Microstructure and properties of nanostructured Cu28 wt%Ag microcomposite deformed after solidifying under a high magnetic field

Abstract

Abstract We have studied the effect of an external high magnetic field (HMF) on the solidified microstructure of Cu28 wt%Ag alloys, and we have modeled the impact of microstructural parameters on both the mechanical strength and the electrical resistivity of CuAg microcomposites. Subjecting CuAg alloys to an external HMF during solidification resulted in microstructural changes. In microscale, suppression of convection by HMF increased respectively the solubility of Ag in proeutectic Cu by 41% and the dendrite arm spacing throughout the alloy by 18%. In nanoscale, however, HMF decreased the spacing of nano-sized Ag precipitations in proeutectic Cu and increased rod-like Ag precipitates. HMF resulted in an increase in the growth velocity of Ag precipitates. This caused changes in Ag morphology and concentration, thus enhancing local microhardness in proeutectic Cu regions. After introduction of heavy deformation in solidified Cu28%Ag alloys, we observed that the microstructure of these microcomposites remained coarser in the presence of HMF than in its absence. The application of HMF increased electrical resistivity at 293 K and 77 K, but reduced hardness and ultimate tensile strength. Our model demonstrated that Ag precipitate in proeutectic Cu impacts significantly to both mechanical strength and electrical conductivity.