Effect of Cold Drawing on Electrical and Mechanical Properties of Cu-5 at% Zr Alloy

抄録

The effects of cold drawing on electrical- and mechanical properties of Cu-5 at% Zr alloy were examined as a function of a drawing ratio (η), and were discussed in relation to the microstructural evolution under drawing process. Microstructure was changed by drawing into the fine fibrous elongated structure with alternating phases of Cu solid solution (Cu_ss) and Cu₉Zr₂ intermetallic (Cu₉Zr₂). Electrical conductivity increases by cold drawing up to η=5.9 as compared with that for the as-cast state, whose relative electrical conductivity is 24 %IACS (IACS: international annealed copper standard). The %IACS shows a maximum value of 36% IACS at η=2.2. It was suggested that the microstructural formation of net-like Cu_ss phase parallel to the drawing direction enhanced the electrical conductivity by drawing process. Moreover, the strength increased with the increase in the drawing ratio. The increase in the strength can be reasonably explained by the effect of work hardening and the refinement of microstructure. Thus, it was found that the combination of high electrical conductivity of 31∼36% IACS and high tensile strength of 1113∼1798 MPa was achieved in Cu-5 at% Zr alloy by cold drawing.