Edge-to-edge matching and its applications: Part II. Application to Mg–Al, Mg–Y and Mg–Mn alloys

Abstract

A model for the crystallography and morphology of diffusion-controlled phase transformations – edge-to-edge matching – has been used to predict the orientation relationships (OR) and habit planes of precipitates Mg 17Al 12 in Mg–Al alloy, Mg 24Y 5 in Mg–Y alloy and α-Mn in Mg–Mn alloy. Based on the crystal structures and lattice parameters only, the model predicts that the possible ORs between Mg 17Al 12 and Mg matrix are the near Burgers OR, the Potter OR, the Gjönnes–Östmoe OR and the Crawley OR. In the Mg–Y alloy, the OR between Mg 24Y 5 precipitates and the Mg matrix is predicted to be the Burgers OR only. The model also predicts that there are no reproducible ORs between α-Mn and Mg in the Mg–Mn alloy. Combining the edge-to-edge matching model and W. Zhang’s Δ g approach, the habit plane and side facets of the precipitate for each OR can be determined. All the predicted ORs and the corresponding habit planes in Mg–Al and Mg–Y alloys agree very well with the experimental results.