Dislocation mobility in hydrostatically compressed NaCl crystals

Abstract

The effects of the applied stress τ and temperature on the mobility of edge and screw dislocations in NaCl crystals are investigated under high hydrostatic pressure. The critical shear stress of these crystals is obtained to τs = (40 ± 6) g/mm2. Fresh dislocations are put into starting position by striking. A sample is loaded in the pressure chamber according to the scheme for the four‐point kink. The temperature is varied from +20 up to 150 °C. The results show the decrease of the dislocation mobility under pressure. The velocity ratio of edge and screw dislocations is shown to decrease as the pressure increases. The experimental dependences are in good agreement with the given theoretical analysis which suggests the observed effects to be connected with both, the enhancement of the interaction between dislocations and the local barriers under hydrostatic pressure and the increase of their self energies.

Creep of aluminium single crystals under high pressure

“…I n such a case the condition of the appearance of an inflection point on the curve E ( t ) and a change of its form to the siginoidal one is written as follows: 2 = bi(vo -2 0~~) = 0 . It is known that there is a decrease in mobile dislocation velocity under high pressure [9]. The structural investigation results quoted in this paper ( Fig.…”

Defects in Crystals under Pressure

“…Deformations produced by HI' in the ideal crystal are uniform. It means that the equ a1 i t y holds and, hence, the difference of coordinates of two arbitrary points in states v and 1' is related in the following wag: (8) AX, = KLk AX^ .…”

“…We iise analogous definitions for dislocations and disclinations in 1: state. J,et us rearrange expressions under the integral in (46) and (47) using ( 5 ) , ( 8 )…”

“…,(8), and (9) we obtain the relation between the displacenient vector and the tensor of distortions produced by one and the same defect in 11 and 2' states, Let us introduce the tensor of sniall rotations COtk = f ( 1 l , k -U k , ) .…”