Wire, superconducting metal alloy

Some scientists have foregone the ceramics altogether and attempted to fabricate wire out of metal alloys that can superconduct at temperatures warmer than normal for a metal. At the Massachusetts Institute of Technology, for example, one team has made a superconductor from europium—a soft, silvery metal that was once in short supply but is now more easily acquired—barium, and copper. The alloy apparently works well at 90° K, which means it can run on liquid nitrogen moreover, it is more easily fabri-... 

Niobium alloyed with germanium becomes a superconductor of electricity that does not lose its superconductivity at 23.2° Kelvin as large amounts of electrical current are passed through it, as do some other superconductive alloys. In the pure metallic state, niobium wires are also superconductors when the temperatures are reduced to near absolute zero (—273°C). Niobium alloys are also used to make superconductive magnets as well as jewelry. 

The samples studied were composites with f.c.c. metal matrices (Cu) and superconducting wires of b.c.c. alloys. It is known that, with decreasing temperature, the plasticity increases in f.c.c. metals and decreases in b.c.c. metals. Therefore, the observed cable brittleness seems to result from the brittleness of the superconducting wire itself. This is supported by the results of mechanical tests on separate wires etched from a composite. The tests showed that when temperature decreases from 77 to 4 K, the yield increases (to about twice that at room temperature), and there is a sharp reduction of the relative elongation to 0.1 to 0.2%. 

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