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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Phase transition and thermodynamic properties of BiFeO3 from first-principles calculations
TL;DR: The phase transition from the trigonal R3c phase to the orthorhombic Pnma phase is a first-order antiferromagnetic-nonmagnetic and insulator-metal transition, and occurs at 10.56 GPa as discussed by the authors.
Journal ArticleDOI
Density functional study of vibrational, thermodynamic and elastic properties of ZrCo and ZrCoX3 (X = H, D and T) compounds
TL;DR: In this article, the dynamical, thermodynamic and elastic properties of ZrCo and its hydrides were investigated using frozen phonon approach, and the results reveal significant difference between the isotopic analogs in terms of phonon frequencies and zero point energies.
Journal ArticleDOI
Phase Transitions and Mechanical Properties of Octahydro-1,3,5,7- tetranitro-1,3,5,7-tetrazocine in Different Crystal Phases by Molecular Dynamics Simulation
TL;DR: In this article, the phase transitions and mechanical properties of the energetic material octahydro-1,3,5,7-tetranitro, 1, 3, 5,7, 7tetrazocine (HMX) in three pure polymorphs crystals, alpha-, beta-, and delta phases, have been studied theoretically isothermal isobaric molecular dynamics simulations were performed in the temperature range of (5 to 555) K at 0 GPa and the pressure range (0 to 40) GPa at 298 K The lattice parameters and volumes
Journal ArticleDOI
Self-interaction corrected LDA + U investigations of BiFeO3 properties: Plane-wave pseudopotential method
Muhamad Kamil Yaakob,Mohamad Fariz Mohamad Taib,Li Lu,Oskar Hasdinor Hassan,Muhd Zu Azhan Yahya +4 more
TL;DR: In this paper, the structural, electronic, elastic, and optical properties of BiFeO3 were investigated using the first-principles calculation based on the local density approximation plus U (LDA + U) method in the frame of plane-wave pseudopotential density functional theory.
Journal ArticleDOI
First-principles studies of typical long-period superstructures Al5Ti3, h-Al2Ti and r-Al2Ti in Al-rich TiAl alloys
TL;DR: In this paper, the structural stabilities, electronic and elastic properties of typical long-period superstructures Al5Ti3, h-Al2Ti and r-Al 2Ti in Al-rich TiAl alloys together with γ-TiAl were investigated.
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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