Composite electric wire

1. A composite electric wire comprising:

an electric wire body composed of center conductors arranged in a 1+6 configuration; and

twelve outer-layer conductors arranged to extend in a longitudinal direction along outer circumferences of the center conductors and to enclose the center conductors,

wherein each of the center conductor is composed of at least one copper element wire, and the outer-layer conductors are composed of a plurality of copper-coated aluminum element wires,

wherein the center conductors are sectionally positioned at a center portion of the electric wire body in a plane perpendicular to a longitudinal direction of the electric wire body, and the outer-layer conductors are sectionally positioned in an outer circumference portion around the center portion, and

wherein the outer-layer conductors make contact at their outer circumferences with the outer circumferences of the center conductors to make their electric connections.

2. The composite electric wire as claimed in claim 1 ,

wherein each of the plurality of copper-coated aluminum element wires is a copper-clad aluminum element wire made by diffusion bonding at a bonded interface between a metal including aluminum and copper.

3. The composite electric wire as claimed in claim 2 ,

wherein copper included in the at least one copper element wire and copper composing the plurality of copper-coated aluminum element wires are the same copper material.

4. The composite electric wire as claimed in claim 1 ,

wherein copper included in the at least one copper element wire and copper composing the plurality of copper-coated aluminum element wires are the same copper material.