Precipitate-induced plastic anisotropy: Explicit solutions of the plastic anisotropy due to plate-shaped precipitates

In some aluminum alloys, the observed plastic anisotropy cannot be explaine d solely by the measured Taylor factor variation. Qualitatively, it has bee n suggested that this difference results from a secondary effect due to pla te-shaped precipitates. Models addressing the effect of plastically-deformi ng and elastically-deforming precipitates have been previously proposed. In the present article, explicit solutions of the anisotropic strengthening i ncrement are presented for the case of plate-shaped precipitates. These sol utions allow a quantitative consideration of the effect of precipitates on different habit planes and of the effect due to stress aging. Generally, in fee materials, precipitates on {100} habit planes are predicted to minimiz e the anisotropy due to texture; precipitates on {111} habit planes are pre dicted to accentuate the anisotropy due to texture; and precipitates on oth er habit planes are predicted to produce a minor effect resulting from an a veraging over a greater number of crystallographically equivalent habit pla nes. Stress aging to alter the relative orientation distribution of a singl e precipitate type is predicted to produce only slight changes in the plast ic anisotropy. Larger effects on the yield variation will be observed when stress aging alters the relative volume fractions of two precipitate types on different habit planes.