Effect of Joule-Heating Treatment on the Microstructure and Physical Properties of 16-Stranded Compressed Copper Wires

Compressed wires are produced by cross-sectionally compressing stranded conductors, which results in a smaller conductor diameter. This also leads to a lower weight wire, because a thinner external insulated coating can be used, compared to the low-voltage wires typically used in automobiles. However, a post production heat treatment of the compressed wires is required because plastic deformation occurs during compression after drawing the wires. In this study, the work hardening of stranded compressed copper wires was controlled by Joule-heating, and the resulting changes in microstructure, mechanical, and electrical properties after various annealing voltages (0, 25, 27, 31, 35, and 39 V) were observed. The results confirmed that as the annealing voltage increased from 0 to 31 V, the anisotropic deformation texture with a <111> orientation as the main component was reduced, and micrograins were generated throughout the stranded wires via recrystallization. At an annealing voltage above 31 V, the grains grew to be more than twice as large as those before heat treatment. At an annealing voltage of 31 V these structural changes contribute to the elongation increase of the compressed wires to 28.34%, and an improvement in electrical resistance to 145.85 mΩ.

Testing short distance anisotropy in space

The isotropy of space is not a logical requirement but rather is an empirical question; indeed there is suggestive evidence that universe might be anisotropic. A plausible source of these anisotropies could be quantum gravity corrections. If these corrections happen to be between the electroweak scale and the Planck scale, then these anisotropies can have measurable consequences at short distances and their effects can be measured using ultra sensitive condensed matter systems. We investigate how such anisotropic quantum gravity corrections modify low energy physics through an anisotropic deformation of the Heisenberg algebra. We discuss how such anisotropies might be observed using a scanning tunnelling microscope.