Diffusion in Materials

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Authors: Kseniia Kovaleva, Anastasiia Karpushkina, Gleb Litvinenko, Tatiana Popova, Alexey O. Rodin
Abstract: The Ga penetration process along grain boundaries of Al-based alloys while they are in contact with Ga containing aqueous solution was studied. It was shown that exposure in the solution at room temperature leads to the liquid Ga penetration process, which started with 3 minutes delay. The penetration rate for Al-4.7 % Zn (13 μm/s) is two times less than penetration rate in pure Al. As for Al-Cu alloys it was shown that penetration process occurs only for the alloys with 1.6 % Cu and less, but for larger value of Cu concentration Ga did not penetrate in Al. Comparison of the effect with pure Ga spreading over the alloys surface showed that the absence of penetration connected with absence of wetting.
Authors: Dan Dan Liu, Jochen Fiebig, Martin Peterlechner, Simon Trubel, Matthias Wegner, Yong Du, Zhan Peng Jin, Gerhard Wilde, S. Divinsky
Abstract: The radiotracer technique was used to measure the grain boundary diffusion of 44Ti and 63Ni in slightly Ni-rich polycrystalline NiTi compound in the temperature range of 673 - 923 K. The temperature dependence of the grain boundary triple product P (P = sδDgb, s is the segregation coefficient, δ is the grain boundary width, and Dgb is the grain boundary diffusion coefficient) for Ti and Ni was determined. The triple products of both Ti and Ni grain boundary diffusion in NiTi reveal a unique behavior with significant deviations from an Arrhenius-type dependence. Probable evolution of the grain boundary structure with temperature was used to interpret this phenomenon.
Authors: Alexander Petelin, Andrey Plokhikh, Alexander Novikov, Elena Novikova
Abstract: The results of metallographic studies show the effect of the layers thickness of multilayer metal material on the diffusion depth after chemical heat treatment. The accelerate diffusion model of diffusible element along layers boundaries is proposed.
Authors: Takahiro Kinoshita, Takashi Kawakami, Katsuyuki Kawamura, Tsutomo Mashimo
Abstract: Molecular dynamics (MD) simulations were performed to investigate unique crystalline states of typical ionic crystal at condition of a strong gravitational field (one million G). The simulation results showed that lattice vibration spectra of anion and cation along the gravity direction were different from the spectra along normal directions of the gravity. It is also shown that the shapes of spectra along the gravity are obviously different from the others along normal directions of the gravity. In addition, the peaks of spectra along the gravity were shifted. The simulation results showed that anisotropic lattice vibration spectra were induced by strong gravitational field, and it is insisted that the unique crystalline states and physical properties are induced by strong gravitational field.
Authors: Yoichi Okamoto, Masami Aono, Hisashi Miyazaki, Yudai Ogata, Makoto Tokuda, Tamotsu Mashimo
Abstract: There were still unclear questions in the new method that fabricate the high quality poly crystalline Si thin film from amorphous Si thin film with lower annealing temperature than conventional Si recrystallization temperature. In that recrystallization process, the recrystallization mechanism was generally explained by the MIC (Metal Induced Crystallization) of Au. In this paper, we have discussed the effects of film structure and strong gravity on recrystallization, by using conventional furnace and high-temperature ultracentrifuge furnace system. The five kinds of samples (two bilayered Si/Au thin films, two multilayered Si/Au thin films and trilayered Si/Au/Si thin film) and found the effects of structure and strong gravity. The best for crystallization was Au/Si multilayered thin film, which is almost finished to crystallize even at 673 K annealing. The strong gravity advanced and retreated the crystallization, depending to thin film structure.
Authors: Jahirul Islam Khandaker, Makoto Tokuda, Yudai Ogata, Tadao Nishiyama, Tsutomo Mashimo
Abstract: Strong gravitational field induces sedimentation of atoms due to the different body forces acting on respective atoms, and gives a tool for controlling elemental compositions in condensed matter. Vanadium oxide (V-O system) has large contrast in phases like VO, V2O3, VO2, V2O5 etc., and shows the respective interesting diverse electrical and optical properties. We performed a strong-gravity experiment (0.397106G at 400°C for 24 hours) on a V2O5 polycrystal using the high temperature ultracentrifuge to examine the composition change and further the structure change. It was found by the XRD and Raman scattering method that VO2 and V2O3 phases appeared and the amounts were increased, while one of the V2O5 phase decreased gradually along with the increasing gravitational field.
Authors: A. Filatov, A. Pogorelov, D. Kropachev, O. Dmitrichenko
Abstract: The influence of moving dislocations on mass-transfer and the phenomena, accompanying it in pulse-deformed metals is studied in a real-time. Transport of self-interstitial atoms (SIAs) by mobile edge dislocations in crystal with FCC lattice is investigated by molecular dynamics. A strain rate (106 s-1) and dislocation density (1010 – 1012 cm-2) in simulated crystal corresponds to a laser effect in a Q-factor mode. The experimental investigations in a real-time are performed by recording of electrical signal induced by the laser pulse irradiation of metal foils of different crystal structures.
Authors: Victor Lacaille, Guillaume Kermouche, David Yezid Tumbajoy-Spinel, Eric Feulvarch, Constance Morel, Jean Michel Bergheau
Abstract: It is well known that nanocrystalline materials have enhanced diffusion properties due to their high grain boundary density which act as fast diffusion channels compared to the lattice. In this paper, we aim at simulating the nitriding process of a pure iron nanostructured by NanoPeening® process. We use a simple diffusional approach taking into account the grain size and the grain morphology resulting from the NanoPeening® treatment. EBSD measurements are carried out to extract morphological parameters which are used in the homogenization method to extract the effective diffusivity distribution. Then a 1D diffusion simulation is performed with this distribution and shows that the grain morphology resulting from the NanoPeening® treatment does not deteriorate the diffusion properties of the material but in fact, improves the nitrogen penetration depth and the diffusion kinetics in addition to the effect of the grain size reduction.
Authors: J.V. Osinskaya, A.V. Pokoev
Abstract: The paper presents a brief review of experimental results obtained in the study on the effect exerted by Ni-additives (0.4 and 1.0 wt. %) on the kinetic processes occurring during the artificial aging of copper-beryllium alloys under a constant magnetic field. Probable atomic mechanisms of the effects observed are also discussed.
Authors: A.V. Pokoev, A.A. Fedotov
Abstract: A brief review of experimental data on the effect exerted by both constant and pulse magnetic field upon the heterodiffusion in powders, polycrystalline and monocrystalline ferromagnetic metals and alloys is presented in the paper in order to analyze regularities and mechanisms of the initiation of numerous phenomena covered by the single term “magneto-diffusion effect”. The most probable mechanisms of the magnetic field influence on the diffusion processes are analyzed.

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