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On the melt line slope of alloys
Solid State Communications, Vol. 19, pp. v - x i , 1976.
Pergamon Press.
Printed in Great Britain
Abstracts of Articles to be Published in The Journal of Physics and Chemistry of Solids 'J Phys. Chem. Solids (to be published)' should be cited in references to material quoted from this section prior to the publication of the relevant article.
1.
OPTICAL AND THERMAL PROPERTIES OF F AND F AGGREGATE CENTERS IN KF William C. Collins and Irwin Schneider, Naval Research Laboratory, Washington, D.C. 20375, U.S.A.
A detailed investigation has been carried out of the optical and thermal properties of centers such as F, FA, M, and M A in pure, Na-doped and H-doped KF. Most centers exhibit properties which are qualitatively similar to those produced in other potassium halides with the notable exception of the FA(Na ) center, which has both type I and type II behavior. Received 26 November 1976 2.
For higher concentrations and insufficient annealing of the sample, clusters of hydrogen atoms are formed even in the a-phase, as indicated by the increasing width of the local mode. The peak intensity of the E~n mode decreases upon changing the temperature from 423 to 673°K. Upon changing the direction of the k-vector from the [1, O, 0]- to the [1, 1,0J-direction, the peak intensity of the local mode decreases by a factor of ten. These observations indicate the existence of anharmonic effects along the [1, 1,0J-direction. Received 19 June 1975 Revised 26 February 1976 3.
K.A. Holsapple, University of Washington, Seattle, Washington 98195, U.S.A.
THE MOTIONS OF HYDROGEN IMPURITIES IN a-PALLADIUM-HYDRIDE W. Drexel, A. Murani and D. Tocchetti, Institute Max von Laue-Paul Langevin, Grenoble, France; W. Kley, Joint Research Center, Ispra, Italy; I. Sosnowska, University of Warsaw, Warsaw, Poland; and D.K. Ross, University of Birmingham, Birmingham, England.
ON THE MELT LINE SLOPE OF ALLOYS
An equation is derived that gives the slope in the temperature-pressure plane of the boundaries of the melt region for certain metal alloys. This equation is in terms of the macroscopic thermodynamic properties that can be determined by atmospheric pressure experiments. The equation includes terms that are not present for a pure material. When these terms are omitted, the result reduces to the well-known Clausius-Clapeyron equation. Numerical results are given for the aluminum alloy 2024. The predicted melt slope is 60-70% higher than that for pure aluminum. This example illustrates that it may be important to distinguish between the behavior of pure metals and alloys in studies involving the behavior in the melt region, as, for example, in recent studies of dynamic response at elevated temperatures.
The intensity distribution of inelastically scattered thermal and hot neutrons on hydrogen impurities in a-palladium hydride has been studied as a function of concentration, temperature, momentum transfer and different annealing procedures. In up-scattering experiments the first and second harmonics appear at E ~ = (66 -+ 4)meV and E ~ = (135 + 15) meV respectively, and the hydrogen band modes have a frequency distribution as expected from measured dispersion curves for pure palladium. For deuterium the first harmonic appears at E~ = (48 +- 4) meV. The width of the hydro4. gen local mode E ~ changes from 30 to 20 meV and its position from 63 to 66 meV, when the hydrogen concentration is altered from 2.7 to 0.2 at.%. After an extended annealing procedure and at the lowest concentration of 0.2 at.%, the local mode appears in down-scattering experiments at E ~ = (68.5 -+ 2) meV with a full width at half height A E ~ = 4 meV, which is purely instrumental.
Received 11 March 1975 Revised 20 February 1976 ETUDE PAR CORRELATION ANGULAIRE 7~1' PERTURBEE DES ASPECTS STATIQUES ET DYNAMIQUES DE LA STRUCTURE DU HEPTAFLUOROHAFNIATE DE SODIUM P. Boyer, O. de O. Damasceno, J.D. Fabris, J.R.F. Ferreria, A.L. de Oliveira et J. de
Pergamon Press.
