Dislocation-induced acoustic nonlinearity parameter in crystalline solids

Abstract

Based on an orientation-dependent dislocation line energy, a solution to the acoustic nonlinearity parameter is obtained for pure and mixed dislocations in anisotropic crystals. The solution is validated by comparison with molecular dynamic simulations. Parametric studies using this new solution show that (i) elastic anisotropy can significantly change the nonlinear behavior of dislocations including “corners” in the bowed dislocation line, much reduced critical stress for instability, sharp peaks in the β versus applied shear relationship, etc., (ii) mixed dislocations may have distinct behavior that is not bounded by the pure edge and screw dislocations, (iii) asymptotic solutions of the acoustic nonlinearity parameter in terms of power series (as high as 5th order) may not be valid even for pure dislocations in isotropic solids.