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).
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