Improvement of engineering performance of magnesium alloys through rapid solidification technique

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) 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. (orig.)