowing efficient control and systematic tuning of the alloy composition beyond the direct gap threshold. This crucial property allows the formation of thick supersaturated layers with device-quality material properties. Diodes with composition up to 14% Sn were initially produced on Ge-buffered Si(100) featuring previously optimized n-Ge/i-Ge1-ySny/p-Ge1-zSnz type structures with a single defected interface. The devices exhibited sizable electroluminescence and good rectifying behavior as evidenced by the low dark currents in the I-V measurements. The formation of working diodes with higher Sn content up to 16% Sn was implemented by using more advanced n-Ge1-xSnx/i-Ge1-ySny/p-Ge1-zSnz architectures incorporating Ge1-xSnx intermediate layers (x ˜ 12% Sn) that served to mitigate the lattice mismatch with the Ge platform. This yielded fully coherent diode interfaces devoid of strain relaxation defects. The electrical measurements in this case revealed a sharp increase in reverse-bias dark currents by almost two orders of magnitude, in spite of the comparable crystallinity of the active layers. This observation is attributed to the enhancement of band-to-band tunneling when all the diode layers consist of direct gap materials and thus has implications for the design of light emitting diodes and lasers operating at desirable mid-IR wavelengths. Possible ways to engineer these diode characteristics and improve carrier confinement involve the incorporation of new barrier materials, in particular, ternary Ge1-x-ySixSny alloys. The possibility of achieving type-I structures using binary and ternary alloy combinations is discussed in detail, taking into account

High-velocity-oxidation performance of metal-chromium-aluminum (MCrAl), cermet, and modified aluminide coatings on IN-100 and type VIA alloys at 1093 C

Science.gov (United States)

Deadmore, D. L.

1974-01-01

Cermet, MCrAl, and modified aluminide types of coatings applied to IN-100 and NASA-TRW-VIA alloy specimens were cyclically oxidation tested in a high velocity (Mach 1) gas flame at 1093 C. Several coating compositions of each type were evaluated for oxidation resistance. The modified aluminide coating, Pt-Al, applied to alloy 6A proved to be the best, providing oxidation protection to approximately 750 hours based on weight change measurements. The second best, a CoCrAlY coating applied to 6A, provided protection to 450 hours. The third best was a cermet + aluminide coating on 6A with a protection time to 385 hours.

Development of technologies for the waste management of I-129, Kr-85, C-14 and tritium in the Fed. Rep. of Germany

International Nuclear Information System (INIS)

Henrich, E.; Ebert, K.

1985-01-01

The main source of I-129, Kr-85, C-14 and tritium in Germany will be a 10-15 GWe LWR fuel reprocessing plant (FRP), expected to be in operation in the mid nineties. Guidelines for release regulations and development efforts are discussed. It has been recommended to limit the annual I-129 release to less than 0.2 curie. The uncontrolled release of Kr-85, C-14 or tritium via the stack resulting from the 15 GWe power will not exceed the limits derived from the German radiation protection ordinary. The development and hot demonstration of a Kr-85 control technology is recommended in view of the anticipated increasing use of nuclear power in the future. Commercial use of Xe and Kr may also contribute to the incentive for recovery. It would be simple to recover 14CO 2 once separated in the course of the I-129 or Kr-85 removal operations. Tritiated waste water once it has been separated in the course of processing, should not be deliberately released. Therefore, tritium control technology is being developed. General concepts and the present status of reference and back-up technologies as well as additional research in view of advanced processes are summarized

Oxidation between 1000 degrees C and 1600 degrees C and limiting criteria for the use of Zr-doped β-NiAl and β/γ alloys

International Nuclear Information System (INIS)

Doychak, J.; Barrett, C.A.; Smialek, J.L.

1989-01-01

This paper reports the isothermal and cyclic oxidation behavior of Zr-doped β-NiAl and β/γ' intermetallic alloys studied over the temperature range 1000 degrees C-1600 degrees C. Isothermal scale growth was governed by γ-Al 2 O 3 growth kinetics. The scale growth rates showed no monotonic trends with alloy aluminum content, although the stoichiometric β-NiAl alloy had the slowest kinetics. Cyclic oxidation at 1200 degrees C for 1000, 1-hr cycles of alloys having less than approximately 40 at %Al was poor due to the formation of martensite and less protective Ni-containing oxides. The cyclic oxidation behavior of Zr-doped stoichiometric β-NiAl was poor beyond 100, 1-hr cycles at 1425 degrees C. Computer modeling of the cyclic oxidation results was performed to arrive at limiting criteria for alloy service life. The limiting criteria were based on alloy aluminum depletion by oxidation that is necessary for less protective Ni-containing oxide formation. The modelling and lifetime criteria were applied to the cyclic oxidation of a Ni-50.2Al-0.04Zr (at%) alloy

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Rincón Soler, A. I. [Universidad Tecnológica de Pereira, Fac. de Ciencias, Depto. de Física (Colombia); Rodríguez Jacobo, R. R., E-mail: rrrodriguez@uao.edu.co [Universidad Autónoma de Occidente, Fac. de Ciencias Básicas, Depto. de Física (Colombia); Medina Barreto, M. H.; Cruz-Muñoz, B. [Universidad Tecnológica de Pereira, Fac. de Ciencias, Depto. de Física (Colombia)

2017-11-15

Fe{sub 96−X}Co{sub X}C{sub 4} (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

International Nuclear Information System (INIS)

Rincón Soler, A. I.; Rodríguez Jacobo, R. R.; Medina Barreto, M. H.; Cruz-Muñoz, B.

2017-01-01

Fe 96−X Co X C 4 (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

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...

Effect of addition of V and C on strain recovery characteristics in Fe-Mn-Si alloy

International Nuclear Information System (INIS)

Lin Chengxin; Wang Guixin; Wu Yandong; Liu Qingsuo; Zhang Jianjun

2006-01-01

Shape recoverable strain, recovery stress and low-temperature stress relaxation characteristics in an Fe-17Mn-5Si-10Cr-4Ni (0.08C) alloy and an Fe-17Mn-2Cr-5Si-2Ni-1V (0.23C) alloy have been studied by means of X-ray diffraction, transmission electron microscopy and measurement of recoverable strain and recovery stress. The amount of stress-induced ε martensite under tensile deformation at room temperature, recoverable strain and recovery stress are increased obviously with addition V and C in Fe-Mn-Si alloy, which is owing to the influence of addition V and C on strengthening austenitic matrix. Addition of V and C in Fe-Mn-Si alloy is evidently effective to reduce the degree of low-temperature stress relaxation, for the dispersed VC particles 50-180 nm in size precipitated during annealing restrain the stress induced martensitic transformation

Precipitate evolution in underaged Al-Mg-Si alloy during thermal cycling between 25 deg. C and 65 deg. C

International Nuclear Information System (INIS)

Uan, J.-Y.; Cho, C.-Y.; Chen, Z.-M.; Lin, J.-K.

2006-01-01

The evolution of metastable precipitates and the aging response in underaged Al-Mg-Si alloy during environmental temperature cycling was investigated using transmission electron microscopy (TEM) and hardness tests. After the alloy underwent thermal cycling between 25 deg. C and 65 deg. C, the hardness tests revealed that hardness decreased slightly, rather than following a concave downward curve, with the cycle times. Needle-shaped G.P. zones transformed during the environmental thermal cycling. The fraction of the zones declined sharply from almost 100% to only approximately 10% after 90 cycles, accompanied by an increase in the fraction of lath-shaped precipitates and the formation of β'' precipitates in the matrix. The precipitate developed with the 25-65 deg. C cycling time as follows: needle-shaped G.P. zones → lath-shaped ppt + β'' ppt + needle-shaped G.P. zones → lath-shaped ppt + β'' ppt + rod-shaped ppt + needle-shaped G.P. zones. Therefore, three or four precipitates coexisted in the underaged alloy following prolonged cycling. The formation of a limited number of β'' precipitates and the presence of a rod-shaped phase in the alloy during environmental temperature cycling reduced the hardness as the cycle time increases

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

Dicty_cDB: SLH678 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available SL (Link to library) SLH678 (Link to dictyBase) - - - Contig-U04159-1 SLH678E (Link... to Original site) - - - - - - SLH678E 373 Show SLH678 Library SL (Link to library) Clone ID SLH678 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U04159-1 Original site URL http://dict... producing significant alignments: (bits) Value N ( AU039970 ) Dictyostelium discoideum slug cDNA, clone SLG...865. 323 e-129 2 ( AU039381 ) Dictyostelium discoideum slug cDNA, clone SLH678. 3

TEM examination of microstructural evolution during processing of 14CrYWTi nanostructured ferritic alloys

International Nuclear Information System (INIS)

Kishimoto, H.; Alinger, M.J.; Odette, G.R.; Yamamoto, T.

2004-01-01

A transmission electron microscopy (TEM) study was carried out on the co-evolution of the coarser-scale microstructural features in mechanically alloyed (MA) powders and hot isostatic press (HIP) consolidated Fe-14Cr-3W-0 and 0.4Ti-0.25Y 2 O 3 nanostructured ferritic alloys (NFAs). The pancake shaped nanoscale grains in the as-MA powders are textured and elongated parallel to the particle surface. Powder annealing results in re-crystallization at 850 deg. C and grain growth at 1150 deg. C. The grains also recrystallize and may grow in the alloys HIPed at 850 deg. C, but appear to retain a polygonized sub-grain structure. The grains are larger and more distinct in the alloys HIPed at 1000 and 1150 deg. C. However, annealing resulted in bi-modal grain size distribution. Finer grains retained a significant dislocation density and populations of small precipitates with crystal structures distinct form the matrix. The grains and precipitates were much larger in alloys without Ti

Inhibited Aluminization of an ODS FeCr Alloy

International Nuclear Information System (INIS)

Vande Put Ep Rouaix, Aurelie; Pint, Bruce A.

