Deformation-induced contaminants and thermal stability variations in copper processed by high pressure surface rolling

The microstructure and the spatial distribution of deformation-induced contaminants have been investigated in copper processed by high pressure surface rolling. It is found that the topmost layer and some regions below this layer are contaminated as a result of surface oxidation and interaction with the steel rolls. The contamination is seen in the form of films with increased oxygen and iron content. In addition, steel fragments in the range 0.4 - 3 & mu;m are revealed in the material. Although contaminated regions are characterized by small subgrain sizes and a high stored energy, these regions are found to be more resistant to recrystallization than adjacent noncontaminated regions with coarser subgrains.