Rapid corrosion rates and high mechanical properties of as-extruded Mg-Er-Ni alloys by introducing LPSO and g" phases

The Mg-Er-Ni alloy with comparable strength and solubility was prepared by controlling the Ni content. The mechanical properties and corrosion mechanism of alloys with long -period stacking ordered (LPSO) phase, as well as those with both LPSO and y" phases, were investigated and clarified. This study focused on investigating the underlying reasons for the high mechanical strength and fast corrosion rate of the Mg-13Er-3Ni alloy with LPSO and y' phases. The highest corrosion rate of the Mg-13Er-3Ni (wt.%) alloy is not only associated with the high volume fraction of the LPSO phase, which provides a larger zone for the corrosion cathode rather than forming a corrosion barrier, but also linked to the introduction of the y' phase that forms new sites for galvanic corrosion and avoids the formation the Er2O3 corrosion product film with corrosion-resistant. Moreover, The high mechanical properties of Mg-13Er-3Ni alloy are mainly attributed to the texture strengthening, dislocation strengthening and the second phase reinforcement that were caused by high volume fraction of LPSO phase and the precipitation of lamellar y" phase in Mg matrix. Generally, Compared to the Mg-13Er-1.5Ni (wt.%) alloy, the corrosion rates and mechanical strength of Mg-13Er-3Ni (wt.%) alloy were increased significantly by 302.8% and 50.3%, respectively, by coupling the LPSO and y' phases. Its ultimate tensile strength of 445 MPa and corrosion rare of 128.5 mg cm -2 h-1, which provides a new high strength and rapid corrosion Mg alloy materials for fracturing tools application.& COPY; 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).