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A simple cryogenic method for testing of electrical properties of copper and its alloys.

Number: 0083

Author(s) : KRALIK T., KRUTIL V., KRBEC J., VONDRACEK P., BOEHLKE P., SCHULTZE H.

Summary

We present a simple cryogenic method for evaluating the quality of copper and its alloys based on measurements of the Residual Resistance Ratio (RRR) and the electrical conductivity.
The RRR is a measure of the purity and quality of a metallic material, defined as the ratio of the electrical resistivity of the material at room temperature (typically 300 K) to its resistivity at a low temperature close to 4.2 K. The RRR can serve as an indirect indicator of a metal's mechanical properties and thermal conductivity, particularly in high-purity metals. A high RRR value typically indicates fewer impurities and defects in the metal’s crystal structure. This can correlate with improved ductility and reduced brittleness, as impurities and defects act as stress concentrators that weaken the material. Our method was developed for the rapid evaluation of materials at ISI Brno, with such materials lately used as a candidate material for the coils of the new research tokamak COMPASS-U.
The method is based on measuring the electrical resistance of samples with precise geometry. The samples are soldered to contacts on a special pallet, which is connected to the end of a cryogenic probe. The probe is inserted sequentially into liquid helium (LHe), liquid nitrogen (LN2), and a room-temperature bath, where the resistance of the sample is measured under steady-state conditions.

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Pages: 7 p.

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Details

  • Original title: A simple cryogenic method for testing of electrical properties of copper and its alloys.
  • Record ID : 30033908
  • Languages: English
  • Subject: Technology
  • Source: Cryogenics 2025. Proceedings of the 18th IIR International Conference on Cryogenics, Prague, Czech Republic, 7-11 April 2025.
  • Publication date: 2025/04/07
  • DOI: http://dx.doi.org/10.18462/iir.cryo.2025.0083

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