Influence of solidification conditions, thermomechanical processing, and alloying additions on the structure and properties of in situ composite Cu-Ag alloy

Abstract

There is considerable interest in the development of high strength Cu-base composites with high conductivity for applications such as high field magnets 1, 2, 3, 4, 5, 6 and 7, and essentially two alloy types have been examined, where a phase distributed in the Cu matrix during solidification is transformed into fine filaments during cold working of the material to sheet or wire 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20. Some of these are Cu-Ag alloys 8, 9, 10, 11, 12, 13 and 14, with the Ag present as inter-cellular or inter-dendritic phase, or as part of a Cu-Ag eutectic. The other alloys are of the Cu-bcc element type 15, 16, 17, 18, 19 and 20, where the bcc element (Cr, Fe, Nb, etc.) is present as primary dendrites after solidification. For Cu-Ag alloys, it has been shown that the second phase Ag is transformed into fine filaments or rods during working, and it is the reduction of the distance between such matrix-Ag interfaces that is responsible for the increased hardening 8, 12 and 14.