2012-01-01

Aluminide coatings are of interest for fusion energy applications both for compatibility with liquid Pb-Li and to form an alumina layer that acts as a tritium permeation barrier. Oxide dispersion strengthened (ODS) ferritic steels are a structural material candidate for commercial reactor concepts expected to operate above 600 C. Aluminizing was conducted in a laboratory scale chemical vapor deposition reactor using accepted conditions for coating Fe- and Ni-base alloys. However, the measured mass gains on the current batch of ODS Fe-14Cr were extremely low compared to other conventional and ODS alloys. After aluminizing at two different Al activities at 900 C and at 1100 C, characterization showed that the ODS Fe-14Cr specimens formed a dense, primarily AlN layer that prevented Al uptake. This alloy batch contained a higher (> 5000 ppma) N content than the other alloys coated and this is the most likely reason for the inhibited aluminization. Other factors such as the high O content, small (∼ 140 nm) grain size and Y-Ti oxide nano-clusters in ODS Fe-14Cr also could have contributed to the observed behavior. Examples of typical aluminide coatings formed on conventional and ODS Fe- and Ni-base alloys are shown for comparison.

Repassivation potential for localized corrosion of Alloys 625 and C22 in simulated repository environments

International Nuclear Information System (INIS)

Cragnolino, G.A.; Dunn, D.S.; Sridhar, N.

1998-01-01

Two corrosion resistant nickel-based alloys, 625 and C22, have been selected by the US Department of Energy as candidate materials for the inner container of high-level radioactive waste packages. The susceptibility of these materials to localized corrosion was evaluated by measuring the repassivation potential as a function of solution chloride concentration and temperature using cyclic potentiodynamic polarization and lead-in-pencil potential step test methods. At intermediate Cl- concentrations, e.g., 0.028--0.4 M, the repassivation potential of alloy 625 is greater than that for alloy 825 and is dependent on the Cl- concentration. However, at higher concentrations, the repassivation potential is slightly less than that for alloy 825 and is weakly dependent on Cl- concentration. The repassivation potentials for alloy C-22 under all test conditions are considerably higher than those of either alloy 625 or 825 and are in the range where oxygen evolution is expected to occur

Hard coatings on magnesium alloys by sputter deposition using a pulsed d.c. bias voltage

Energy Technology Data Exchange (ETDEWEB)

Reiners, G. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany); Griepentrog, M. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany)

1995-12-01

An increasing use of magnesium-based light-metal alloys for various industrial applications was predicted in different technological studies. Companies in different branches have developed machine parts made of magnesium alloys (e.g. cars, car engines, sewing and knitting machines). Hence, this work was started to evaluate the ability of hard coatings obtained by physical vapour deposition (PVD) in combination with coatings obtained by electrochemical deposition to protect magnesium alloys against wear and corrosion. TiN hard coatings were deposited onto magnesium alloys by unbalanced magnetron sputter deposition. A bipolar pulsed d.c. bias voltage was used to limit substrate temperatures to 180 C during deposition without considerable loss of microhardness and adhesion. Adhesion, hardness and load-carrying capacity of TiN coatings deposited directly onto magnesium alloys are compared with the corresponding values of TiN coatings deposited onto substrates which had been coated electroless with an Ni-P alloy interlayer prior to the PVD. (orig.)

Estudios sobre el papel del área tegmental ventral y de las regiones dopaminérgicas rostral lineal y periacueductal del mesencéfalo en la adicción y analgesia opiáceas en ratas

OpenAIRE

Flores Cordero, Juan Antonio

2005-01-01

Falta por incorporar las palabras clave El número medio de cada tipo celular fue de 129,431,3 células grandes de la PAG ventrolateral, 305,843,5 células periacueductales de la PAG y 1441,4210 células pequeñas de la región RLi/PAG ventral. 3. En las neuronas dopamimérgicas grandes de la PAG y pequeñas de la región Rli/PAG ventral (pero no en las periacueductales) se produce una regulación al alza en la expresión de TH tras el tratamiento repetido y subcutáneo con heroína. 4. La infusión del...

J129 in the biocycle

International Nuclear Information System (INIS)

Handl, J.; Kuehn, W.

1980-01-01

A brief survey on the few known data on the radioecological behaviour of 129 J is given. Numerous investigations as to the 129 J-uptake in the thyroid of cattle were carried out in the USA. In Western Europe, practically only in the near surroundings of nuclear-technical plants measurements of 129 J were carried out. In the author's opinion, to clarify the ecological behaviour of 129 J, human thyroids should be examined as well, in special regions the share of 129 J in milk, grass, food, and ground-near air should be determined and tests with especially important iodine compounds from various soils and plants should be carried out concerning this re-emissions. (MG) [de

Passivation kinetics of Mg-Nd-Gd-Zn-Zr (EV31A and Mg-Y-Nd-Gd-Zr (WE43C in NaOH solutions

Directory of Open Access Journals (Sweden)

Jakraphan Ninlachart

2017-09-01

Full Text Available Passivation kinetics of two Mg-RE alloys, such as Mg-Nd-Gd-Zn-Zr (EV31A, and Mg-Y-Nd-Gd-Zr (WE43C were investigated in two different heat treated conditions (solution treated and overaged in 0.01 - 1.0 M NaOH solutions under potentiostatic conditions. Negative reaction order was observed in dilute NaOH which transitioned to positive values as the passivation time increased and in the 1 M NaOH as well. The passive layers showed platelet morphology and the size of the platelets decreased with increase in the NaOH concentration. The hydrogen evolution reaction (HER kinetics was not improved on the passive layer covered surface of the Mg-RE alloys in contrast to the improvements reported on the hydroxide covered pure magnesium. The electrochemical impedance increased with increase in the NaOH concentration in the solution treated condition of both Mg-RE alloys, whereas the overaged EV31A alloy showed a reverse trend. The passive layer of EV31A showed almost 100% higher charge carrier density than the film formed on the WE43C in the overaged condition. A better passivation behavior was observed in the solution treated condition than that in the overaged condition which could be attributed to the uniform distribution of the RE elements in the solution treated specimens. The WE43C alloy revealed better corrosion resistance in the alkaline solution than the EV31A alloy.

Determination method for 129I in soil samples by MIP-MS

International Nuclear Information System (INIS)

Uezu, Yasuhiro; Nakano, Masanao; Fujita, Hiroki; Watanabe, Hitoshi; Maruo, Yoshihiro

2001-01-01

The radioactive iodine-129 ( 129 I) is an important radionuclide for environmental assessment because it has a long half-life and is accumulated in the thyroid gland in humans. A new analytical technique by Microwave Induced Plasma Mass Spectrometer (MIP-MS) was applied to the determination of 129 I in soil samples. In environmental samples, a large amount of matrix elements are present. Therefore, the matrix elements were eliminated by ashing at 1000degC, and iodine isotopes were trapped by an activated charcoal and finally extracted by 10% tetramethylammonium hydroxide (TMAH). The concentration of 129 I in a soil samples were compared between results of neutron activation analysis and MIP-MS method. The results showed an excellent agreement. (author)

Thermal shock behavior of W-0.5 wt% Y_2O_3 alloy prepared via a novel chemical method

International Nuclear Information System (INIS)

Zhao, Mei-Ling; Luo, Lai-Ma; Lin, Jing-Shan; Zan, Xiang; Zhu, Xiao-Yong; Luo, Guang-Nan; Wu, Yu-Cheng

2016-01-01

A wet-chemical method combined with spark plasma sintering was used to prepare W-0.5 wt% Y_2O_3 alloy. The W-0.5 wt% Y_2O_3 precursor was reduced at 800 °C for 4 h under different hydrogen flow rates of 300, 400, 500, 600, and 700 ml/min. The reduced powder was analyzed by X-ray diffraction (XRD), laser particle size analyzer (LPSA), and scanning electron microscopy (SEM). An optimized process for reducing precursor was discussed. After sintering, the specimens were exposed to different laser beam irradiation energies (90, 120, 150, and 180 W) to simulate loads as expected for edge localized modes (ELMs). Top surface and cross-sectional morphology were observed by SEM, and the changes in hardness were evaluated. The changes in microstructural properties (i.e., Y_2O_3-particle distribution, crack propagation direction, depth of thermal shock effect, and grain size of the recrystallization region) after thermal shock were investigated.

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.

The tensile properties of alloys 800H and 617 in the range 20 to 950deg C

International Nuclear Information System (INIS)

Abd El-Azim, M.E.; Ennis, P.J.; Schuster, H.; Nickel, H.

1990-01-01

The tensile properties of Alloy 800H and Alloy 617 in the solution treated condition and after ageing or carburization have been determined for the temperature range 20 to 950deg C. It was found that ageing at 900deg C prior to testing led to an increase in strength and a decrease in ductility at test temperatures up to 700deg C. Above 700deg C, there was no significant difference between the tensile properties of solution treated and aged material. Carburization caused a severe loss of ductility in both alloys at temperatures of 20 to around 800deg C, but the ductility increased sharply at test temperatures above 800deg C, accompanied by a change in the fracture mode from fracture of the carbide particles themselves to void formation and separation at the carbide/matrix interface. The correlation between tensile properties and creep data was investigated in tests carried out at different strain rates. Reasonable agreement was found at 800 to 950deg C for Alloy 617 and at 800 to 900deg C for Alloy 800H. Strain ageing effects were observed in both alloys at some temperatures and strain rates; these effects were serrated flow, negative strain rate sensitivity, peaks in the normalized UTS-temperature curves and plateaus in the elongation-temperature curves. The experimental results were interpreted in the light of two current models for strain ageing, the dislocation-dislocation interaction model and the dislocation-solute interaction model. (orig.) [de

Quasicrystal-reinforced Mg alloys.

Science.gov (United States)

Kyun Kim, Young; Tae Kim, Won; Hyang Kim, Do

2014-04-01

The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg-Zn-Y and Mg-Zn-Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α -Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg-Zn-Y alloys, the co-presence of I and Ca 2 Mg 6 Zn 3 phases by addition of Ca can significantly enhance formability, while in Mg-Zn-Al alloys, the co-presence of the I-phase and Mg 2 Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg-Zn-Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg-Zn-Al-Sn alloys is attributed to the presence of finely distributed Mg 2 Sn and I-phase particles embedded in the α -Mg matrix.

