A method of forming a flat bar is provided. A tube is provided having an inside surface and an outside surface. The outside surface of the tube can be clad with a nickel or stainless alloy material. A helix shaped strip can be cut from the tube. The helix shaped strip can be uncoiled to form an uncoiled strip, and the uncoiled strip can be straightened and flattened to meet mill standards.

The present disclosure provides a copper-coated aluminum wire material including an aluminum wire material and a copper thin film coating the aluminum wire material that a space factor of the thin copper film is in the range of 0.2% to 4%.

Disclosed herein are composite wire materials with advantageous composition and structure that can provide improved mechanical properties. An example composite wire material includes a core wire including nickel (Ni), and a graphene-based layer on a surface of the core wire. Also disclosed are methods of making the composite wire material.

A superconducting wire comprises a MgB.sub.2 filament, a base material, a high-thermal expansion metal, and a stabilizing material. The high-thermal expansion metal is a metal (for example, stainless steel) having a higher thermal expansion coefficient at room temperature than the MgB.sub.2 and the base material (for example, iron or niobium). The manufacturing method includes a step of packing a mixed powder in a first metal pipe, a step of performing wire-drawing on the first metal pipe formed of the metal to be the base material, a step of producing a composite wire by accommodating the first metal pipe in a second metal pipe formed of the high-thermal expansion metal and the stabilizing material, a step of performing wire-drawing on the composite wire, and a step of performing heat treatment.