Suppression of discontinuous precipitation and strength improvement by Sc doping in Cu-6 wt%Ag alloys

Achieving High Strength and High Conductivity of Cu-6 wt%Ag Sheets by Controlling the Aging Cooling Rate

“…In Cu-Ag alloys with low Ag content, there are mainly large-angle grain boundaries, so Ag often forms discontinuous precipitated phases after aging treatment and it is difficult to obtain a large number of continuous precipitated phases [ 34 , 35 ]. The researchers found that the addition of Zr, Sc, and other elements can significantly inhibit the discontinuous precipitated phase and increase the continuous precipitated phase [ 16 , 19 ]. However, the addition of a third element significantly reduced the electrical conductivity of the alloy despite its high strength.…”

“…At present, most water-cooled magnets above 30 T are made of Cu-Ag alloy sheets [ 8 , 9 , 10 ]. Since Ag is expensive, low Ag content (<8 wt.%) Cu-Ag alloys have been widely studied to reduce the cost [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Zhang et al [ 18 ] prepared a Cu-5Ag alloy sheet with a strength of 870 MPa and an electrical conductivity of 78% IACS by obtaining a deformation nanotwin structure at liquid nitrogen temperature.…”

“…Gaganov et al increased the tensile strength from 1220 MPa to 1360 MPa by adding the Zr element into Cu-7Ag alloy, but the conductivity of the alloy was significantly reduced from 68% IACS to 58% IACS [ 19 ]. An et al [ 16 ] added the Sc element into Cu-6 wt%Ag alloy and the alloy strength increased to 1080 MPa but the conductivity decreased from 77% IACS to 66% IACS. Although researchers have made some breakthroughs by regulating the microstructure of Cu-Ag alloys, low Ag content Cu-Ag alloy sheets with high strength and high conductivity fabricated by simple processing methods have not been realized so far.…”

“…In Cu-Ag alloys with low Ag content, there is almost no continuous precipitated phase, only a discontinuous precipitated phase exists at the grain boundary. Compared with the discontinuous precipitated phase, the continuous precipitated phase generated by aging treatment can lead the alloy to high conductivity and higher strength [ 11 , 16 , 19 , 23 , 26 ]. Therefore, the regulation of the precipitated phase in Cu-Ag alloy (inhibition of discontinuous precipitated phase, promotion of continuous precipitated phase) is the key factor in achieving high strength and high conductivity in Cu-Ag alloy with low Ag content.…”