Radiation-induced segregation and void formation in C+ ion-irradiated vanadium-carbon alloys

International Nuclear Information System (INIS)

Takeyama, T.; Ohnuki, S.; Takahashi, H.; Sato, Y.; Mochizuki, S.

1982-01-01

To clarify the effect of interstitial elements on radiation-induced segregation and void formation in V and V-C alloys irradiated by 200 keV C + ions to a dose of 48 dpa at 973 K, the microstructural observation and the measurement of C segregation to the surfaces were carried out by TEM and XPS. Voids, dislocations and precipitates were produced in all of the specimens during irradiation. The addition of C in V led to a reduction of void size and to increase in void number density, consequently the void swelling was suppressed strongly. Radiation-induced segregation of C was observed clearly on and near the irradiated surfaces of V-C alloys and as a result of the enrichment of C atoms, carbides precipitated on the surfaces. It is the first evidence of the radiation-induced segregation of interstitial elements on the surfaces. Also, quasi-carbides were observed on the (210) habit plaints near large voids and dislocations in V. The phenomena show that C atoms, which was insolved and/or implanted, interact strongly with vacancies rather than self-interstitial atoms and migrate with vacancies toward defect sinks, such as surfaces, voids, and dislocations. The segregated zones of C reduced the sink efficiency of the defects, and showed the effect of the suppression on void in V-C alloys. (author)

Effect of precipitates on microstructures and properties of forged Mg-10Gd-2Y-0.5Zn-0.3Zr alloy during ageing process

International Nuclear Information System (INIS)

Han, X.Z.; Xu, W.C.; Shan, D.B.

2011-01-01

Highlights: · The effect of forging process on microstructure evolution and mechanical properties of Magnesium alloy with rare earth was investigated. · The optimal mechanical properties of the alloy with high strength and enough elongation were obtained after forging and ageing process. · The strength improvement of the alloy after forging and ageing process mainly results from the precipitation of 14H-type LPSO phase. · Strengthening mechanism of the alloy is controlled by the precipitation of β' and 14H-type LPSO phases which can inhibit sliding of dislocations and growth of grain boundaries. - Abstract: The precipitate behavior during forging and ageing process of Mg-10Gd-2Y-0.5Zn-0.3Zr alloy has been investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical properties of the alloy after forging and ageing process have been evaluated using Vickers hardness and room-temperature tensile tests. The results show that precipitation of 14H-type long period stacking order (LPSO) phase is the main strengthening phase in the as-forged alloy. The LPSO phase and refinement of grains contribute to the strength improvement of the alloy after forging process. The optimal mechanical properties of the alloy are obtained when it is aged at 200 deg. C for 60 h, which mainly owes to the precipitation of large amounts of β' and 14H-type LPSO phases on the α-Mg matrix. The growth of secondary phases, widening of soft precipitate free zones and coarsening of grains during subsequent ageing process at higher temperature lead to the decrease of mechanical properties of the alloy.

Thermal stability of the grain structure in the W-2V and W-2V-0.5Y{sub 2}O{sub 3} alloys produced by hot isostatic pressing

Energy Technology Data Exchange (ETDEWEB)

Martínez, J.; Savoini, B.; Monge, M.A. [Departamento de Física, Universidad Carlos III de Madrid, 28911-Leganés Madrid (Spain); Muñoz, A., E-mail: angel.munoz@uc3m.es [Departamento de Física, Universidad Carlos III de Madrid, 28911-Leganés Madrid (Spain); Armstrong, D.E.J. [Department of Materials, University of Oxford, Park Road, Oxford OX1 3PH (United Kingdom); Pareja, R. [Departamento de Física, Universidad Carlos III de Madrid, 28911-Leganés Madrid (Spain)

2013-10-15

Highlights: • W-2V and ODS W-2V-0.5Y{sub 2}O{sub 3} alloys have been produced following a powder metallurgy route. • Grain microstructure and microhardness have been studied after isothermal treatments in vacuum. • Both alloys exhibit a duplex grain size population: a submicron-sized grain and a coarse grained one. • The Y{sub 2}O{sub 3} addition inhibits growth of the coarse grains for T < 1973 K. • The Y{sub 2}O{sub 3} nanoparticles enhance the microhardness of W-2V-0.5Y{sub 2}O{sub 3}. -- Abstract: W-2V and ODS W-2V-0.5Y{sub 2}O{sub 3} alloys have been produced following a powder metallurgy route consisting of mechanical alloying and a subsequent high isostatic pressing HIP at 1573 K. The grain microstructure and microhardness recovery of the alloys have been studied in samples subjected to isothermal treatments in vacuum in temperature range 1073–1973 K. Both alloys exhibit a duplex grain size distribution consisting of a submicron-sized grain and a coarse-grained population. It has been found that the Y{sub 2}O{sub 3} addition inhibits growth of the coarse grains at T < 1973 K. Submicron grain growth, with activation enthalpy of 1.9 and 2.49 eV for W-2V and W-2V-0.5Y{sub 2}O{sub 3}, respectively, was observed at T ≥ 1573 K. It resulted that the rate constant for grain growth is 30 times higher in W-2V-0.5Y{sub 2}O{sub 3} than in W-2V. The considerable enhancement of the microhardness in the W-2V-0.5Y{sub 2}O{sub 3} appears to be associated to dispersion strengthening.

Martensitic transformation in Heusler alloys Mn2YIn (Y=Ni, Pd and Pt): Theoretical and experimental investigation

International Nuclear Information System (INIS)

Luo, Hongzhi; Liu, Bohua; Xin, Yuepeng; Jia, Pengzhong; Meng, Fanbin; Liu, Enke; Wang, Wenhong; Wu, Guangheng

2015-01-01

The martensitic transformation and electronic structure of Heusler alloys Mn 2 YIn (Y=Ni, Pd, Pt) have been investigated by both first-principles calculation and experimental investigation. Theoretical calculation reveals that, the energy difference ΔE between the tetragonal martensitic phase and cubic austenitic phase increases with Y varying from Ni to Pt in Mn 2 YIn. Thus a structural transition from cubic to tetragonal is most likely to happen in Heusler alloy Mn 2 PtIn. A single Heusler phase can be obtained in both Mn 2 PtIn and Mn 2 PdIn. A martensitic transformation temperature of 615 K has been identified in Mn 2 PtIn. And in Mn 2 PdIn, the austenitic phase is stable and no martensitic transformation is observed till 5 K. This indicates there may exist a positive relation between ΔE and martensitic transformation temperature. Calculated results show that Mn 2 YIn are all ferrimagnets in both austenitic and martensitic phases. The magnetic properties are mainly determined by the antiparallel aligned Mn spin moments. These findings can help to develop new FSMAs with novel properties. - Highlights: • Positive relation between ΔE and martensitic transformation temperature has been observed. • Heusler alloy Mn 2 PdIn has been synthesized successfully and investigated. • Martensitic transformation in Heusler alloys can be predicted by first -principles calculations

Reactive wetting of Ti-6Al-4V alloy by molten Al 4043 and 6061 alloys at 600-700 C

Energy Technology Data Exchange (ETDEWEB)

Lin, Qiaoli; Li, Fuxiang; Jin, Peng; Yu, Weiyuan [Lanzhou Univ. of Technology (China). State Key Lab. of Advanced Processing and Recycling of Non-ferrous Metal

2017-06-15

Wetting of Ti-6Al-4V alloy by two industrial grade Al alloys (i.e., Al 6061 and 4043 alloys) was studied using the sessile drop method at 600-700 C under high vacuum. Al/Ti-6Al-4V is a typical reactive wetting system with good final wettability accompanied by the formation of precursor film which is actually an extended reaction layer. The formation mechanism for the precursor film is ''subcutaneous infiltration''. The small amount of alloying element Si in the alloys can cause significant segregation at the liquid/solid interface which satisfies the thermodynamic condition. The wetting behavior can be described by the classic reaction product control models, and Ti{sub 7}Al{sub 5}Si{sub 12} decomposition and Al{sub 3}Ti formation correspond to the two spreading stages. The small difference in alloying elements in Al 6061 and 4043 resulted in distinctly different interface structures, formation of precursor film and spreading dynamics, especially for the Si segregation at the interface.

Microstructures and properties of TiN reinforced Co-based composite coatings modified with Y_2O_3 by laser cladding on Ti–6Al–4V alloy

International Nuclear Information System (INIS)

Weng, Fei; Yu, Huijun; Chen, Chuanzhong; Liu, Jianli; Zhao, Longjie

2015-01-01

In this study, TiN reinforced composite coatings were fabricated on Ti–6Al–4V substrate by laser cladding with Co42 self-fluxing alloy, TiN and Y_2O_3 mixed powders. Microstructures and wear resistance of the cladding coatings with and without Y_2O_3 addition were investigated comparatively. Results showed that the coatings were mainly comprised of γ-Co/Ni, TiN, CoTi, CoTi_2, NiTi, TiC, Cr_7C_3, TiB, Ti_5Si_3 and TiC_0_._3N_0_._7 phases. The coatings showed metallurgical bonding free of pores and cracks with the substrate. Compared with the Ti–6Al–4V substrate, the microhardness and wear resistance of the coatings was enhanced by 3–4 times and 9.5–11.9 times, respectively. With 1.0 wt.% Y_2O_3 addition, the microstructure of the coating was refined significantly, and the microhardness and dry sliding wear resistance were enhanced further. The effects of Y_2O_3 were attributed to the residual Y_2O_3 and decomposed Y atoms. - Graphical abstract: The diagram illustration for the action mechanism of Y_2O_3: (a) dissolution of Y_2O_3 and TiN, (b) re-formation of TiN and in situ formation of TiC, (c) growth of TiN, TiC and the distribution of Y atoms. - Highlights: • Coatings showing metallurgical bonding with the substrate were fabricated. • The effect of Y_2O_3 on the refinement of the microstructure is notable. • A kind of Y_2O_3 centered core–shell structure was picked out in the coating. • Microhardness and wear resistance of the coatings was enhanced significantly.

Pressure effect on thermopower of Y1-xGdxCo2 alloy system

International Nuclear Information System (INIS)

Nakama, T.; Takaesu, Y.; Uchima, K.; Yagasaki, K.; Hedo, M.; Uwatoko, Y.; Burkov, A.T.

