Journal ArticleDOI
A quantitative demonstration of the grain boundary diffusion mechanism for the oxidation of metals
TLDR
In this article, the authors report measurements of the oxide scale thickness and oxide grain size as a function of time during the oxidation of high-purity nickel in the temperature range 500-800°C.Abstract:
Below 1000°C the oxidation of nickel cannot be controlled by the diffusion of ions through the bulk crystal lattice of the pure oxide, because the measured oxidation rates are several orders of magnitude faster than would be predicted on this basis. Short-circuit diffusion through oxide grain boundaries or dislocations has usually been held responsible, but there has hitherto been no proper quantitative confirmation of this mechanism. We report measurements of the oxide scale thickness and oxide grain size as a function of time during the oxidation of high-purity nickel in the temperature range 500–800°C. All the oxidation experiments were carried out in pure oxygen at a pressure of one atmosphere. The measured parabolic oxidation rate constants have been compared with those calculated from grain boundary diffusion data obtained in our previous work, using a grain boundary diffusion model for the oxidation process. The quantitative agreement between measured and calculated oxidation rates shows c...read more
Citations
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Structural, elastic, electronic, chemical bonding and optical properties of Cu-based oxides ACuO (A = Li, Na, K and Rb): An ab initio study
A. Bouhemadou,O. Boudrifa,N. Guechi,Rabah Khenata,Yarub Al-Douri,Ş. Uğur,B. Ghebouli,S. Bin-Omran +7 more
TL;DR: In this article, the structural, elastic, electronic, chemical bonding and optical properties of Cu-based ternary oxides ACuO (A = Li, Na, K and Rb) were investigated.
Journal ArticleDOI
Investigation of high pressure and temperature study of thermo-physical properties in semiconducting Fe2ZrSi Heusler
TL;DR: In this article, the properties of Fe2ZrSi Heusler along the band structure were examined at high pressure by implementing modified Becke-Johnson (mBJ) scheme.
Journal ArticleDOI
Sulfur embrittlement on γ/γ′ interface of Ni-base single crystal superalloys
K. Chen,L. R. Zhao,John S. Tse +2 more
TL;DR: In this paper, the authors proposed a new method to evaluate the competition between the shear and cohesive strengths of the interface of Ni-base single crystal superalloys using a local sum of vertical (BOv) and horizontal (BOh)Mayer bond orders.
Journal ArticleDOI
New ternary superconducting compound LaRu 2 As 2 : Physical properties from density functional theory calculations
Abstract: In this paper, we have presented the density functional theory (DFT) based calculations performed within the first-principles pseudopotential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elastic constants ensure mechanical stability of the compound. The calculated Cauchy pressure, Pugh's ratio as well as Poisson's ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating (TBC) material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machineable because of its low hardness value of 6.8 Gpa. The multi-band nature is observed in calculated Fermi surface. A highly anisotropic combination of ionic, covalent, and metallic interactions is expected in accordance with charge density calculations.
Journal ArticleDOI
Low effective mass leading to an improved ZT value by 32% for n-type BiCuSeO: a first-principles study
TL;DR: In this article, the authors investigated the thermoelectric properties of BiCuSeO using first-principles calculations and determined that the low electrical conductivity may originate from strong ionic bonding and without a Cu-Se conductive pathway forming near the Fermi level.
References
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Journal ArticleDOI
Beitrag zur Theorie des Anlaufvorgangs
TL;DR: The Mechanismus des Diffusionsvorgangs is still weitgehend unbekannt as discussed by the authors, i.e., the Diffusion of mindestens einem der beiden Bestandteile durch die Anlaufschicht is notwendig.
Journal ArticleDOI
The diffusion of 63Ni along grain boundaries in nickel oxide
A. Atkinson,R. I. Taylor +1 more
TL;DR: The product of the grain boundary diffusion coefficient and width, D′δ, has been measured directly for the diffusion of 63Ni along grain boundaries in high-purity NiO as discussed by the authors.
Journal ArticleDOI
The role of oxide microstructure and growth stresses in the high-temperature scaling of nickel
F. N. Rhines,J. S. Wolf +1 more
TL;DR: In this article, the formation of new nickel oxide upon boundaries of columnar grains where nickel diffusing through the oxide crystals, meets oxygen, diffusing along grain boundaries is identified as the primary cause of this stress.
Journal ArticleDOI
The diffusion of Ni in the bulk and along dislocations in NiO single crystals
A. Atkinson,R. I. Taylor +1 more
TL;DR: In this paper, diffusion profiles of 63Ni tracer in single crystals of NiO following anneals at 522°-1000°C have been determined by a radio-frequency sputter-sectioning technique.
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