Effect of Mg content on mechanical properties and electrical conductivity of ultrafine-grained Al-Mg-Zr wires produced by ECAP-Conform and drawing

We propose pathways to produce high-strength thermal resistant Mg-doped Al-Zr-based conductors to be manufactured in the form of ultrafine-grained wires via deliberate thermomechanical treatment, including aging, continuous equal-channel angular pressing and cold drawing. Al-0.97Mg-0.35Zr and Al-1.17Mg-0.34Zr (wt.%) alloys were chosen as objects for investigation to reveal the effect of Mg on the alloys' properties in the processed states. Prior to deformation, the initial rods of the studied alloys were aged at 400 degrees C for 72 h to attain precipitation of nano-sized particles of the metastable phase Al3Zr (L12) in the aluminum matrix. The following refinement of microstructure in the aged alloys by severe straining followed by cold drawing allows achieving a promising combination of ultimate tensile strength over 320 MPa, plasticity with elongation to failure over 2% and electrical conductivity about 50% IACS. We show that the produced wires exhibit thermal resistance similar to that of the commercial high-strength heat-resistant aluminum alloy (KTAL) type AT2 wire, but with a markedly superior strength. The Mg concentrations and parameters of thermal and mechanical processing that maintain a reasonable trade-off between high strength and acceptable electrical conductivity are discussed on the basis of the presented and earlier reported data to produce high-performance heat-resistant UFG Al-Mg-Zr wires.