The maximum solubility of Y in α-Mg and composition ranges of Mg24Y5 − x and Mg2Y1 − x intermetallic phases in Mg–Y binary system

The solid solubility of Y in the α-Mg matrix and composition homogeneity ranges of Mg24Y5 − x and Mg2Y1 − x phases in the Mg–Y binary system are important parameters to understand solid–solution- and aging-strengthening effects of Mg–Y-based alloys. However, they are different among the various assessed Mg–Y phase diagrams which are based on limited experimental data, especially at temperatures below ∼850 K. Our experimental results by using both diffusion couple technique and alloy method are in good agreement each other, but much different from the presently accepted Mg–Y phase diagram. The results show that the maximum solubility of Y in the α-Mg matrix is 4.7 at.% Y, much larger than the current phase diagram. The determined composition homogeneity ranges of Mg24Y5 − x and Mg2Y1 − x phases are much wider than the present ones and shift remarkably to the Mg-rich corner of Mg–Y phase diagram.

Figure optionsDownload as PowerPoint slideResearch highlights▶ By using diffusion couple technique and alloy method, the determined maximum solubility of Y in the α-Mg matrix is 4.7 at.% Y, much larger than the current phase diagram. The composition homogeneity ranges of Mg24Y5 − x and Mg2Y1 − x phases are much wider than the present ones and shift remarkably to the Mg-rich corner of Mg–Y phase diagram.