2007-01-01

Thermopower of Y 1-x Gd x Co 2 pseudobinary compounds has been measured at temperatures from 1.5 to 300K under hydrostatic pressure up to 2GPa and in magnetic field 0-15T. In the inhomogeneous and paramagnetic regions of the phase diagram the main contribution to the electronic transport is related to the strong static magnetic fluctuations, which arise due to interplay of structural disorder within Gd-sublattice and Co-3d itinerant electron metamagnetism. This complex magnetic disorder brings about novel transport phenomena, such as anomalous positive magnetoresistance found in ferrimagnetic state of the alloys. The low-temperature thermopower is almost independent of alloy composition in the ferrimagnetic range of the phase diagram (x>0.3) indicating that the alloying does not change electronic structure of the compounds in a close vicinity of Fermi energy. However, the thermopower shows substantial variation with the composition in the inhomogeneous and in the paramagnetic regions of the phase diagram reflecting evolution of the magnetic structure with the composition

A pseudoatom in a cage: trimetallofullerene Y(3)@C(80) mimics y(3)n@c(80) with nitrogen substituted by a pseudoatom.

Science.gov (United States)

Popov, Alexey A; Zhang, Lin; Dunsch, Lothar

2010-02-23

Y(3)C(80) obtained in the synthesis of nitride clusterfullerenes Y(3)N@C(2n) (2n = 80-88) by the reactive atmosphere method is found to be a genuine trimetallofullerene, Y(3)@C(80), with low ionization potential and divalent state of yttrium atoms. DFT studies of the electronic structure of Y(3)@C(80) show that this molecule mimics Y(3)N@C(80) with the pseudoatom (PA) instead of the nitrogen atom. Topology analysis of the electron density and electron localization function show that yttrium atoms form Y-PA bonds rather than direct Y-Y bonds. Molecular dynamics simulations show that the Y(3)PA cluster is as rigid as Y(3)N and rotates inside the fullerene cage as a single entity.

A high volume, batch mode {sup 129}Xe polarizer

Energy Technology Data Exchange (ETDEWEB)

Wojna-Pelczar, Anna, E-mail: anna.wojna.pelczar@mail.muni.cz [Central European Institute of Technology, Masaryk University, Brno (Czech Republic); Formerly: Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków (Poland); Pałasz, Tadeusz [Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków (Poland)

2017-06-01

Numerous designs of optical gas polarizers have been proposed, broadening possible applications of the hyperpolarized gases as contrast agents in magnetic resonance imaging. We present a home–made {sup 129}Xe polarizer based on the spin exchange optical pumping method. The polarizer operates under 1 bar of the gas mixture (at the maximum temperature of 160 °C) in a high volume optical cell (5025 cm{sup 3}). Approximately 100 cm{sup 3} of {sup 129}Xe polarized at 1.50±0.37% is produced in a single cycle of polarization. Operation under standard pressure imposes polarization transfer mainly via van der Waals molecules, resulting in the efficient spin exchange between rubidium and {sup 129}Xe atoms. The design, construction and operation of the polarizer are described in details.

Mechanical properties of Mo-Si-B alloys fabricated by using core-shell powder with dispersion of yttria nanoparticles

Science.gov (United States)

Byun, Jong Min; Bang, Su-Ryong; Choi, Won June; Kim, Min Sang; Noh, Goo Won; Kim, Young Do

2017-01-01

In recent years, refractory materials with excellent high-temperature properties have been in the spotlight as a next generation's high-temperature materials. Among these, Mo-Si-B alloys composed of two intermetallic compound phases (Mo5SiB2 and Mo3Si) and a ductile α-Mo phase have shown an outstanding thermal properties. However, due to the brittleness of the intermetallic compound phases, Mo-Si-B alloys were restricted to apply for the structural materials. So, to enhance the mechanical properties of Mo-Si-B alloys, many efforts to add rare-earth oxide particles in the Mo-Si-B alloy were performed to induce the improvement of strength and fracture toughness. In this study, to investigate the effect of adding nano-sized Y2O3 particles in Mo-Si-B alloy, a core-shell powder consisting of intermetallic compound phases as the core and nano-sized α-Mo and Y2O3 particles surrounding the core was fabricated. Then pressureless sintering was carried out at 1400 °C for 3 h, and the mechanical properties of sintered bodies with different amounts of Y2O3 particles were evaluated by Vickers hardness and 3-point bending test. Vickers hardness was improved by dispersed Y2O3 particles in the Mo-Si-B alloy. Especially, Mo-3Si-1B-1.5Y2O3 alloy had the highest value, 589 Hv. The fracture toughness was measured using Mo-3Si-1B-1.5Y2O3 alloy and the value indicated as 13.5 MPa·√m.

Effect of Heat Treatment on Corrosion Behaviors of Mg-5Y-1.5Nd Alloys

Directory of Open Access Journals (Sweden)

Xiumin Ma

2016-01-01

Full Text Available Corrosion behavior of Mg-5Y-1.5Nd alloy was investigated after heat treatment. The microstructure and precipitation were studied by scanning electron microscope (SEM and energy dispersive spectrometer (EDS. The weight loss rates of different samples were arranged as T6-24 h>T6-6 h>T6-14 h>as-cast>T4. The open circuit potential (OCP showed that T4 sample had a more positive potential than that of other samples. The potentiodynamic polarization curves showed that the T6-24 h sample had the highest corrosion current density of 245.362 μA·cm−2, whereas the T4 sample had the lowest at 52.164 μA·cm−2. The EIS results confirmed that the heat treatment reduced the corrosion resistance for Mg-5Y-1.5Nd alloy, because the precipitations acted as the cathode of electrochemical reactions to accelerate the corrosion process. The corrosion rates of different samples were mainly determined by the amount and distribution of the precipitations. The precipitations played dual roles that depended on the amount and distribution. The presence of the phase in the alloys could deteriorate the corrosion performance as it could act as an effective galvanic cathode. Otherwise, a fine and homogeneous phase appeared to be a better anticorrosion barrier.

Ion beam synthesis and characterization of metastable group-IV alloy semiconductors

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Naoto; Hasegawa, Masataka; Hayashi, Nobuyuki; Makita, Yunosuke; Shibata, Hajime [Electrotechnical Lab., Tsukuba, Ibaraki (Japan); Katsumata, Hiroshi; Uekusa, Shin-ichiro

1997-03-01

New Group-IV metastable alloy semiconductors and their heterostructures based on combinations of C-Si-Ge-Sn are recently attracting interest because of feasible new electronic and optoelectronic application in Si-technology and here research works on synthesis and characterization of the epitaxial heterostructures of Si-C, Si-Sn on Si fabricated by ion implantation together either with ion-beam-induced epitaxial crystallization (IBIEC) or solid phase epitaxial growth (SPEG) have been investigated. Formations of layers of Si{sub 1-y}C{sub y} (y=0.014 at peak concentration) on Si(100) have been performed by high-dose implantation of 17 keV C ions and successive IBIEC with 400 keV Ar or Ge ion bombardments at 300-400degC or SPEG up to 750degC. Crystalline growth by IBIEC has shown a lower growth rate in Si{sub 1-y}C{sub y}/Si than in intrinsic Si due mainly to the strain existence, which was observed by the X-ray diffraction (XRD) measurements. Photoluminescence(PL) measurements have revealed I{sub 1} or G line emissions that are relevant to small vacancy clusters or C pair formation, respectively. The crystalline growth of Si{sub 1-z}Sn{sub z} layers by 110 keV {sup 120}Sn ion implantation (z=0.029 and z=0.058 at peak concentration) into Si(100) followed either by IBIEC or by SPEG has been also investigated. PL emission from both IBIEC-grown and SPEG-grown samples with the lower Sn concentration has shown similar peaks to those by ion-implanted and annealed Si samples with intense I{sub 1} or I{sub 1}-related (Ar) peaks. Present results suggest that IBIEC has a feature for the non-thermal equilibrium fabrication of Si-C and Si-Sn alloy semiconductors. (J.P.N.)

Laser and electron beam welding study on niobium based Nb-1Zr-0.1C alloy

International Nuclear Information System (INIS)

Badgujar, B.P.; Kushwaha, R.P.; Tewari, R.; Dey, G.K.

2016-01-01

The refractory metal based alloys are most suitable for the structural applications in high temperature reactors envisaged to operate at temperature higher than 1000°C. The Nb-1Zr-0.1C (wt. %) is being considered for structural applications in the proposed Compact High Temperature Reactors (CHTR). The welding of this alloy is a difficult task due to its reactive nature and higher thermal conductivity. Laser and Electron Beam (EB) welds were produced on sheet of Nb-1Zr-0.1C alloy at various processing parameters and their effects on weld quality was studied by characterizing their optical and SEM micrographs and microhardness profile. The joining efficiency of both welding processes were also studied. The laser welds done in air with argon shielding showed higher hardness values compared to EB welds indicating need for adequate shielding. This study will help to find the optimized welding parameters to produce defect free welds of Nb-1Zr-0.1C alloy. (author)

Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films.

Science.gov (United States)

Yate, Luis; Coy, L Emerson; Aperador, Willian

2017-06-08

In this work we report the hot corrosion properties of binary and ternary films of the Ta-Hf-C system in V 2 O 5 -Na 2 SO 4 (50%wt.-50%wt.) molten salts at 700 °C deposited on AISI D3 steel substrates. Additionally, the mechanical and nanowear properties of the films were studied. The results show that the ternary alloys consist of solid solutions of the TaC and HfC binary carbides. The ternary alloy films have higher hardness and elastic recoveries, reaching 26.2 GPa and 87%, respectively, and lower nanowear when compared to the binary films. The corrosion rates of the ternary alloys have a superior behavior compared to the binary films, with corrosion rates as low as 0.058 μm/year. The combination and tunability of high hardness, elastic recovery, low nanowear and an excellent resistance to high temperature corrosion demonstrates the potential of the ternary Ta-Hf-C alloy films for applications in extreme conditions.

