Double strengthening of copper by dissolved gold-atoms and by incoherent SiO2-particles: how do the two strengthening contributions superimpose?

Abstract Copper single crystals have been simultaneously strengthened by solved gold-atoms and by incoherent SiO 2 -particles. The critical resolved shear stress (CRSS) τ s of a binary copper–gold solid solution and the CRSS τ t of the same solid solution additionally strengthened by SiO 2 -particles have been measured in the temperature range 90–283 K. From the experimentally established temperature dependences of τ s and τ t and from the theoretically known one of τ p (=CRSS if the SiO 2 -particles are the only strengtheners present), the function τ t ( τ s , τ p ) has been derived: τ t =( τ k s + τ k p ) 1/ k , with k ≈1.8. This result is at variance with a linear relationship suggested earlier by Ebeling and Ashby [Phil. Mag. 13 (1966) 805]. The bearings of the present findings on the evaluation of experimental data on dispersion strengthening are evident.