Development of Mg–6.0%Zn–1.0%Y–0.6%Ce–0.6%Zr magnesium alloy and its microstructural evolution during processing

A strong and ductile Mg–6.0%Zn–1.0%Y–0.6%Ce–0.6%Zr alloy was developed. The alloy was first cast into billets which were rapidly solidified into ribbons, comminuted and extruded. Some of the extrusions were subjected to reciprocal extrusion processing. The microstructures of the alloy prepared by the different processes were analyzed by optical microscopy (OM) as well as high resolution scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM). The microstructure of the cast consisted of coarse grains with average grain size of about 45 μm with intermetallic networks at grain boundaries. The microstructure of the extrusions made of rapidly solidified chips was not uniform; it was fine at the circumference, but coarser in the central area. A low density of defects in the form of unwelded rapidly solidified (RS) ribbon particles in the center of the extrusion was also present. The microstructure of the alloy subjected to reciprocating extrusion was more uniform with average grain size of 1.3 μm and homogeneously dispersed strengthening particles 80 nm in diameter.