The effect of C concentration on radiation damage in Fe–Cr–C alloys

Energy Technology Data Exchange (ETDEWEB)

Meinander, A., E-mail: andrea.meinander@helsinki.fi [EURATOM-Tekes, Department of Physics, P.O. Box 43, FI-00014 University of Helsinki (Finland); Henriksson, K.O.E. [EURATOM-Tekes, Department of Physics, P.O. Box 43, FI-00014 University of Helsinki (Finland); Björkas, C. [EURATOM-Tekes, Department of Physics, P.O. Box 43, FI-00014 University of Helsinki (Finland); Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, Jülich (Germany); Vörtler, K.; Nordlund, K. [EURATOM-Tekes, Department of Physics, P.O. Box 43, FI-00014 University of Helsinki (Finland)

2013-11-15

Using a recently developed analytical bond-order potential for the complete ternary system, we performed molecular dynamics simulations of the primary radiation damage by displacement cascades in different Fe–Cr–C model alloys. We compared results obtained with this new potential to previous studies employing potentials for the binary Fe–Cr and Fe–C systems. We analysed the effect of C concentration on the number of Frenkel pairs produced by the cascades, as well as on clustering of vacancies and self-interstitial atoms (SIAs), and on the Cr and C content in the defects. The effect of C concentration on defect production was negligible, except at very high concentrations of over 1 at.% C. The main effect was in the Cr content of clustered SIAs, which increased with increasing C concentration.

Synthesis and optical properties of (GaAs)yGe5-2y alloys assembled from molecular building blocks

Science.gov (United States)

Sims, P. E.; Wallace, P. M.; Xu, Chi; Poweleit, C. D.; Claflin, B.; Kouvetakis, J.; Menéndez, J.

2017-09-01

Monocrystalline alloys of GaAs and Ge with compositions (GaAs)yGe5-2y have been synthesized following a chemical vapor deposition approach that promotes the incorporation of Ga and As atoms as isolated donor-acceptor pairs. The structural and optical properties show distinct behavior relative to (GaAs)1-xGe2x counterparts produced by conventional routes. Strong band gap photoluminescence is observed in the 0.5-0.6 eV range for samples whose compositions approach the GaAsGe3 limit for isolated Ga-As pairs. In such samples, the Ge-like Raman modes appear at higher frequencies and are considerably narrower than those observed in samples with higher Ge concentrations. These results suggest that the growth mechanism may favor the formation of ordered phases comprising Ga-As-Ge3 tetrahedra. In contrast with the diamond-to-zincblende ordering transition previously reported for III-V-IV alloys, ordered structures built from Ga-As-Ge3 tetrahedra feature III-III and V-V pairs as third-nearest neighbors, and therefore both the III- and V-components are equally present in each of two fcc sublattices of the average diamond-like structure. These bonding arrangements likely lead to the observed optical response, indicating potential applications of these materials in mid-IR technologies integrated on Si.

Influence of 45S5 Bioglass addition on microstructure and properties of ultrafine grained (Mg-4Y-5.5Dy-0.5Zr) alloy

Energy Technology Data Exchange (ETDEWEB)

Kowalski, K., E-mail: kamil.kowalski@put.poznan.pl [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland); Jurczyk, M.U. [Division of Mother’s and Child’s Health, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Wirstlein, P.K. [Department of Gynecology and Obstetrics, Division of Reproduction, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Jakubowicz, J.; Jurczyk, M. [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland)

2017-05-15

Highlights: • Ultrafine grained composites were formed by consolidating mechanically alloyed powders. • Mechanical properties were sensitive to the content of 45S5 Bioglass in Mg-4Y-5.5Dy-0.5Zr alloy. • Fluoride treated composites displayed superior corrosion resistance in Ringer solution. • Composites modified with MgF{sub 2} have a higher degree of biocompatibility in comparison with the unmodified reference material. - Abstract: Bulk samples of an ultrafine grained (Mg-4Y-5.5Dy-0.5Zr)-x wt% 45S5 Bioglass (x = 0, 5) and (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass-1 wt% Ag composites have been synthesized by consolidating mechanically alloyed powders. The influence of the chemical composition on the microstructure, mechanical properties and corrosion behavior of bulk composites were studied. The sintering of (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass powders led to the formation of a bulk composite with grain size of approx. 95 nm. The corrosion behavior of Mg-based composites before and after hydrofluoric acid treatment was also investigated. The ultrafine grained (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass composite was more corrosion resistant than the bulk Mg-4Y-5.5Dy-0.5Zr alloy after HF treatment. The in vitro biocompatibility of synthesized composites was evaluated and compared with microcrystalline magnesium. Magnesium, (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass and (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass-1 wt% Ag composites modified with MgF{sub 2} have a higher degree of biocompatibility in comparison with the unmodified reference material.

Production of NbC reinforced aluminum matrix composites by mechanical alloying

International Nuclear Information System (INIS)

Silva, Marina Judice; Cardoso, Katia Regina; Travessa, Dilermando Nagle

2014-01-01

Aluminum and their alloys are key materials for the automotive and aerospace industries. The dispersion of hard ceramic particles in the Al soft matrix produces lightweight composites with interesting properties, as environmental resistance, high specific strength and stiffness, high thermal and electrical conductivity, and good wear resistance, encouraging their technological use. Powder metallurgy techniques like mechanical alloying (MA) are very attractive to design metal matrix composites, as they are able to achieve a homogeneous distribution of well dispersed particles inside the metal matrix. In this work, pure aluminum has been reinforced with particles of Niobium carbide (NbC), an extremely hard and stable refractory ceramic. NbC is frequently used as a grain growth inhibitor in micro-alloyed steel due to their low solubility in austenite. In the present work, NbC is expected to act as a reinforcing phase by its fine dispersion into the aluminum matrix, produced by MA. Composite powders produced after different milling times (up to 50h), with 10 and 20% (volume) of NbC were characterized by diffraction laser particle size analysis, scanning electron microscopy (SEM) and by X-ray diffraction (DRX), in order to establish a relationship between the milling time and the characteristics of the powder produced, as size and morphology, crystallite size and reinforcement distribution. This characterization is important in defining the MA process for production of composites for further consolidation by hot extrusion process. (author)

Production of NbC reinforced aluminum matrix composites by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Silva, Marina Judice; Cardoso, Katia Regina; Travessa, Dilermando Nagle, E-mail: dilermando.travessa@unifesp.br [Universidade Federal de Sao Paulo (UNIFESP), Sao Jose dos Campos, SP (Brazil). Instituto de Ciencia e Tecnologia

2014-07-01

Aluminum and their alloys are key materials for the automotive and aerospace industries. The dispersion of hard ceramic particles in the Al soft matrix produces lightweight composites with interesting properties, as environmental resistance, high specific strength and stiffness, high thermal and electrical conductivity, and good wear resistance, encouraging their technological use. Powder metallurgy techniques like mechanical alloying (MA) are very attractive to design metal matrix composites, as they are able to achieve a homogeneous distribution of well dispersed particles inside the metal matrix. In this work, pure aluminum has been reinforced with particles of Niobium carbide (NbC), an extremely hard and stable refractory ceramic. NbC is frequently used as a grain growth inhibitor in micro-alloyed steel due to their low solubility in austenite. In the present work, NbC is expected to act as a reinforcing phase by its fine dispersion into the aluminum matrix, produced by MA. Composite powders produced after different milling times (up to 50h), with 10 and 20% (volume) of NbC were characterized by diffraction laser particle size analysis, scanning electron microscopy (SEM) and by X-ray diffraction (DRX), in order to establish a relationship between the milling time and the characteristics of the powder produced, as size and morphology, crystallite size and reinforcement distribution. This characterization is important in defining the MA process for production of composites for further consolidation by hot extrusion process. (author)

Simulación numérica de la descomposición espinodal en sistemas de aleación hipotéticos A-B y A-B-C

Directory of Open Access Journals (Sweden)

Avila-Dávila, E. O.

2012-06-01

Full Text Available The phase field method is based on the thermodynamics, mechanism and kinetic of the precipitation reactions in alloys. This method can be used to simulate numerically the microstructural evolution in an alloy system, and constitutes a powerful tool to predict the phase transformations. The phase field method solves the nonlinear Cahn- Hilliard partial differential equation and offers computational advantages. The effect of the parameters into this equation on the morphology and kinetics of the phase separation in binary A-B and ternary A-B-C hypothetical alloy systems with a miscibility gap was analyzed. The results showed that the atomic mobility modifies the phase separation kinetics. In contrast, elastic-strain energy is an important parameter that affects the morphology of phases causing changes from spheres to cuboids or plates with preferential crystallographic alignment.

El Método de Campo de Fases, basado en fundamentos de termodinámica, mecanismos y cinética de reacciones de precipitación en aleaciones, es útil para simular numéricamente la solidificación de aleaciones de interés industrial, su microestructura y su evolución durante ciclos térmicos. Este método resuelve la ecuación diferencial parcial de Cahn y Hilliard y ofrece como ventajas su sencillez y rapidez computacional. En este trabajo se analizó el efecto de los parámetros que intervienen en tal ecuación sobre la morfología y cinética de la separación de fases de sistemas de aleación hipotéticos A-B y A-B-C con laguna de inmiscibilidad. Los resultados obtenidos mostraron que los cambios en la movilidad atómica modifican la cinética de la separación. En contraste, la energía de deformación elástica afecta directamente la morfología de las fases, causando que la morfología pase de esferas a cubos con bordes redondeados o placas con alineación cristalográfica preferencial.

Relationship of microstructure and mechanical properties for V-Cr-Ti alloys

International Nuclear Information System (INIS)

Loomis, B.A.; Gazda, J.; Nowicki, L.J.; Smith, D.L.; Danyluk, S.

