IMPROVEMENT OF ENGINEERING PERFORMANCE OF MAGNESIUM ALLOYS THROUGH RAPID SOLIDIFICATION TECHNIQUE

Magnesium-Aluminium-Zinc powders are produced by centrifugal atomizati on. The microstructural refinement achieved by rapid solidification ca n be maintained throughout the extrusion process. The consolidated Mg- xAl-yZn alloys (x = 8,15 or 20, y = 1 or 3 at %) exhibit enhanced mech anical properties and corrosion behaviour as well. Structural hardenin g is expected from the Mg-Zn system (GP zones)[1] and from decompositi on of the supersaturated Mg-Al solid solution (Mg17Al12 precipitation) . Furthermore a higher isotropy is expected from the reduction in grai n size. The tensile strength of the alloy, larger than 400 MPa, is an increasing function of the aluminium content which must be kept below approximate to 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 electrochemi cal study of corrosion rate and mechanism is on the way to confirm thi s first observation. This work gives additional informations to previo us results obtained on ribbons with a lower content in aluminium [2].