Electrical conductivity and tensile properties of severely cold-worked Cu-P based alloy sheets

The electrical conductivity of Cu-P based sheet alloys tended to decease with increase of the total amount of final cold rolling, while alloy tensile strength proportionally increased. When the cold rolling was carried out at an extremely low temperature, the tensile strength was more remarkably increased, even though the degree of reduced conductivity was generally similar to that found in the ordinary cold rolling process. It is well known that strain hardening reduces the electrical conductivity of pure Cu and Cu alloys; however, in this work it is reported that the degree of reduction is apparently larger than previously thought. TEM analysis revealed that various fine P-containing precipitates were formed in the experimental alloys. The unstable interface between the coarse P-containing precipitates and the Cu matrix is postulated to be responsible for the significant drop of conductivity.