Microstructure of the Mg-4Y-3RE-Zr (WE43) Magnesium Alloy Produced by 3D Printing

Abstract

In this study, the three microstructure of the as-cast, hot-extruded, and 3D printed Mg-4Y-3RE-Zr (WE43) magnesium alloy was studied. The selective laser melting (SLM) process was used for 3D printing. The study was aimed at mapping the microstructure of a 3D printed magnesium alloy produced by the SLM process. Magnesium alloys made in the form of 3D printing are relatively new production processes. The study therefore this process compared with current processes, which are now well known and mapped. It was therefore studied the microstructure produced by three different processes of production. The microstructure and chemical composition of present phases were studied using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Based on the microstructural examination, significant differences were found between the materials produced by different production processes. The microstructure of the as-cast alloy consisted of relatively coarse α-Mg dendrites surrounded by eutectics containing intermetallic phases rich-in alloying elements. During hot extrusion, the eutectics fragmented into fine particles which arranged into rows parallel to the extrusion direction. The 3D printed alloy was characterized by significantly refined microstructure due to a high cooling rate during the SLM process. It consisted of very fine dendrites of α-Mg and interdendritic network enriched-in the alloying elements. In addition, there were also oxides covering original powder particles and the material showed also some porosity that is a common feature of 3D printed alloys.