In the automotive industry, due to the increasing demand for energy conservation and emission reduction, the demand for lightweight wire harnesses is increasing, and weight reduction of wire harnesses is imperative. In addition, the soaring price of copper has prompted the automotive industry to choose aluminum as a substitute with higher cost-effectiveness than copper.

Although aluminum wire has disadvantages such as low conductivity, low tensile strength, poor processability, and strong surface insulation oxide film, its application is increasing, and related technologies and research are becoming increasingly mature.

The aluminum alloy used for manufacturing automotive aluminum wires requires high tensile strength and high conductivity. Pure aluminum (1060:99.6% purity) is used for general industrial purposes, with a conductivity of up to 62% IACS. However, after annealing, it exhibited a lower tensile strength of 70 MPa (4). For the application of automotive wire, it is necessary to improve its tensile strength through alloying.

Solid solution strengthening is an effective measure to improve the tensile strength of metals. However, this method leads to a significant decrease in conductivity. Meanwhile, a larger mismatch strain (MS) * 3 (5) is also expected to improve the tensile strength of the metal. For the application of automotive wires, it is necessary to suppress the decrease in conductivity and improve tensile strength. Therefore, if an element provides a large amount of MS at low solid solution levels, it is considered an effective alloying element.