Mechanical properties and failure mechanisms of Mg-Zn-Y alloys with different extrusion ratio and LPSO volume fraction

In long period stacking ordered (LPSO) phase containing Mg-Zn-Y alloys, high elastic modulus and deformation kinks of LPSO phase considerably enhance the tensile yield strength, with slight detriment of or benefit to the ductility depending on its volume fraction. In present work, uniaxial tensile tests and fracture toughness tests are carried out using Mg99.2Zn0.2Y0.6, Mg97Zn1Y2, Mg89Zn4Y7 and Mg85Zn6Y9 (at % ) materials with different extrusion ratios. Extrusion processing enhances both strength and ductility due to the recrystallization of Mg grains. Variable plastic deformation mechanisms are activated depending on volume fraction of Mg and LPSO phase as well as their relative size during bending. { 10 1 over bar 2} < 10 1 over bar 1 over bar > tensile twins in Mg grains and deformation kinks in LPSO phase are observed, which dissipate large amount of deformation energy favoring for toughness. However, inherently brittle LPSO phase is detrimental to toughness. Microstructure-motivated empirical models for yield strength and fracture toughness prediction based on rule of mixtures are calibrated by experimental data. Energy release rates of individual mechanisms are estimated, which quantitatively indicate strong Mg/LPSO interaction. (c) 2022 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing University

Automated summary

The high elastic modulus and deformation kinks of the long period stacking ordered (LPSO) phase in Mg-Zn-Y alloys significantly enhance the tensile yield strength, with a slight detriment or benefit to the ductility. Extrusion processing improves both strength and ductility through recrystallization of Mg grains. The activation of different plastic deformation mechanisms depends on the volume fraction and relative size of Mg and LPSO phases.