STRENGTHENING EFFECT OF UNSHEARABLE PARTICLES OF FINITE SIZE: A COMPUTER EXPERIMENTAL STUDY

摘要

Equilibrium configurations of a dislocation interacting with randomly distributed unshearable obstacles of finite size under an applied stress are analyzed. Ashby's critical dipole spacing Q' argument for the self stress effect of dislocations is utilized but analysis suggests that the spacing Q' varies with the local obstacle distribution as well as with the obstacle shape. Computer simulations of a dislocation slip process through circular or linear obstacles, that are extensions of earlier work by Forman et al., were conducted. The dependence of the strengthening stress on the obstacle size was found to be less than that predicted by equations currently in use, particularly for linear obstacles. New, modified Orowan equations are suggested for the strengthening effects due to spherical, rod-like, and plate-like obstacles. The effect of the orientation distribution of the linear obstacles demonstrated in the simulation is in agreement with recent experimental observations.