Improving the corrosion and mechanical properties of Mg-8Gd-3Y-0.4Zr alloy synergistically via regulating micro-galvanic corrosion and dislocation density

Abstract

This study aims to process Mg alloys using rotary swaging technique to enhance their corrosion resistance and mechanical properties. By optimizing the rotary swaging technology, precise control over the Mg alloy structure was achieved, manifesting as the refinement of grains, the generation of high-density dislocations, the decrease of potential difference between second phase and Mg matrix, and a more uniform distribution of second phase. Microstructural analysis and mechanical tests confirmed the beneficial effects of grains refinement and high-density dislocations on mechanical properties of Mg alloys. Further corrosion performance tests demonstrated that the grain refinement and weak micro-galvanic corrosion caused by low potential difference between second phase and Mg matrix, and a more uniform distribution of second phase effectively improve the corrosion resistance of Mg alloys. Through rotary swaging, the corrosion rate of Mg-8Gd-3Y-0.4Zr (GW83) alloy decreased from 7 to 0.4 mm/y and the tensile stress increased from 210 to 435 MPa synergistically. This research offers a new approach for optimizing the processing of Mg alloys, demonstrating feasibility and potential application prospects in both mechanical and corrosion performance.