Planar defect dominated ultra-high strength Cu-Sn-Ni alloy wires with single FCC structure prepared by cold drawing

Abstract

Nickel bronze is provided with excellent wear and high strength, and it is widely applied to aerospace, electronics, machinery manufacturing, and communications. In this study, Cu-12Sn-2Ni alloy wires were facilitated by cold-drawn without intermediate annealing to a tensile strength of 1.3 GPa and a Vickers hardness of 425 HV. During the drawing process, the grains in Cu-12Sn-2Ni alloy are rapidly refined into nano fibers as a result of the interaction between prevailing plane defects, such as stacking faults and nano twins. Dense deformation twins are generated in the wires due to the alloy's low stacking fault energy of 18 mJ/m². When the strain reaches 3.22, the stacking fault probability and dislocation density increase to 7.6 % and 1.88 × 10¹⁵ m⁻², respectively. Dislocation strengthening and boundary strengthening are calculated to be 468.60 MPa and 781.40 MPa in the wire at the strain of 3.22. The fibrous grain boundaries are derived from a considerable proportion of twining indicating that the strength increment by planar defects such as SFs and twin boundaries occupies the crucial position on the Cu-Sn-Ni alloy. The investigation of the strengthening mechanism of the presented Cu-12Sn-2Ni alloy offers further guidance and understanding for ultra-high strength structural metals.