Deformation-induced dissolution of copper precipitation in 1.5wt%Cu-bearing antibacterial Fe-17wt%Cr alloy during plastic deformation process

Highlights: • The copper precipitation dissolved into the matrix during plastic deformation process. • Severe plastic deformation resulted in deterioration of antimicrobial property. • The matrix solubility increased and the critical radius of the precipitation decreased during cold rolling process. • Two dissolution models were proposed based on the arrangement of copper precipitation. Antibacterial Fe-Cr alloy is emerging in biomaterials. To study the influence of plastic strain on the copper precipitations in this material, a series of experiments were performed in this paper. A commonly used Fe-17wt%Cr alloy with 1.5wt%Cu was cold rolled with a reduction from 12.5% to 75%. It was found that the rod-shaped copper precipitations transformed to acicular or equiaxed and the lattice constant of the matrix became larger after cold rolling which demonstrated that the copper precipitations dissolved into the matrix. The antibacterial tests indicated that the material will lose its antibacterial effectiveness after cold rolling. These phenomena are because that the copper precipitation is softer than the matrix and the plastic deformation more easily occurs in copper precipitation, which significantly improves the gibbs free energy of copper precipitation resulting in a bigger copper solubility and critical precipitation radius. Therefore, the copper precipitation dissolves into the matrix during the cold rolling process and the antibacterial function deteriorates. These results will provide fundamental guidelines for the optimal design of antibacterial Fe-17wt%Cr alloy production process.