Constriction energy in the presence of a solute field

It has been widely known that both solute concentration, i.e., frictional e ffects, and stacking fault energy influence the degree of cross slip and sl ip planarity in face-centered-cubic alloys. Cross slip is preceded by const riction of two partial dislocations. A model is proposed for the energy req uired to form a constriction from two parallel partial dislocations as a fu nction of stacking fault energy, solute concentration, atomic size misfit, and modulus mismatch. The cross slip is curtailed due to interaction of sol ute atoms with the partials. Both the atomic size misfit and modulus mismat ch influence the local solute concentration which introduce local stresses that determine the energy needed to form the constriction. The shape of par tials and the energy to form the constriction was established for stacking fault energies in the range of 10-100 mJ/m(2), misfit strains in the range of 0.1-0.5, modulus mismatch levels of -1.0, and nominal solute concentrati ons varying from 0 to 10 at. %. In extreme cases, the constriction energy h as been found to increase fourfold compared to the solute-free case. The mo dulus mismatch effect is important in substitutional alloys with small misf it strains (< 0.1) while for interstitial solute cases the misfit strain ef fects dominate. The results converge to the well-known solution of Stroh in the limit of zero solute concentration. (C) 2000 American Institute of Phy sics. [S0021-8979(00)04905-7].