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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 503-508 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A series of Al-6.27 at. % Mg alloys were thermally evaporated in a vacuum at 1910 K. The length of time during which the alloy was molten and was evaporating was varied from very short times to a length of time sufficient for complete evaporation of the alloy. The thickness and average composition of the deposited films were determined with thin-film x-ray microanalysis in the analytical electron microscope. A solution/flux model was developed to simulate the evaporation process. The model treated the liquid Al-Mg alloy as a regular solution using experimentally determined Raoultian activity coefficients. The evaporative flux was calculated according to the expression of Langmuir. The solution and flux equations were numerically integrated with respect to time to accommodate changes in mass and liquid alloy composition as the molten alloy evaporated. The agreement between the model and the experimental data (evaporation rate, rate of composition change in the molten alloy, film thickening rate, and average film composition) was excellent. The experimental data and the results of the solution/flux model show that the Mg is evaporated from the melt very quickly. The time required for Mg depletion is approximately 3% of the time required for total evaporation of the alloy. The solution/flux model calculates an average activation energy for evaporation of 72 400±4000 cal/mol over the temperature range 1800–2400 K, which is in good agreement with the thermodynamic enthalpy change for vaporization of 72 300±2000 cal/mol at 2110 K.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 3425-3429 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Interdiffusion in the Ta-W system, a continuous body-centered-cubic solid solution, has been investigated in the temperature range 1300–2100 °C with single-phase diffusion couples prepared by chemical vapor deposition. Fine inclusions, presumably oxides or carbides, decorated the couple interfaces and served as Kirkendall markers. The diffusion annealing times ranged from 16 h to 220 days. The resulting concentration profiles were measured with the electron microprobe and analytical electron microscope. The chemical diffusion coefficient was determined by the classical Boltzmann–Matano technique. The intrinsic diffusivities were determined by the technique of Darken. In the composition range 20–80 at. % W, the activation energy Q for chemical diffusion was constant at 130.5±1.5 kcal/mole. The activation energies for the intrinsic diffusion coefficients at the composition of the Kirkendall marker plane, approximately 70 at. % W, were Q(Ta)=132.3±0.5 kcal/mole and Q(W)=122.0±0.5 kcal/mole.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The journal of supercomputing 6 (1992), S. 139-151 
    ISSN: 1573-0484
    Keywords: Monte Carlo ; parallel ; electron ; microscopy ; random number generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A parallel implementation of a Monte Carlo algorithm for modeling the scattering of electrons in solids and the resulting X-ray production is described. Two important issues for accurate and fast parallel simulation are discussed-random number generation and load-balancing. Timing results for the parallel simulation are given which show even modest-sized parallel machines can be competitive with conventional vector supercomputers for Monte Carlo trajectory simulations. Examples of parallel calculations performed to analyze specimen composition data and to characterize electron microscope performance are briefly highlighted.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 5 (1986), S. 299-302 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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