Spheroidization behavior of W phase and transformation process of LPSO phase during solid- solution treatment in Mg-Zn-Y-Mn-Ti alloy

The effect of solid-solution treatment on the microstructure and mechanical properties of Mg93.5Zn2.5Y2.5Mn1Ti0.5 alloys was studied by the optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindentation tester, and an electronic universal testing machine. The results showed that the fishbone-like W phase can be transformed into the spherical W phase by the solution treatment, and the partial bulk 18R LPSO phase along grain boundaries can be transformed into the intragranular lamellar 14H LPSO phase. The spheroidization of W phase and the formation of intragranular 14H LPSO phase effectively improved the me-chanical properties of considered alloys. With the increase of solid-solution time, the yield strength, tensile strength, and elongation of alloys initially increase and then decrease. The biggest improvement in mechanical properties was observed for alloys subjected to solid -solution treatment for 40 h; the yield strength, tensile strength, and the elongation were 165 MPa, 265 MPa, and 11.5%, respectively.(c) 2022 The Authors. 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/).

Automated summary

The effect of solid-solution treatment on the microstructure and mechanical properties of Mg93.5Zn2.5Y2.5Mn1Ti0.5 alloys was investigated. The results showed that solid-solution treatment transformed the fishbone-like W phase into spherical W phase and the bulk 18R LPSO phase along grain boundaries into intragranular lamellar 14H LPSO phase. The spheroidization of W phase and the formation of intragranular 14H LPSO phase effectively improved the mechanical properties of the alloys. The alloys subjected to 40 hours of solid-solution treatment exhibited the greatest improvement in mechanical properties, including yield strength, tensile strength, and elongation.