The work hardening characteristics of LiF single crystals in compression and tension has been investigated as a function of temperature. It was shown that in temperature range from 200 "C to 600 "C four stages of hardening were observed and the main part of plastic flow proceeds in stage IV. The parabolic hardening was not observed. The flow stresses and hardening rates in all stages in compression are higher than those in tension. As a temperature increase this difference decreases. The hardening rates, stresses which correspond to the beginning of the linear hardening stages and the duration of those stages decrease as a teiiiperature increase. At temperatures above 600 "C the yield drop occured. Taking into account a good agreement between the temperature dependences of the critical resolved shear stress and t 1 1 1 the assumption was made that 7111 corresponds t o resolved shear stress in a secondary glide system. H3yYeHbI MeXaHHYeCKHe CBOfiCTBa MOHOKpHCTaJlJlOB LiF npH CXaTHIl

Durch thermodynamische Analyse der im System InSb‐J, verlaufenden Reaktionen wird festgestellt, daß am Transport von InSb hauptsächlich die Disproportinonierungsreaktion Abeteiligt ist.

The peculiarities of the formation and the development of reorientated bands in crystals are considered. Reorientated bands are investigated experimentally in MgO single crystals under the compression testing. It is shown that the misorientation between the material in the band interior and the surrounding volume can reach some degrees. The data of electron microscopy investigations of dislocation structure of such bands are performed. The disclination model is proposed for the propogation of the reorientated bands. This model permits to explain the laws of the band development, for example, the formation of discrete areas with reoriented crystal lattice ahead the terminated band.

No abstract

The average length of dislocation segments between pinning points is estimated in plastically prestrained MgO crystals from measurements of the internal friction and the Young's modulus defect at 100 kHz. The results coincide satisfactorily with those obtained from in situ straining experiments in the high voltage electron microscope.