Abstract
A quantitative estimate is made of the increase Δτ0 of the critical resolved shear stress for the case of solid solutions containing spherical and coherent precipitates. The interaction between edge dislocations and the coherency strain fields is believed to be the strengthening mechanism. The calculation is applied to experimental measurements on Al‐Zn and CuCo alloys. For small particles (R/b < 20) the dislocations tend to cut through the precipitates, whereas for larger particles the Orowan mechanism becomes predominant.