On the relationship between the microstructure and electrical resistivity of copper used in superconducting composites

The relationship between the electrical conductivity anti microstructure of copper samples of 99.99 wt % purity obtained by vacuum electron-beam melti ng has been studied. The miclostructure was studied by transmission electro n microscopy and optical metallography. The analysis of the content of impu rity elements was performed by mass spectrography and laser mass spectromet ry, A correlation was established between the parameter R-273 (K)/R-4.2 K t he concentration of oxygen, and the amount of precipitates in copper. The d ifference in the values of the parameter R-273 K/R-4.2 K observed in the sa mples studied was shown to be due to differences in microstructure features such as the extension of grain boundaries and the concentration of precipi tates of second phases.