A model for coherency strengthening of large precipitates

In precipitation strengthening, the lattice misfit between precipitate and matrix produces a strain field around precipitates, which impedes dislocation movement. In this paper, a strengthening model is presented, which delivers the stress increment associated with the strain field around large homogeneous spherical precipitates. In contrast to previous work, this study takes into account that the effective resistance force on the dislocation depends strongly on the relative position of the slip plane to the precipitate center. On ignoring this effect, the maximum shear stress due to the strong and shearing mechanism is generally underestimated. The results are presented in the form of discrete equations based on the evaluation of the resistance force in front of a moving edge or screw dislocation and, alternatively, with a correction factor for conventional strong and shearing equations.