Evolution of voids close to an inclusion in hot deformation of metals

Void formation and evolution around an inclusion in an elastic–viscoplastic matrix under condition of compressive deformation have been simulated using finite element method. A cell model that includes matrix and inclusion was employed. Two kinds of loading conditions, i.e., displacement-controlled loading and stress-controlled loading, were applied to outer boundary of the cell model. Evolution of voids goes through a sequence of shapes from convex with two cusps, and finally to concave with three cusps together with self-welding lines. Along the matrix–inclusion interface three zones were proposed to characterize the interfacial relative motion and deformation feature near the interface, which are separating, sliding and sticking zones. The large relative sliding between the inclusion and the matrix is the most distinguished feature in the compressive deformation of material with cylindrical inclusions. The size of voids is strongly affected by temperature as the strain increases. The profile of voids predicted is in good agreement with that from the existing experimental observation.