Improvement of engineering performance of magnesium alloys through rapid solidification technique

Abstract
Magnesium-Aluminium-Zinc powders are produced by centrifugal atomization. The microstructural refinement achieved by rapid solidification can be maintained throughout the extrusion process. The consolidated Mg-xAl-yZn alloys (x = 8,15 or 20, y = 1 or 3 at %) exhibit enhanced mechanical properties and corrosion behaviour as well. Structural hardening is expected from the Mg-Zn system (GP zones)[1] and from decomposition of the supersaturated Mg-Al solid solution (Mg₁₇Al₁₂ precipitation). Furthermore a higher isotropy is expected from the reduction in grain size. The tensile strength of the alloy, larger than 400 MPa , is an increasing function of the aluminium content which must be kept below ≈ 15 at % in order to achieve a reasonable ductility. The benefits brought by rapid solidification to corrosion resistance are evident on weight loss tests in 3% salt water. A complete electrochemical study of corrosion rate and mechanism is on the way to confirm this first observation. This work gives additional informations to previous results obtained on ribbons with a lower content in aluminium [2].