Local chemistry of a nanocrystalline high-strength Mg 97 Y 2 Zn 1 alloy

The local chemistry of a high-strength nanocrystalline Mg 97 Y 2 Zn 1 alloy produced by a rapidly solidified powder metallurgy process has been characterized by a three-dimensional atom probe (3DAP). The consolidated and extruded rod consists of hcp Mg grains of approximately 150nm size with their basal planes normal to the radial direction of the rod. 3DAP results revealed that the Y and Zn contents vary depending on the grains. Y- and Zn-depleted grains have a hcp structure, while Y- and Zn-enriched grains have a unique long-period stacking of the basal plane designated as 6H-Mg. In the 6H-Mg phase, the enrichment of Y and Zn occurs in one or two atomic layers in the unit cell. The chemical composition of the solute-enriched layer was estimated to be approximately 10 at.% Y and 3 at.% Zn using the 3DAP.