Mechanical Properties of Rolled Copper Foils in Cryogenic and Room‐Temperature Environments

The mechanical properties of high‐purity asymmetric rolled copper foils under cryogenic‐temperature and room‐temperature conditions are studied. The experimental results show that the ultimate tensile stress of the foils increases to a certain value (rolling reduction ratio ≈80%) and then decreases with a decrease in thickness when the tensile tests are carried out in the room‐temperature environment, which monotonically increases with the decrease in the foil thickness when the tensile tests are carried out in a cryogenic environment. The effect on the tensile strength of the copper foil is related to the intrinsic microstructural parameters, such as the dislocation density, grain boundary spacing, and dislocation source. The tensile test results at room and cryogenic temperatures reveal that the elongation decreases with an increase in the rolling reduction ratio. Interestingly, the copper foils of the tensile test at the cryogenic temperature exhibit better elongation than that at the room temperature.