Mechanism of Abnormal Strength-Electrical Conductivity Relation for an Al-Fe Alloy Wire

Abstract

Excellent strength and electrical conductivity are of great significance for Al wires applied on overhead transmission lines, since the strength and the electrical conductivity are mutually exclusive. In this paper, the strength-electrical conductivity relation of an Al-1.13 wt.% Fe wire fabricated by cold drawing process was investigated by means of microstructure characterization, tensile test, electrical test and theoretical calculation. At the initial stage of the cold-drawing deformation, the strength and the electrical conductivity exhibit a traditional trade-off relation. Surprisingly, the strength-electrical conductivity relation turns to be abnormal as the area reduction exceeds a critical value, 61.9%. The particular phenomenon can be well explained by the formation of the elongated grains. Additionally, the Fe-contained nano-scale precipitates together with the low solubility of Fe element also have an outstanding contribution to the strength and the electrical conductivity of Al-Fe alloy wire. Consequently, the elongated grains, the <111> texture, the low solubility and the nano-scale precipitates are proposed as four mechanisms for designing and preparing high strength-high electrical conductivity Al wire.

Keywords: Al-Fe wire, Strength, Electrical conductivity, Cold drawing, Microstructure evolution