Ferroelasticity at the Critical Point of Hydrogen in Niobium

Abstract

No abstract availabl

Physical Mechanisms of Intercalation

“…49 Further evidence for this explanation of the transition is found in studies of the an elastic relaxation of the hydrogen (the diffusion of the hydrogen atoms in response to a stress), which show that the diffusion constant depends on the sample shape. 50 Intercalation of hydrogen into palladium shows a similar firstorder transition between two phases, a and a', presumably also due to elastic interactions. 51 (Palladium has a face-centered cubic structure, and hydrogen atoms occupy octahedral sites.)…”

Surface-Directed Spinodal Decomposition on a Macroscopic Scale in a Nitrogen and Carbon Alloyed Steel

“…He modeled spinodal decomposition in a small radially stressed sphere, and obtained a microstructure consisting of a series of concentric layers. Experiments on hydrogen-metal systems by Tretkowski et al [15] studied a very interesting related phenomenon. A spatially varying interstitial concentration caused a varying lattice expansion which led to coherency stresses.…”

Deuterium Diffusion in Niobium: The Influence of Coherency Stresses

“…It is worth point out that Gorsky effect measurements on foil-shaped NbH 0.34 samples [4,6,18] probed macroscopic modes that are not coherency-stress-free. The energy eigenvalue E foil P 2 ͑͞B 1 G͞3͒ (elastic isotropy) [4] of these modes is smaller than E 0 , so that diffusion coefficients obtained from foil-shaped samples are distinctly larger than D chem .…”

“…The elastic energy, which results from coherency stresses, reduces the amplitude of the concentration fluctuations. The elastic energy accelerates further the diffusive decay of these fluctuations and raises, therefore, the value of a collective diffusion coefficient D of the impurity atoms that is defined according to Fick's law:where j is the flux of the impurity atoms, and r is their particle density (number per volume).A prominent model for impurity atoms that cause a lattice expansion, and therefore coherency stresses, is hydrogen (deuterium) interstitials in metals [4][5][6][7][8][9][10][11]. This paper reports on a quasielastic neutron scattering study on a metal-deuterium system, NbD 0.33 , which-together with Gorsky effect results of Bauer et al…”

“…A prominent model for impurity atoms that cause a lattice expansion, and therefore coherency stresses, is hydrogen (deuterium) interstitials in metals [4][5][6][7][8][9][10][11]. This paper reports on a quasielastic neutron scattering study on a metal-deuterium system, NbD 0.33 , which-together with Gorsky effect results of Bauer et al [12]-shows that a diffusion coefficient D, defined according to (1), depends drastically on how coherency stresses accompany the experimentally probed deuterium fluctuation.…”