Enhanced strength-ductility synergy in an ultra-strong copper alloy via coherent nanoprecipitates and stress-induced twinning

Deformation twins (DTs) and stacking faults (SFs) are rarely found in Cu-20Ni-20Mn alloy, which limits further strengthening of alloy. Here, we report ultra-strong Cu-20Ni-20Mn alloy prepared by introducing a high density of coherent nanoprecipitates. The ultimate tensile strength (UTS) of alloy can be largely enhanced to 1624.7 +/- 14.7 MPa, while maintaining an acceptable elongation of 7.3 +/- 0.5%. We find that the coherent nanoprecipitates contribute to an ultra-high true stress up to about 1740 MPa, which facilitate the formation of DTs. The strength and ductility improvement stems from the synergistic effect of dislocations, nanoprecipitates and DTs.