Strength and electrical conductivity of Cu-Al alloy sheets by cryogenic high-speed rolling

Cryogenic high-speed rolling (C-HSR), where the specimen cooled in liquid nitrogen is supplied to rolls at rotating 1500 m/min at room temperature, was carried out with Cu x Al (x = 3.1 and 6.8 mass%) alloy to investigate mechanical properties and electrical conductivities. After 2-pass rolling, the tensile strength was 665 MPa and 841 MPa in case of Cu-3.1 mass% Al and Cu-6.8 mass% Al, meanwhile, conventional low-speed (5 m/ min) cold rolling (LSR) showed 605 MPa and 805 MPa, respectively. The balance of strength - electrical con-ductivity improved in the case of C-HSR compared to LSR. This trend was clearly observed in Cu-3.1 mass% Al. Yield strength and electrical conductivity were predicted using the modified Hall-Petch equation and modified Mayada and Shatzkes (MS) model. It is formed C-HSR increased the accumulation of dislocation density as well as decreasing mean grain size and activation of deformation twins. On the other hand, increase of dislocation density was dominant to contribute the electrical resistivity.

Automated summary

C-HSR rolling can improve the balance of mechanical properties and electrical conductivity of Cu x Al alloy by increasing dislocation density and reducing grain size.