Strengthening of Ods Silver Wires

Abstract

The present work is part of an experimental programme in which the mechanical behavior and the evolution of microstructure and texture of oxide-dispersion strengthened (ODS) silver alloys upon different processing steps like hot-extrusion, cold-working and further annealing have been investigated. In a recent paper the authors investigated the influence of oxide particles on the evolution of microstructure and texture of hot-extruded ODS silver alloys. A main result of these investigations was that the microstructures and textures observed are due to recrystallization and grain growth during or immediately after the hot-extrusion process and that the yield strengths of the composites strongly depend on their microstructure. It is the aim of the present paper to study the influence of oxide particles on the mechanical behavior and the evolution of microstructure and texture of the ODS alloys upon cold-working in more detail. The investigations reveal that the deformation behavior and the evolution of microstructure and texture strongly depend on the size of the second phase particles. Small particles cause a high strengthening of the material but only a small change of the original microstructure and texture. Increasing the particle size subsequently reduces the strength and changes the original microstructure and texture in a more pronounced way. The observed yield strengths can be explained with a linear superposition of the Orowan bypassing model of particles by dislocations and the grain strengthening model according to Hall-Petch. In addition, our results indicate that annealing twins have a strong impact to the Hall-Petch stress.