Elastic anisotropy and the substitutional bainite formation in copper base alloys

The importance of elastic anisotropy in the substitutional bainite (α₁ plate) formation at defects in copper base alloys has been emphasized in this work. It has been argued that a defect such as a dislocation in an elastically anisotropic medium could lower its energy by reducing the energy factor K (elastic anisotropy and thus composition dependent) which in turn would lead to higher elastic anisotropy around the defect through solute reduction. Proof for this is provided through TEM evidence, monitoring the elastic anisotropy dependent bend angles of directionally unstable dislocations in β Cu-Zn-Al as a function of isothermal ageing which eventually leads to bainite formation. The role of elastic anisotropy in promoting both solute diffusion and shear and its implications on the initial stages of bainite formation are discussed.