Moving Edge Dislocations in Cubic and Hexagonal Materials

Abstract

Numerical values of the threshold and limiting velocities of edge dislocations in various cubic and hexagonal materials are presented; a number of orientations and directions of motion of the edge dislocation are considered. At the limiting velocity $C_{\infty }$, the energy of the dislocation becomes infinite; in many instances it is found that the limiting velocity is less than the corresponding velocity of shear sound. At the threshold (Rayleigh) velocity $C_R$, the shear stress of the moving edge dislocation vanishes on the slip plane. Edge dislocations of like sign moving at velocities between $C_R$ and $C_{\infty }$ attract rather than repel one another. The lower the value of the ratio $\frac{C_R}{C_{\infty }}$, the easier it should be to bring edge dislocations into the anomalous velocity range. Theoretically this ratio has zero as a lower limit; however, no value of $\frac{C_R}{C_{\infty }}$ less than 0.85 was found for those materials and orientations considered.