Printed in Great Britain
Abstracts of Articles to be Published in The Journal of Physics and Chemistry of Solids 'J Phys. Chem. Solids (to be published)' should be cited in references to material quoted from this section prior to the publication of the relevant article.
1.
OPTICAL AND THERMAL PROPERTIES OF F AND F AGGREGATE CENTERS IN KF William C. Collins and Irwin Schneider, Naval Research Laboratory, Washington, D.C. 20375, U.S.A.
A detailed investigation has been carried out of the optical and thermal properties of centers such as F, FA, M, and M A in pure, Na-doped and H-doped KF. Most centers exhibit properties which are qualitatively similar to those produced in other potassium halides with the notable exception of the FA(Na ) center, which has both type I and type II behavior. Received 26 November 1976 2.
For higher concentrations and insufficient annealing of the sample, clusters of hydrogen atoms are formed even in the a-phase, as indicated by the increasing width of the local mode. The peak intensity of the E~n mode decreases upon changing the temperature from 423 to 673°K. Upon changing the direction of the k-vector from the [1, O, 0]- to the [1, 1,0J-direction, the peak intensity of the local mode decreases by a factor of ten. These observations indicate the existence of anharmonic effects along the [1, 1,0J-direction. Received 19 June 1975 Revised 26 February 1976 3.
K.A. Holsapple, University of Washington, Seattle, Washington 98195, U.S.A.
THE MOTIONS OF HYDROGEN IMPURITIES IN a-PALLADIUM-HYDRIDE W. Drexel, A. Murani and D. Tocchetti, Institute Max von Laue-Paul Langevin, Grenoble, France; W. Kley, Joint Research Center, Ispra, Italy; I. Sosnowska, University of Warsaw, Warsaw, Poland; and D.K. Ross, University of Birmingham, Birmingham, England.
ON THE MELT LINE SLOPE OF ALLOYS
An equation is derived that gives the slope in the temperature-pressure plane of the boundaries of the melt region for certain metal alloys. This equation is in terms of the macroscopic thermodynamic properties that can be determined by atmospheric pressure experiments. The equation includes terms that are not present for a pure material. When these terms are omitted, the result reduces to the well-known Clausius-Clapeyron equation. Numerical results are given for the aluminum alloy 2024. The predicted melt slope is 60-70% higher than that for pure aluminum. This example illustrates that it may be important to distinguish between the behavior of pure metals and alloys in studies involving the behavior in the melt region, as, for example, in recent studies of dynamic response at elevated temperatures.
The intensity distribution of inelastically scattered thermal and hot neutrons on hydrogen impurities in a-palladium hydride has been studied as a function of concentration, temperature, momentum transfer and different annealing procedures. In up-scattering experiments the first and second harmonics appear at E ~ = (66 -+ 4)meV and E ~ = (135 + 15) meV respectively, and the hydrogen band modes have a frequency distribution as expected from measured dispersion curves for pure palladium. For deuterium the first harmonic appears at E~ = (48 +- 4) meV. The width of the hydro4. gen local mode E ~ changes from 30 to 20 meV and its position from 63 to 66 meV, when the hydrogen concentration is altered from 2.7 to 0.2 at.%. After an extended annealing procedure and at the lowest concentration of 0.2 at.%, the local mode appears in down-scattering experiments at E ~ = (68.5 -+ 2) meV with a full width at half height A E ~ = 4 meV, which is purely instrumental.
Received 11 March 1975 Revised 20 February 1976 ETUDE PAR CORRELATION ANGULAIRE 7~1' PERTURBEE DES ASPECTS STATIQUES ET DYNAMIQUES DE LA STRUCTURE DU HEPTAFLUOROHAFNIATE DE SODIUM P. Boyer, O. de O. Damasceno, J.D. Fabris, J.R.F. Ferreria, A.L. de Oliveira et J. de