1993-08-01

Relation of composition, number density, and diameter of precipitates in microstructures of unalloyed V and V-Cr-Ti alloys to the yield strength, hardness, creep stress, and ductile-brittle transition temperature (DBTT) for these materials was determined from analytical electron microscopy analyses of precipitates in these materials and from mechanical properties data. Unalloyed V and V-Cr-Ti alloys with ≤3 wt. % Ti contained VC and TI(CNO) precipitates that were coherent with the matrix. The most common precipitates in the alloys were Ti(C 1-x-y N x O y ) that were non-coherent with the matrix. The number density of non-coherent precipitates was maximum in V-3Ti and V-5Cr-3Ti alloys, and the average diameter of non-coherent precipitates was minimum in V-(1--3)Ti and V-5Cr-3Ti alloys. The increase of yield strength and hardness of V on alloying with Ti and Cr was shown to be primarily due to coherent precipitate, solute-atom misfit, and shear-modulus difference effects. The creep stress for rupture in 1000 hours was related to the number density of precipitates, whereas the DBTT was related to the volume fraction of precipitates

Irradiation performance of oxide dispersion strengthened copper alloys to 150 dpa at 415 degree C

International Nuclear Information System (INIS)

Edwards, D.J.; Kumar, A.S.; Anderson, K.R.; Stubbins, J.F.; Garner, F.A.; Hamilton, M.L.

1991-11-01

Results have been obtained on the post-irradiation properties of various oxide dispersion strengthened copper alloys irradiated from 34 to 150 dpa at 415 degrees C in the Fast Flux Test Facility. The GlidCop alloys strengthened by Al 2 O 3 continue to outperform other alloys with respect to swelling resistance, and retention of both electrical conductivity and yield strength. Several castable ODS alloys and a Cr 2 O 3 -strengthened alloy show increasingly poor resistance to radiation, especially in their swelling behavior. A HfO 2 -strengthened alloy retains most of its strength and its electrical conductivity reaches a constant level after 50 dpa, but it exhibits a higher residual radioactivity

Surface Modification Technology of ODS Alloying Treatment by using Laser Heat Source

International Nuclear Information System (INIS)

Kim, H. G.; Kim, I. H.; Choi, B. K.; Park, J. Y.; Koo, Y. H.

2012-01-01

The ODS (Oxide Dispersion Strengthed) alloys can be applied as structural materials for components in the core of a nuclear power plants since these components must have a high mechanical strength at high temperature up to 700 .deg. C. This type of alloy was generally manufactured by mechanical alloying from its source metal and Y 2 O 3 powders. The mechanical alloyed powder is subjected to the HIP (Hot Isotatic Pressing) or hot extrusion: and this product is heat treated at target temperature and time. Thus, the Y 2 O 3 particles are dispersed in the metal matrix. These manufacturing process of ODS alloy is very complex and expensive. Also, it is necessary the special techniques to obtain the uniform dispersion and volume control of Y 2 O 3 particles. Another problem is the final product forming such as tube and sheet because the intermediated-product has a high mechanical strength due to the dispersion of Y 2 O 3 particles. The laser cladding techniques was applied on the surface cladding of ceramics and inter-metallic compounds on metal base and ceramic base components to increase corrosion and wear resistance. The laser heat source can be used to the alloying the metal and ceramic materials, because thermally melting of metal and ceramic is possible. So, we are applied on ODS alloy manufacturing by using the laser heat source. The main advantages and disadvantage of this technology can be resumed as follows: · It is possible to apply to the sheet and tube shape component, directly. · Metallurgical damage such as HAZ and severe grain growth is considerably reduced. · Good control of the alloying element of the treated zone · Highly reproducible homogeneous zone · The pores and cracks are suppressed in the treated zone · Oxidation can be prevented during the process. · Good control is possible for the irregular shaped components. · The bulk material alloying is limited by the power of laser source. So, this work is studied on the ODS alloy manufacturing

Evaluation of Pb–17Li compatibility of ODS Fe-12Cr-5Al alloys

Energy Technology Data Exchange (ETDEWEB)

Unocic, Kinga A., E-mail: unocicka@ornl.gov; Hoelzer, David T.

2016-10-15

The Dual Coolant Lead Lithium (DCLL: eutectic Pb–17Li and He) blanket concept requires improved Pb–17Li compatibility with ferritic steels in order to demonstrate acceptable performance in fusion reactors. As an initial step, static Pb-17at.%Li (Pb-17Li) capsule experiments were conducted on new oxide dispersion strengthened (ODS) FeCrAl alloys ((1) Y{sub 2}O{sub 3} (125Y), (2) Y{sub 2}O{sub 3} + ZrO{sub 2} (125YZ), (3) Y{sub 2}O{sub 3} + HfO{sub 2} (125YH), and (4) Y{sub 2}O{sub 3} + TiO{sub 2} (125YT)) produced at ORNL via mechanical alloying (MA). Tests were conducted in static Pb–17Li for 1000 h at 700 °C. Alloys showed promising compatibility with Pb–17Li with small mass change after testing for 125YZ, 125YH and 125YT, while the 125Y alloy experienced the highest mass loss associated with some oxide spallation and subsequent alloy dissolution. X-ray diffraction methods identified the surface reaction product as LiAlO{sub 2} on all four alloys. A small decrease (∼1 at.%) in Al content beneath the oxide scale was observed in all four ODS alloys, which extended 60 μm beneath the oxide/metal interface. This indicates improvements in alloy dissolution by decreasing the amount of Al loss from the alloy. Scales formed on 125YZ, 125YH and 125YT were examined via scanning transmission electron microscopy (S/TEM) and revealed incorporation of Zr-, Hf-, and Ti-rich precipitates within the LiAlO{sub 2} product, respectively. This indicates an inward scale growth mechanism. Future work in flowing Pb–17Li is needed to further evaluate the effectiveness of this strategy in a test blanket module. - Highlights: • Investigation of Pb-17Li compatibility of new ODS Fe-12Cr5Al. • Promising small mass change after static Pb-17Li exposure. • LiAlO{sub 2} formed on the surface during Pb-17Li exposure. • Oxide precipitates incorporated within the LiAlO{sub 2} product. • An inward scale growth mechanism was identified.

Low cycle fatigue behaviors of low alloy steels in 310 .deg. C deoxygenated water

International Nuclear Information System (INIS)

Jang, Hun

2008-02-01

After low cycle fatigue tests of SA508 Gr.1a low alloy steel in 310 .deg. C deoxygenated water, the fatigue surface and the sectioned area of specimens were observed to understand the effect of the cyclic strain rate on the environmentally assisted cracking behaviors. From the fatigue crack morphologies of the specimen tested at a strain rate of 0.008 %/s, unclear ductile striations and blunt crack tip were observed. So, metal dissolution could be the main cracking mechanism of the material at the strain rate. On the other hand, on the fatigue surface of the specimen tested at strain rates of 0.04 and 0.4 %/s, the brittle cracks and the flat facets, which are the evidence of the hydrogen induced cracking, were observed. Also, the tendency of linkage between the main crack and micro-cracks was observed on the sectioned area. Therefore, the main cracking mechanism at the strain rates of 0.04 and 0.4 %/s could be the hydrogen induced cracking. Additionally, the evidence of the dissolved MnS inclusions was observed on the fatigue surface from energy dispersive x-ray spectrometer analyses. So, despite of the low sulfur content of the test material, the sulfides seem to contribute to environmentally assisted cracking of SA508 Gr.1a low alloy steel in 310 .deg. C deoxygenated water. Additionally, our experimental fatigue life data of SA508 Gr.1a low alloy steel (heat A) showed a consistent difference with statistical model produced in argon national laboratory. So, additional low cycle fatigue tests of other heat SA508 Gr.1a (heat B) and SA508 Gr.3 low alloy steels were performed to investigate the effect of material variability on fatigue behaviors of low alloy steels in 310 .deg. C deoxygenated water. In results, the fatigue lives of three low alloy steels were increased following order: SA508 Gr.1a low alloy steel - heat A, SA508 Gr.3 low alloy steel, and SA508 Gr.1a low alloy steel - heat B. From microstructure observation, the fatigue surface of SA508 Gr.1a low alloy

Corrosion properties and corrosion evolution of as-cast AZ91 alloy with rare earth yttrium

International Nuclear Information System (INIS)

Luo, T.J.; Yang, Y.S.

2011-01-01

Highlights: → Minor addition of Y will increase the corrosion resistance of AZ91 alloy, and 0.3 wt.% Y is the optimum addition. → A film composed of Mg(OH) 2 , MgCO 3 , Al(OH) 3 and Al 2 O 3 is formed on the surface of AZ91 alloy with rare earth Y free. → The film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH) 2 and MgCO 3 without any Al(OH) 3 and Al 2 O 3 . → The relative quantity of MgCO 3 in the surface film of AZ91 + 0.3 wt.% Y is bigger than that of AZ91 alloy with Y free. → Y 2 O 3 phase is found in the surface film of alloy III, which benefits to stabilize the surface film. -- Abstract: The corrosion resistance property and the corrosion evolution of as-cast AZ91 alloy with rare earth Y addition are investigated by using immersion tests, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The results show that the proper amount of Y in the alloys can improve the corrosion resistance of AZ91 alloys effectively. With the increment of Y, the corrosion rate of the modified AZ91 alloys by Y addition was markedly less than that of AZ91 alloy. The corrosion rate of AZ91 alloy with 0.3 wt.% Y was the slightest, but further addition of Y content over 0.3 wt.% make the corrosion heavier. The XPS analysis suggests that the compound film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH) 2 and MgCO 3 without any Al(OH) 3 and Al 2 O 3 , in addition, Y 2 O 3 phase is found in the compound film of AZ91 alloy with 0.3 wt.% Y, which benefits to stabilize the surface film.

The effect of carbon distribution on deformation and cracking of Ni-16Cr-9Fe-C alloys

International Nuclear Information System (INIS)

Hertzberg, J.L.; Was, G.S.

