Microstructure and phase composition in die cast Mg-Nd alloy containing Zn and Zr

The microstructure of the as-cast Mg-3.1Nd-0.45Zr-0.25Zn (wt.%) alloy was investigated. It consists of alpha-Mg matrix, a divorced intergranular phase and small Zr-containing particles. Scanning electron microscopy equipped with energy dispersive spectroscopy analysis on transmission electron microscopy samples was carried out in order to eliminate the Mg matrix contribution to the quantitative analysis results and to reveal the intergranular phase composition which was found to be Mg12-xZnxNd (x similar to 0.31) (space group I4/mmm) with a bet crystal structure. The lattice parameters (a = 1.029 nm and c = 0.591 nm) were found using X-ray diffraction with the least squares refinement technique. The combination of different characterization techniques indicates that Mg atoms are substituted by Zn atoms without a change in the crystal structure.