High-Strength, High Conductivity Bulk Nanostructured Ag-Cu Alloys

Researchers are interested in developing high-strength and high conductivity alloys for use in high-field pulsed electromagnets. We have used a fluxing and quenching technique to prepare 5-mm diameter rods of Ag-Cu alloys with nanosized microstructure. Fluxing removes heterogeneous nucleation centers, enabling a higher degree of undercooling. The purified melt is quenched at rates of approximately 100 K/s. The as-quenched alloys are a mixture of metastable Ag-6 at.% Cu and Cu-3.5 at.% Ag solid-solutions and have a eutectic microstructure with approximately 50-nm thick Ag(Cu) and Cu(Ag) lamellae. The alloy's room-temperature compressive yield strength is 370 MPa and its electrical conductivity is 78% of the International Annealed Copper Standard (IACS). These results are evaluated in terms of current understanding on solidification and mechanical properties.