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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 48 (1961), S. 450-451 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 191 (1966), S. 398-408 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The final results of x-ray diffraction experiments in molten alloys are electron distribution curves. These are used to get a decision between statistical distribution of the atoms of different kinds in the melt, between ordering of the atoms or between segregation. The according equations are deduced and finally a simple graphical method for the evaluation of the results is given. Important fact for the evaluation of molten alloys with a great difference between the atomic numbers of the two components is the number of scattering electrons in the first coordination sphere. With molten alloys which show little difference between the atomic numbers of the components the radius of the first coordination sphere is deciding. Finally it is shown, that the short range order parameter, which until now only was used in regard to the ordering in solid solutions, also can be used to get valuable results of the degree of ordering in molten alloys.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Zusammenfassung Mit Röntgenstrahlen wurden Weitwinkelstreuversuche an sieben Al-Sn-Legierungen mit Sn-Gehalten von 3 bis 30 At.-% durchgeführt. Die Intensitätskurven wurden außerdem erstmals mit einer speziellen Apparatur bis zu sehr kleinen Streuwinkeln vermessen, wobei ein Anstieg der Streuintensitäten zum Primärstrahl hin festzustellen war. Diese Kleinwinkelstreuung deutet auf das Vorliegen von Clustern in diesen Schmelzen. Durch Fouriertransformation wurden aus den Intensitätskurven Elektronenverteilungskurven gewonnen, denen die Fläche unter dem ersten Maximum, d.h. die Atomzahln I in der ersten Koordinationssphäre und der Abstandr I des ersten Maximums vom Ursprung entommen werden kann. Aus den früher publizierten Kleinwinkelmessungen ging hervor, daß in den Schmelzen dieses Systems Cluster mit bis zu 10 Å Durchmesser bestehen, offen blieb damals lediglich die Frage, ob diese Cluster nur aus Sn- oder nur aus Al-Atomen bestehen. In vorliegender Arbeit wird nun mit Hilfe eines an anderer Stelle publizierten Clustermodelles entschieden, daß die Cluster lediglich aus Sn-Atomen bestehen. Dieser Schluß ergibt sich aus der Diskussion vonn I,r I und dem Nahordnungsparameterα, wobei es nötig war, alle drei Größen für verschiedene Atomzahlen in den Teilchen theoretisch zu berechnen und mit dem Experiment zu vergleichen. Dabei zeigte sich, daß mit Hilfe dieser Methoden sehr wohl zwischen den verschiedenen Graden der Entmischung, also von der (atomaren) Nahentmischung bis zur (makroskopischen) Grobentmischung entschieden werden kann. Außerdem ist die Angabe von Nahordnungsparametern nur sinnvoll bei einer gleichzeitigen Aussage über die Teilchengröße. Schließlich sei darauf hingewiesen, daß die hier durchgeführten Betrachtungen nicht nur für Metallschmelzen, sondern auch für feste amorphe Stoffe gelten.
    Notes: Abstract Seven Al-Sn-alloys (3 up to 30 a/o Sn) were investigated by means of X-ray wide angle scattering experiments. Furthermore, the intensity curves were measured at very small scattering angles using a special apparatus. Thereby an increase of scattered intensity towards the primary beam could be observed. This small angle scattering shows the existence of clusters in these melts. By a Fourier-transform from the intensity curves electron distribution curves were obtained, which yielded the area below the first maximum, i.e., the atomic numbern I in the first coordination sphere and the distancer I of the first maximum from the origin. Formerly published results of small angle scattering measurements showed the existence of clusters within these melts with diameters up to 10 Å. At that time the question could not be answered, whether these clusters consist of Sn- or Al-atoms only. During the course of this work it could be decided that the clusters consist of Sn-atoms only. This follows from the discussion ofn I,r I and the short range order parameterα in terms of a so-called cluster model. This method allows to decide between the different kinds of segregation, from macroscopic segregation to microsegregation. The treatment shown in the paper is not only applicable for melts, but also for amorphous solids.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 14 (1972), S. 307-313 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Zusammenfassung Beziehungen für die FlächeF unter dem ersten Maximum von Elektronenverteilungskurven werden für drei verschiedene Modelle von Schmelzen bzw. amorphen Festkörpern abgeleitet. Diese Modelle sind die statistiche Atomverteilung, die makroskopische Entmischung und die Mikroentmischung. Letztere wird durch ein sogenanntes Clustermodell repräsentiert. Dabei haben die Cluster variable Größen bis hin zur Größe der ersten Koordinationssphäre, also etwa 10 Å Durchmesser. Weiterhin werden Beziehungen angegeben zur Bestimmung der Zahl von Streuelektronen in der ersten Koordinationssphäre eines gemittelten Bezugsatoms in diesem Clustermodell und außerdem zur Bestimmung des Cowleyschen Nahordnungsparameters für dieses Modell. Für die drei oben angegebenen Modelle wird zudem noch die Beziehung zur Berechnung der Lager I des ersten Maximums der Streuelektronenverteilungskurven angegeben. Schließlich ist noch auf die wichtige Tatsache hinzuweisen, daß zur vollständigen Interpretation von Kleinwinkelstreuxperimenten an amorphen Festkörpern und Schmelzen unbedingt auch die Ergebnisse der Weitwinkelstreuversuche herangezogen werden müssen.
    Notes: Abstract Equations for calculating the areaF below the first maximum of electron distribution curves are deduced for three models of melts as well as of amorphous solids. These models are the statistical distribution of atoms, the macroscopic segregation and the microsegregation. The latter is represented by a so-called cluster model, in which the clusters have variable diameters (up to the diameter of the first coordination sphere, i.e., about 10 Å). Furthermore, equations valid for the cluster model are given for the determination of the number of scattering electrons in the first coordination sphere of a corresponding mean atom, as well as for the determination of Cowley's short range order parameter. For the three models mentioned above the positionr I of the first maximum of the electron distribution curve can be determined. Finally the important fact is stressed that for the complete interpretation of small angle scattering experiments on amorphous solids and melts it is necessary to discuss the results of wide-angle scattering experiments.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 17 (1973), S. 1-10 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The concentration dependency of sound velocity was measured in molten alloys of the three systems Al−Mg, Al−Sn, and Mg−Sn in the temperature region between liquidus and 1000°C. Furthermore it was measured in molten alloys of the system Fe−C in the temperature range between liquidus temperatureT L andT L+150°C. From the velocities the compressibilities were calculated, whose concentration dependency revealed changes in the structure of the melts. The structure of the three systems Al−Mg, Al−Sn, and Mg−Sn in the molten state was already investigated by X-Ray diffraction. These results were compared with the results of velocity measurements. Inhomogeneities in the melts yield increased values of compressibility compared with the values to be expected for statistical distribution of the atoms. This result was used for the discussion of the structure of molten Fe-C-alloys: The conclusion can be drawn, that within the melts of the system Fe−C above 3w/0 C inhomogeneities are existent. From the values of sound velocity in the molten elements the temperature dependency of the structure factorsI(0) was calculated and compared with experimental values.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 101 (1989), S. 975-977 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 951-953 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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