Strengthening mechanism of cold-drawn wire of in situ Cu-Cr composite

A heavily deformed Cu-Cr in situ composite is quite promising as a material with high strength and high conductivity. In order to make clear the strengthening mechanism of the Cu-Cr in-situ composite, the Cu-15 mass%Cr composite wire, fabricated by the conventional process from the ingot, was investigated in terms of the variation of microstructure, hardness and tensile strength with increasing drawing strain. The results are summarized as follows. (1) The thickness and spacing of Cr phase decrease exponentially with increasing drawing strain. (2) The hardness and tensile strength increase proportionally with increasing drawing strain. High tensile strength of 906 MPa is attained at a maximum drawing strain of eta=6.87. (3) It is understood that the tensile strength involves the additional component due to the work hardening of the Cu matrix oil the basic component due to microstructural fineness, obeying the Hall-Petch relationship with the decrease in Cr phase spacing.