Microstructure and properties of the Al-0.5 wt.% Fe alloy wire, copper-clad by electrochemical deposition

Abstract

This study examines the microstructure, mechanical and electrical properties of the copper-clad wires with a core of Al-0.5Fe alloy, obtained by casting into an electromagnetic crystallizer (EMC). The outer copper layer with a thickness of 90 ± 10 μm was applied via electrochemical deposition. Copper cladding of the aluminum wire leads to (without loss of strength and electrical conductivity) a decrease in the ductility to the value less than 2% which is the minimal recommended level of the elongation to failure for the commercially used aluminium alloys. Such drop in ductility also results in the shift of the fracture type to a brittle one. The cause of brittle fracture is the presence of a transition nickel layer required by the technological process of the electrochemical deposition of copper onto aluminium alloy. Annealing at 300 °C for 1 h leads to recovery of the ductility to the original level (4.3% for the cold-drawn Al-0.5Fe alloy wires) with a slight decrease in the ultimate tensile strength to 184 MPa and an increase in the specific electrical conductivity of the bimetallic wire to 60.9%IACS, as well as a change in fracture behavior to ductile. This method is promising for creating the bimetallic aluminum wires with a thin copper layer of controlled thickness and chemical composition to produce conductive elements in which the skin effect could be realized.