Influence of Ag-content on the deformation behavior of CuAg cast alloys during high-pressure torsion

Abstract The impact of the Ag-content in CuAg cast alloys on the refinement process and hardening behavior during high pressure torsion was investigated and compared with existing results on powder-based alloys. For that CuAg cast alloys with Ag-contents varying between 3 and 60 at% were under investigation. Depending on the initial volume fraction and phase configuration, the structural and hardness evolution is characterized by a different hardening behavior. The 3 at% and 6 at% Ag alloys possess a bimodal Ag-precipitate distribution that controls the hardness response and causes a two-stage hardening plateau due to the refinement and dissolution of the individual Ag-precipitate fractions at different deformation stages. The final structure obtained after the highest applied strains consists of a single-phase supersaturated structure. In contrast, the alloys with higher Ag-contents, namely 20 at% and 60 at% Ag, exhibit pronounced shear banding in the intermediate deformation range and a continuous hardening. The final structure contains an inhomogenous triplex structure of shear bands along with the Ag and Cu phase. The comparison with powder-based alloys of similar composition indicates a comparable final structure in terms of the ability for full supersaturation but differences in the hardness evolution. The maximum attainable hardness depends on the initial materials exhibiting higher hardness values for the powder-based material which can be linked to the natural oxide layer of the powder particles.