Solids show the feature of internal friction and the feature of fatigue. As a cause for the both features we assume the migration of atomic items. The driving forces for the migration of the atomic items can be mechanical stress gradients and temperature gradients. In an earlier publication formulas have been derived for the internal friction and for the fatigue. From these formulas follows a relation between internal friction and fatigue. The mechanical stress gradients are the cause of the background of internal friction which shows a monotonous rise with temperature. Temperature gradients in the solid can be produced by total internal friction. In contrast to the background of internal friction the temperature dependence of the total internal friction shows maxima and minima. Because of the relations between internal friction and fatigue the temperature dependence of fatigue shows that the fatigue is caused by temperature gradients. The relation between internal friction and fatigue also shows the influence of the internal friction on the fatigue curve.

By a theoretical consideration of a viscous body it has been deduced a formula for the description of the fatigue properties of ductile metals and plastic materials. This formula has been compared with experimental fatigue data of Wöhler-curves (S-N curves). For cellulose acetate, iron, copper, nickel, silver, zinc and, to a restricted degree, also for aluminum a sufficient accordance between the experimental data and the theoretical curves has been reached. With this procedure it is possible to determine fatigue limits for these materials. Similar results are obtained for the creep of brass. It is supposed that the cause of the fatigue limit is the near surface stress of the specimen.

The method of measurement of the field effect on silicon has been improved. The improvement consists in producing the contact between bulk andinversion layer, which are separated by a depletion layer of high resistance, by means of a high frequency current for which the reactance of the capacity between bulk and inversion layer is low.Es wurde das Verfahren, mit dem der Feldeffekt a n Silizium gemessen wird, verbessert. Die Verbesserung besteht darin, da13 zur Herstellung des Kontaktes zwischen dem Volumen und der Inversionsschicht, die durch die hochohmige Verarmungsschicht getrennt sind, ein hochfreqnenter Probenstrom verwendet wird, fur den der Scheinleitwert der Kapazitat zwischen Volumen und Inversionsschicht groB ist.

From the energy band approximation of KRONIG and PENNEY and TAMXI'S model of surface states a contribution of the electrons localized at the surface to the surface tension of a solid has been deduced. The results illustrate the difference between the surface tension and the surface energy in the case of a solid. It has been explained how the above riientioncd contribution to the surface tension is connected with the existence of a surplus surface-ncar lokal stress.Ausgehend von der Energieband-Nalierung von KRONIG und PENNY und dem Model1 der OberflachenzustBnde von T A n m wurde ein Beitrag der Elektronen, die an der Oberfltlclic lokalisiert sind, zur Oberfliichenspannung von Festkiirpern gefolgert. Die Ergebnisse illustrieren den Unterschied zwischen 0 berfliichenspannung und 0 berfllclienenergie bei Festkiirpern. Es wird gezeigt, wie der genannte Beitrag zur Oberfliichenspannung rnit der Existenz einer rialie der OberflBche lokalisierten Spannung verknupft ist.

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