1995-01-01

Constant extension rate tensile (CERT) tests and constant load tensile (CLT) tests were conducted on controlled purity Ni-16Cr-9Fe-C alloys. The amount and form of carbon were varied in order to investigate the roles of carbon in solution and as intergranular (IG) carbides in the deformation and IG cracking behavior in 360 C argon and primary water environments. Results show that the strength, ductility and creep resistance of these alloys are increased with carbon present in solid solution, while IG cracking on the fracture surface is suppressed. Alloys containing carbon in the form of IG carbides, however, exhibit reduced strength and ductility relative to carbon in solution, while maintaining high IG cracking resistance with respect to carbon-free alloys. CERT results of commercial alloy 600 and controlled purity, carbon containing alloys yield comparable failure strains and IG cracking amounts. CLT comparisons with creep tests of alloy 600 suggest that alloys containing IG carbides are more susceptible to creep than those containing all carbon in solid solution

Isothermal and cyclic oxidation resistance of pack siliconized Mo–Si–B alloy

Energy Technology Data Exchange (ETDEWEB)

Majumdar, Sanjib, E-mail: sanjib@barc.gov.in

2017-08-31

Highlights: • Pack-siliconizing of Mo–Si–B alloy improves its oxidation resistance at 750, 900 and 1400 °C. • A marginal weight change of the coated alloy is detected in isothermal and cyclic oxidation tests. • Kinetics of growth of protective SiO{sub 2} scale is much faster at 1400 °C. • Self-healing SiO{sub 2} is developed at the cracks formed in MoSi{sub 2} layer during cyclic oxidation tests. - Abstract: Oxidation behaviour of MoSi{sub 2} coated Mo–9Si–8B–0.75Y (at.%) alloy has been investigated at three critical temperatures including 750, 900 and 1400 °C in static air. Thermogravimetric analysis (TGA) data indicates a remarkable improvement in the oxidation resistance of the silicide coated alloy in both isothermal and cyclic oxidation tests. The cross-sectional scanning electron microscopy and energy dispersive spectroscopic analysis reveal the occurrence of internal oxidation particularly at the crack fronts formed in the outer MoSi{sub 2} layer during thermal cycling. The dominant oxidation mechanisms at 750–900 °C and 1400 °C are identified. Development of MoB inner layer further improves the oxidation resistance of the silicide coated alloy.

Compacting the powder of Al-Cr-Mn Alloy with SPS

Czech Academy of Sciences Publication Activity Database

Kubatík, Tomáš František; Pala, Zdeněk; Novák, P.

2015-01-01

Roč. 49, č. 1 (2015), s. 129-132 ISSN 1580-2949 Institutional support: RVO:61389021 Keywords : aluminium alloy * intermetallics * powder metalurgy * spark-plasma sintering Subject RIV: JG - Metallurgy Impact factor: 0.439, year: 2015 http://mit.imt.si/Revija/izvodi/mit151/kubatik.pdf

Heat treatment effect on the properties of welded joint of niobium alloys of the Nb-1Zr-C system

International Nuclear Information System (INIS)

Aref'ev, Yu.V; Chernyshova, T.A.; Pokosov, V.S.

1976-01-01

Thermal treatment of weld joints of the alloys Nb-1 Zr-(0.01-0.12)C at 800-900 deg C leads to decomposition of the solid solution of the weld metal which is accompanied with a decrease in plasticity and impact strength. The decomposition of the solid solution takes place even in a relatively pure alloy containing only 0.025% of intrusion impurities. Thermal treatment is reasonable only when carbon content in the alloys is no less than 0.1%. The decomposition of the solid solution in the weld metal of the alloy containing 0.12% of C takes place during thermal treatment at the expense of liberating niobium carbides Nb 3 C 2 and Nb 2 C. When rearrangement takes place, i it is Nb 2 C that liberates mainly

Self propagating high temperature synthesis (SHS) of the Fe(TiMo)C master alloy using ferroalloys

International Nuclear Information System (INIS)

Erauskin, J. I.; Sargyan, A.; Arana, J. L.

2009-01-01

Titanium monocarbide TiC is very hard, stable both at high and low temperatures and relatively easy to synthesize from its constituent elements by SHS. Nevertheless, it is difficult to use, as alloying element, in the reinforcement of steels manufactured by liquid metallurgy due to its low wettability by molten steel. To achieve this purpose and due to its better wettability, it is more appropriate to use a master alloy formed by the complex carbide (TiMo)C bonded in Fe. The simplest and most economic way to fabricate such a master alloy Fe(TiMo)C is, again, by SHS, with the added advantage that it can be manufactured using the commercial ferroalloys FeTi and FeMo instead of the individual elements Fe, Ti and Mo. In this work, we describe such a process as well as the characteristics of the master alloy obtained. (Author) 13 refs

I-129 migration and retrospective dosimetry

International Nuclear Information System (INIS)

Daraoui, Abdelouahed

2010-01-01

The naturally occurring of the long-lived radionuclide 129 I (T 1/2 = 15.7 Ma) have been substantially increased by the fallout from atmospheric nuclear explosions, by releases from nuclear accidents and by emissions from reprocessing plants. The aim of this study was to determine the 127 I, 129 I, 40 K and 137 Cs in Soils from Northern Ukraine, Chile, Bavaria and the Retrospective Dosimetry of the 131 I exposure after the Chernobyl Accident. In addition, water samples from North Germany (precipitation, surface and ground waters, Aerosol, soils, Humus and milk), North Sea, North Atlantic, Spitzbergen, Indian Ocean, Mediterranean, Hawaii, Tahiti, Egypt and prenuclear sediment samples of the Baltic Sea and the North Sea were analysed. 129 I/ 127 I was analysed by accelerator mass spectrometry (AMS) and 127 I was determined by inductively coupled plasma mass spectrometry (ICP-MS). The geometric mean deposition density of 129 I in these soils was 109 x 1.5 ±1 mBq m -2 , that the dominant sources of 129 I in the region are the reprocessing plants (La Hague and Sellafield) and not the Chernobyl fallout. The 129 I/ 127 I isotopic ratios of the Bavarian soils are measured between 10 -7 and 10 -10 what is 100- to 1000-time higher than as the ratios obtained for the Chilean samples. The 129 I integral deposition densities in Chile, Easter Island and Antarctica were between 0.3 and 2 mBq m -2 . In these soils the observed 129 I/ 127 I ratios are about 10 -12 low measured Value in the pedosphere. This value is consistent with the results from the marine sediments assumed to represent the pre-nuclear equilibrium ratios. The soils from Chile also allow the determination of the 129 I fallout from the atmospheric nuclear weapons explosions undisturbed from contaminations due to the releases from reprocessing plants. The results from the soil profiles show that more than 90 % of the 129 I-concentration in the soil profiles are still in the top 40 cm of the profiles is located

High-Throughput Screening Across Quaternary Alloy Composition Space: Oxidation of (AlxFeyNi1-x-y)∼0.8Cr∼0.2.

Science.gov (United States)

Payne, Matthew A; Miller, James B; Gellman, Andrew J

2016-09-12

Composition spread alloy films (CSAFs) are commonly used as libraries for high-throughput screening of composition-property relationships in multicomponent materials science. Because lateral gradients afford two degrees of freedom, an n-component CSAF can, in principle, contain any composition range falling on a continuous two-dimensional surface through an (n - 1)-dimensional composition space. However, depending on the complexity of the CSAF gradients, characterizing and graphically representing this composition range may not be straightforward when n ≥ 4. The standard approach for combinatorial studies performed using quaternary or higher-order CSAFs has been to use fixed stoichiometric ratios of one or more components to force the composition range to fall on some well-defined plane in the composition space. In this work, we explore the synthesis of quaternary Al-Fe-Ni-Cr CSAFs with a rotatable shadow mask CSAF deposition tool, in which none of the component ratios are fixed. On the basis of the unique gradient geometry produced by the tool, we show that the continuous quaternary composition range of the CSAF can be rigorously represented using a set of two-dimensional "pseudoternary" composition diagrams. We then perform a case study of (AlxFeyNi1-x-y)∼0.8Cr∼0.2 oxidation in dry air at 427 °C to demonstrate how such CSAFs can be used to screen an alloy property across a continuous two-dimensional subspace of a quaternary composition space. We identify a continuous boundary through the (AlxFeyNi1-x-y)∼0.8Cr∼0.2 subspace at which the oxygen uptake into the CSAF between 1 and 16 h oxidation time increases abruptly with decreasing Al content. The results are compared to a previous study of the oxidation of AlxFeyNi1-x-y CSAFs in dry air at 427 °C.

Joining of yttria-tetragonal zirconia polycrystal with an aluminum-zirconium alloy

International Nuclear Information System (INIS)

Rathner, R.C.; Green, D.J.

1990-01-01

Specimens of yttria-tetragonal zirconia polycrystal (Y-TZP) have been joined with an Al-5.8 wt% Zr alloy at temperatures of 900 degrees C and above. The braze alloy contained large needlelike precipitates of the intermetallic phase Al 3 Sr. It is shown that these large precipitates can aid in strengthening of the joint, especially if they are close to the interface. With decreasing layer thickness, the strengths increased with values as high as 420 MPa

The response of dispersion-strengthened copper alloys to high fluence neutron irradiation at 415 degrees C

International Nuclear Information System (INIS)

Edwards, D.J.; Newkirk, J.W.; Garner, F.A.; Hamilton, M.L.; Nadkarni, A.; Samal, P.

1993-01-01

Various oxide-dispersion-strengthened copper alloys have been irradiated to 150 dpa at 415 degrees C in the Fast Flux Test Facility (FFTF). The Al 2 O 3 -strengthened GlidCop TM alloys, followed closely by a HfO 2 -strengthened alloy, displayed the best swelling resistance, electrical conductivity, and tensile properties. The conductivity of the HfO 2 -strengthened alloy reached a plateau at the higher levels of irradiation, instead of exhibiting the steady decrease in conductivity observed in the other alloys. A high initial oxygen content results in significantly higher swelling for a series of castable oxide-dispersion-strengthened alloys, while a Cr 2 O 3 -strengthened alloy showed poor resistance to radiation

Effect of thermal cycling on the microstructure of a directionally solidified Fe, Cr, Al-TaC eutectic alloy

Science.gov (United States)

Harf, F. H.; Tewari, S. N.

