Synergetic effects in the superposition of strengthening mechanisms

Abstract

If in a ductile material two or more different types of obstacles simultaneously impede the glide of dislocations, the question arises how the individual contributions τ ci superimpose to the total actually observed critical resolved shear stress (CRSS) τ ct · τ ci is the CRSS of specimens strengthened only by type No. i obstacles. Often cross-terms between the different hardening mechanisms lead to strong synergetic effects, which forbid the formulation of simple superposition rules of the form τ ct ( τ ci ). In the present paper three combinations of double strengthening are analyzed: precipitates plus solute atoms, precipitates plus phonons, grain boundaries plus precipitates. The resulting synergisms are discussed.