Papers by Keyword: Iron Aluminide

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Authors: Aneta Hanc, Jerzy Kansy
Abstract: In this work, Mössbauer spectroscopy and X-ray powder diffraction (XRD) are used in a study of point defect formation in intermetallic phases of the B2 structure of the Fe-Al system as a function of Al concentration. The results are compared with the concentrations of point defect determined from positron annihilation data. In the Mössbauer effect, two types of samples are investigated: Fe-Al alloys with few additives obtained by induction melting and Al-rich metallic powders produced by the self-decomposition method and intensive grinding of high energy in the electro-magneto-mechanical mill. The work presents the values of the 57Fe isomer shift and quadruple splitting for the components describing the point defect in the local environment of a Mössbauer nuclide. The concentration of the Fe vacancies and Fe atoms substituting Al (Fe-AS) are determined. The results show that an increase in Al content causes an increase in vacancy and Fe-AS concentration.
651
Authors: Magdalena Jabłońska, Aneta Hanc, Anna Szostak
Abstract: In this work, we employed the Mössbauer spectroscopy in a study of point defect formation in intermetallic phases of the B2 structure from the Fe-Al system as a function of Al concentration. We present the values of the 57Fe isomer shift and quadruple splitting for the components describing the point defect in the local environment of a Mössbauer nuclide. The concentration of the Fe vacancies and Fe atoms substituting Al (Fe-AS) are determined. The results shown that an increase in Al content causes an increase in vacancy and Fe-AS
299
Authors: A. Kellou, Thierry Grosdidier, H. Aourag
Abstract: Atomistic modeling based on Density Functional Theory (DFT) within the framework of the Generalized Gradient Approximation (GGA) is used to show the effects of defects such as vacancy, boron, carbon, nitrogen and oxygen substituting Fe or Al atoms in the B2-FeAl structure. The site preference of each type of defect is determined from a comparison of total energycalculations using a supercell structure, consisting of 16-atoms, within which each the various defects are introduced. The changes in lattice parameter and bulk modulus associated to the presence of the defects in the FeAl matrix are also studied.
87
Authors: Yun Ha Yoo, Jung Gu Kim
Abstract: Aqueous corrosion behaviors of Fe3Al-based iron aluminides were investigated. From the result of cyclic anodic polarization tests conducted in 3.5 wt.% NaCl solution at 25, 48, 72 and 95°C, as the temperature increased, the resistance to pitting corrosion decreased significantly, especially over the range of 25~48°C. From the result of crevice corrosion tests, no crevice corrosion occurred on FAL-Mo in the lower chloride-containing solution (200 ppm Cl-), however, FAL-Mo did not perform as well as the 304L SS in the higher chloride-containing solution (3.5 wt.% NaCl). From the result of anodic polarization tests performed in sulfur-compound solutions, additions of Cr and Mo to the Fe3Al-based iron aluminides tend to improve the aqueous corrosion resistance. Aqueous corrosion behaviors with different Al content evaluated by cyclic anodic polarization test in the chloride-containing solution exhibited the more stable passive behavior and the higher pitting resistance as Al contents increased.
23
Authors: Masafumi Tsunekane, Kyosuke Yoshimi, Kouichi Maruyama
Abstract: In this study, the distribution of colloidal nano-gold particles on the nanoporous surfaces of FeAl single crystals was investigated. Colloidal nano-gold particles were dropped onto the nanoporous surface, and their distribution was observed by TEM. Some of nano-gold particles located at the edges of nanopores. A few additional attempts to improve the wettability of the surfaces were made using surface treatments. As a result, the frequency of nano-gold particles put into nanopores was achieved up to 98.3%.
185
Authors: Stuart R.J. Saunders, D.D. Gohil, Jim P. Banks, M.U. Sheriff, P.F. Tortorelli, J.H. De Van, Ian G. Wright
583
Authors: Ferdinand Dobeš
Abstract: High-temperature creep of a Fe3Al-type iron aluminide alloyed by niobium and different additions of carbon was studied in the temperature range from 600 to 800 °C. The alloys contained (atomic %) (i) 27.6 Al, 1.15 Nb, 0.19 C and (ii) 27.1 Al, 1.11Nb, 0.76 C (Fe balance). Creep tests were performed in compression at constant load with stepwise loading. Stress exponent and activation energy of the creep rate were determined. Creep resistance of the low-carbon alloy is better at lower temperatures, while the opposite is true at temperature of 800 °C.
443
Authors: Pavel Novák, Jan Šerák, Dalibor Vojtěch, Michala Zelinková, Lucie Mejzlíková, Alena Michalcová
Abstract: Pressureless reactive sintering production of iron aluminides is always connected with high porosity of the product. Previous research showed that silicon reduces the porosity significantly. In this work, the effect of alloying elements (Cu, Ni) on the reactive sintering behaviour and on the porosity of Fe-Al and Fe-Al-Si alloys was studied. Microstructure, phase composition, mechanical and tribological properties were studied as functions of alloy composition.
407
Authors: Hiroyuki Y. Yasuda, T. Kase, S. Minamiguchi, A. Yokoyama, Yukichi Umakoshi, P.M. Bronsveld, Jeff T.M. de Hosson
Abstract: The pseudoelastic behavior of Fe3Al single crystals doped with an extra element (e.g. Ti, V, Cr, Mn, Co, Ni, Si, Ga, Ge) was investigated. In binary Fe-23.0at.%Al crystals with the D03 structure, 1/4[111] superpartial dislocations moved independently dragging the nearest-neighbor anti-phase boundaries (NNAPB) during loading. During unloading, the NNAPB pulled back the superpartials decreasing its energy resulting in a giant pseudoelasticity of which the recoverable strain is about 5 %. Addition of a third element significantly affected the pseudoelastic behavior of Fe3Al single crystals. Mn- or Ga-doped crystal demonstrated a giant pseudoelasticity. In particular, Ga-doping was found to be effective in the enhancement of the pseudoelasticity. On the other hand, the amount of strain recovery decreased upon doping of the other elements. The frictional stress of the superpartials, the back stress of the NNAPB and ordered domain structure in the crystals changed upon doping, which was closely related to the pseudoelastic behavior.
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