1977-01-01

Cylindrical bars (1.2 cm diameter) of Fe-13.6Cr-3.7Al-9TaC (wt %) eutectic alloy were directionally solidified in a modified Bridgman type furnace at 1 cm/h. The alloy microstructure consisted of aligned TaC fibers imbedded in a bcc Fe-Cr-Al matrix. Specimens of the alloy were thermally cycled from 1100 to 425 C in a burner rig. The effects of 1800 thermal cycles on the microstructure was examined by scanning electron microscopy, revealing a zig-zag shape of TaC fibers aligned parallel to the growth direction. The mechanism of carbide solution and reprecipitation on the (111) easy growth planes, suggested previously to account for the development of irregular serrations in Co-Cr-Ni matrix alloys, is believed to be responsible for these zig-zag surfaces.

7 CFR 1260.129 - Customs Service.

Science.gov (United States)

2010-01-01

... 7 Agriculture 10 2010-01-01 2010-01-01 false Customs Service. 1260.129 Section 1260.129... Promotion and Research Order Definitions § 1260.129 Customs Service. Customs Service means the United States Customs Service of the United States Department of the Treasury. ...

9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

International Nuclear Information System (INIS)

Rojas Jara, David

2011-01-01

This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M 23 C 6 carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M 23 C 6 precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure evolution and creep

9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

Energy Technology Data Exchange (ETDEWEB)

Rojas Jara, David

2011-03-21

This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6} carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure

Diffusion of titanium and niobium in b.c.c. Ti--Nb alloys

International Nuclear Information System (INIS)

Pontau, A.E.

1978-01-01

The diffusion coefficients for titanium and niobium radioactive tracers were simultaneously measured in Ti, Ti 94 6 Nb 5 4 , Ti 80 4 Nb 19 6 , and Ti 64 3 Nb 35 . 7 over the temperature range from 950 0 C to 1511 0 C using standard lathe sectioning techniques. The samples were initially heat treated by annealing above the α-β phase transition temperature and then either cooling slowly to room temperature or quenching. The room temperature crystal morphology was then examined using x-ray diffraction. Alloy concentrations were chosen both to suppress the β-α transition and to obtain the metastable ω-phase

Transformaciones de fase en aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag envejecidas isotérmicamente

Directory of Open Access Journals (Sweden)

Flores-Ramos, Alfredo

2014-12-01

Full Text Available The study of phase transformations that take place in Zn-22%Al-2%Cu and Zn-22%Al-2%Cu-X (X = 1, 2 and 3%Ag alloys was carried out using X-Ray Diffraction (XRD and Scanning Electron Microscopy (SEM. Alloys were homogenized at 350 °C during 10 days and quenched at ~2 °C. Subsequently, samples were aged at 200 °C for different times. The initial microstructure consists in a matrix of fine equiaxial grains of α and η phases for all the alloys. Besides isolated particles of ε and Φ were observed without and with Ag addition, respectively. During the aging, the four phase reaction, α + ε→η + τ’, takes place to obtain the equilibrium η, α and τ’ phases. However, the Ag addition promotes the formation of the Φ phase, which retards or inhibits the four phase reaction. The stability of the Φ phase is obtained with 3%Ag, which could improve the dimensional stability of the alloy for future industrial applications.En el presente estudio sobre las transformaciones de fase en las aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag se utilizó Difracción de Rayos X (DRX y Microscopía Electrónica de Barrido (MEB. Las aleaciones fueron homogeneizadas a 350 °C durante 10 días, templadas a ~2 °C y posteriormente envejecidas a 200 °C durante diferentes tiempos. Todas las aleaciones ensayadas presentaron una microestructura inicial formada por una matriz de granos finos y equiaxiales de las fases α y η. Además, para las aleaciones sin Ag se observa la presencia de partículas de la fase ε (CuZn4 y de Φ ((Ag, Cu Zn4 en las que se adicionó Ag. Durante el envejecido, ocurre la reacción de cuatro fases, α + ε→η + τ’, para obtener las fases de equilibrio η, α y τ’. Sin embargo, la adición de Ag promueve la formación de la fase Φ, la cual retarda e incluso inhibe la reacción de cuatro fases. La estabilidad de la fase Φ se obtiene con 3%Ag, lo que podría mejorar la estabilidad dimensional de la aleación para

Measurement of surface-induced microplasticity in Alloy 600 C-rings

International Nuclear Information System (INIS)

Lo, C.F.; Kamide, H.; Mayo, W.E.; Weissmann, S.

1990-03-01

The level of microplasticity in Alloy 600 specimens used for accelerated SCC tests was measured with the aid of a novel x-ray rocking curve technique developed at Rutgers University. With this tool, it was possible to measure quantitatively the strain level at any point along the circumference of a C-ring. Combined with selective etching, the method was used to obtain a depth profile of the strain. A detailed study of the deformation state in C-rings was performed with a particular emphasis on how material parameters influence localization of the strain. These studies included the role of grain boundary carbides, grain size and mill anneal temperatures. The studies led to the development of a numerical model for calculation of the strain distribution along a C-ring which is superior to that currently in use. An additional result of these studies was a simple indirect method that can be used to determine the amount of grain boundary carbides present in tubes of Alloy 600. The final phase of this project was to measure the strain relaxation kinetics in this alloy. From this work, the activation energy for relaxation and the atomistic process responsible were identified. Based on this work, calculations were performed to indicate the degree of relaxation that can be expected during normal steam generator operation and accelerated SCC testing. These calculations suggest that relaxation may be significant in the temperature range of 280--360 degree C which is typical for such tests and highlights the fact that during these tests significant changes in the microstructure that can be detected by x-rays are taking place. These results will provide a more accurate basis for extrapolating tests to actual steam generator corrosion experience. 6 figs., 2 tabs

Environmental concentration and migration of 129I

International Nuclear Information System (INIS)

Brauer, F.P.; Strebin, R.S. Jr.

1982-01-01

Local sources of 129 I suitable for study of migration in the environment are uranium ore bodies for long periods and nuclear fuel reprocessing operations for recent periods. Uranium ores produce 129 I from spontaneous and neutron-induced fission. Nuclear fuel reprocessing has resulted in releases of 129 I to both the atmosphere and the hydrosphere. The long-term fate of surface-deposited and groundwater 129 I was studied. Neutron activation analysis was used to measure the low levels of 129 I and natural 127 I in samples near and remote from nuclear fuel reprocessing facilities. Measurements were made on air samples, vegetation, soil, surface water, groundwater and uranium ore samples. Samples were collected both during reprocessing operations and after reprocessing activities had been discontinued for several years. The 129 I was found to accumulate in the top soil and litter layer. The surface concentrations of 129 I in forest communities were found to be several times higher than for nearby grass communities. The 129 I levels were found to persist in the environment after reprocessing activities had been discontinued. Measurable 129 I was found to be contained in uranium ore samples from a variety of locations and with a range of uranium concentrations. Thus ore bodies constitute a source of 129 I suitable for study of migration over long periods. Iodine-129 has entered surface and groundwater as the result of liquid and atmospheric discharges from nuclear fuel reprocessing facilities. The iodine in water samples was found to be anionic and travel with the water flow. Thus 129 I was found to provide high sensitivity for hydrology tracer studies and radioactivity migration surveillance. Once 129 I enters the hydrosphere it migrates with the water with little or no hold-up by exchange with cationic exchangers such as soil or silt

46 CFR 129.220 - Basic safety.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Basic safety. 129.220 Section 129.220 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS ELECTRICAL INSTALLATIONS General Requirements § 129.220 Basic safety. (a) Electrical equipment and installations must be suitable...

Investigation of structural, electronic, elastic and optical properties of Cd{sub 1-x-y}Zn{sub x}Hg{sub y}Te alloys

Energy Technology Data Exchange (ETDEWEB)

Tamer, M., E-mail: mehmet.tamer@zirve.edu.tr [Zirve University Faculty of Education, 27260, Gaziantep (Turkey)

2016-06-15

Structural, optical and electronic properties and elastic constants of Cd1{sub -x-y}Zn{sub x} Hg{sub y}Te alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers–Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard’s law. It is seen that results obtained from theory and experiments are all in agreement.

Impact strength of the uranium-6 weight percent niobium alloy between -1980 and +2000C

International Nuclear Information System (INIS)

Anderson, R.C.

1981-09-01

A study was conducted to determine if a ductile-to-brittle transition wxisted for the uranium-6 wt % niobium (U-6Nb) alloy. Standard V-notched Charpy bars were made from both solution-quenched and solution-quenched and aged U-6Nb alloy and were tested between -198 0 and +200 0 C. It was found that a sharp ductile-brittle transition does not exist for the alloy. A linear relationship existed between test temperature and impact strength, and the alloy retained a significant amount of impact strength even at very low temperatures. 9 figures

Simultaneous aluminizing and chromizing of steels to form (Fe,Cr){sub 3}Al coatings and Ge-doped silicide coatings of Cr-Zr base alloys

Energy Technology Data Exchange (ETDEWEB)

Zheng, M.; He, Y.R.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

1997-12-01

A halide-activated cementation pack involving elemental Al and Cr powders has been used to achieve surface compositions of approximately Fe{sub 3}Al plus several percent Cr for low alloy steels (T11, T2 and T22) and medium carbon steel (1045 steel). A two-step treatment at 925 C and 1150 C yields the codeposition and diffusion of aluminum and chromium to form dense and uniform ferrite coatings of about 400 {micro}m thickness, while preventing the formation of a blocking chromium carbide at the substrate surfaces. Upon cyclic oxidation in air at 700 C, the coated steel exhibits a negligible 0.085 mg/cm{sup 2} weight gain for 1900 one-hour cycles. Virtually no attack was observed on coated steels tested at ABB in simulated boiler atmospheres at 500 C for 500 hours. But coatings with a surface composition of only 8 wt% Al and 6 wt% Cr suffered some sulfidation attack in simulated boiler atmospheres at temperatures higher than 500 C for 1000 hours. Two developmental Cr-Zr based Laves phase alloys (CN129-2 and CN117(Z)) were silicide/germanide coated. The cross-sections of the Ge-doped silicide coatings closely mimicked the microstructure of the substrate alloys. Cyclic oxidation in air at 1100 C showed that the Ge-doped silicide coating greatly improved the oxidation resistance of the Cr-Zr based alloys.