Ultrahigh Strength and High Electrical Conductivity Characteristics of Cu-Zr Alloy Wires with Nanoscale Duplex Fibrous Structure

Abstract

The cold drawing of cast Cu_100−xZr_x (x=3, 4 and 5 at%) alloys to the reduction ratio of 99.7% was found to cause simultaneous achievement of ultrahigh tensile strength of 1350 to 1800 MPa and high electrical conductivity of 30 to 45%IACS (International Annealed Copper Standard). The cold-drawn Cu₉₅Zr₅ alloy wire has a well-developed fibrous structure of fcc-Cu and tetragonal Cu₉Zr₂ phases. The volume ratio of the fcc-Cu phase was evaluated to be about 76%. A very high density of internal defects was observed inside the Cu₉Zr₂ phase in the cold-drawn Cu₉₅Zr₅ alloy. The microstructure data suggest that the Cu fibrous phase with high aspect ratios is the origin for the achievement of high electrical conductivity and the well-developed fibrous structure contributes to the high tensile strength. The success of synthesizing the Cu-Zr alloy wire with simultaneously high tensile strength and high electrical conductivity exceeding the best combination of all Cu-based alloys reported up to data is expected to be used as a new type of high-strength and high conductivity material because of some advantages of energy saving, low materials cost and simple production process.