Evolutions of microstructure and texture of Mg-Gd alloy wires processed by cold drawing

Abstract

High-performance Mg-4.7Gd (wt%) alloy wires were prepared by large-strain multiple-pass cold drawing process. The maximum accumulative true strain (ATS) of Mg-4.7Gd alloy reached as high as 165%, indicating an excellent formability of Mg alloy at room temperature. Evolutions of microstructure and texture as well as mechanical properties of Mg-4.7Gd (wt%) alloy wires were studied in as-extruded and as-drawn condition. A small amount of grain with nano-sizes were observed by transmission electron microscope in the microstructure of as-drawn alloy wires with large ATS. The weak texture components with ∼45° to the transverse direction (TD) drawing direction (DD) instead of the basal texture formed in as-extruded Mg-4.7Gd alloy wire, which was beneficial to the subsequent cold drawing. As ATS increased, grains rotated around the DD and gradually approached the TD. And, the non-basal texture of G4.7 gradually increased with cold drawing due to the addition of Gd, constrained inclined compressive stress, twinning and large strain. This evolution in texture leaded to the formation of <101¯0> fiber texture with <101¯0> parallel to the DD and consequently contributed an extraordinary drawing deformability to Mg alloy.