Structure and properties of magnesium–zinc composite alloys thermomechanically treated

Abstract The properties and microstructure of magnesium–6 zinc alloy and its composites were studied in this investigation. SiC particulates or short glass fibers were used as reinforcement materials with 15 volume fraction percent. The obtained materials were thermomechanically treated as follows; 60% hot extrusion then ageing at suitable conditions. To obtain these conditions, the as-cast materials as well as the as-extruded one were solid solution heat treated and then aged to two different ageing processes (T 5 and double ageing). Metallographic examination, mechanical and wear testing were carried out on the Mg–6Zn alloy and its composites in different conditions. The results showed that the microstructure consists of MgZn 2 phase imbedded in α-rich phase (Mg-rich phase). Composite materials have a finer structure especially after extrusion. The glass composite alloy has a best structure modification. The results of the mechanical properties showed that the composite materials have a higher ultimate tensile strength (UTS) and the yield strength (YS) than unreinforced one while elongation decreased. After extrusion, the UTS, YS and elongation are increased due to the refining of microstructures. On the other hand, thermomechanical treatment improved the UTS and YS while elongation decreased another time. The wear properties show that the reinforcement of the materials improves their wear resistance. Also, the reinforced materials, which are subjected to thermomechanical treatment, have a higher wear resistance than the others. At the same time, the higher mechanical properties and wear resistance were obtained in glass reinforced alloy thermomechanically treated. Fracture surfaces of extruded Mg–6Zn and its composites before and after ageing are studied.