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

Copper single crystals have been simultaneously strengthened by solved gold-atoms and by incoherent SiO2-particles. The critical resolved shear stress (CRSS) τs of a binary copper–gold solid solution and the CRSS τt of the same solid solution additionally strengthened by SiO2-particles have been measured in the temperature range 90–283 K. From the experimentally established temperature dependences of τs and τt and from the theoretically known one of τp (=CRSS if the SiO2-particles are the only strengtheners present), the function τt(τs,τp) has been derived: τt=(τks+τkp)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.