Accession Number : AD0658874

Title :   DYNAMICAL BEHAVIOR OF DISLOCATIONS,

Corporate Author : ILLINOIS UNIV URBANA

Personal Author(s) : Gilman,John J.

Report Date : SEP 1967

Pagination or Media Count : 41

Abstract : Direct and indirect measurements of dislocation mobilities are reviewed. It is pointed out that no single functional relation between dislocation velocity and stress exists. Four limiting cases are classified schematically: (a) pure metals and salts (b) covalent crystals and impure others; each at low and high stress levels. For cases (a) and (b) at low stress levels linear viscosity is observed. It is pointed out that a previous treatment of the viscous drag by Mason neglects the dominant role of glide plane sliding and a new treatment is presented. For case (b) at high stress levels (low temperatures) flow is stress-activated and a model based on quantum-tunneling is presented and shown to compare favorably with experiments. The behavior of heterogeneous crystals is discussed. A model proposed by Copley and Kear that predicts dynamic anisotropy is reviewed. (Author)

Descriptors :   (*DISLOCATIONS, DYNAMICS), MOBILITY, MEASUREMENT, STRESSES, ANISOTROPY, VELOCITY

Subject Categories : Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE