Abstract: The definition of residual resistivity ratio(RRR) was introduced and the significance of RRR for application of low-temperature superconducting metallic materials was analyzed. A heat treatment program for pure copper and high-purity aluminum was developed, and the residual resistivity ratio of the pure copper and high-purity aluminum was measured before and after heat treatment referring to GB/T 25897—2020/IEC 61788-4:2020 Residual resistivity ratio measurement—Residual resistivity ratio of Nb-Ti and Nb₃Sn composite superconductors. The test results show that heat treatment can effectively improve the RRR of the pure copper and high-purity aluminum, and vacuum heat treatment is more effective than ordinary atmospheric heat treatment; the processing state before heat treatment and the material source are different, although the difference in the RRR before heat treatment is small, but there is often a large difference after heat treatment, and it is recommended that the RRR value after heat treatment must be referred to when selecting materials for the design of the low-temperature thermal conductivity(LTC).

Key words: high-purity copper, high-purity aluminum, low-temperature superconductivity, residual resistivity ratio (RRR), heat treatment