Significant refinement of 18R-LPSO phase and enhancement of mechanical properties in Mg97Y2Zn1 alloy through an industrially viable processing method

Abstract

In this study, an innovative and simplified deformation strategy involving pre-compression followed by hot extrusion was developed, which could be effectively executed as a single-step process in industrial production to refine the 18R-long period stacking ordered (LPSO) structure in magnesium alloys. Post-deformation analysis reveals significant enhancements in the mechanical properties of the alloy, with a tensile yield strength of 413 MPa, an ultimate tensile strength of 485 MPa, and a fracture elongation of 11.2%, surpassing those of other one-step deformed Mg₉₇Y₂Zn₁ alloys. Quantitative results demonstrate that increasing the pre-compression amount from 1.3% to 11.6% correlates with heightened kinking and improved dispersion of the 18 R phase. The 18 R phase refinement is observed following hot extrusion, with the average size decreasing to 3.3 μm for the alloy after 11.6% pre-compression and extrusion along the vertical direction (11.6%-VHE). A similar trend is also noted in the average size reduction of α-Mg grains. This substantial refinement of both α-Mg grains and 18 R phase particles is the primary reason for the enhanced mechanical properties displayed by the 11.6-VHE alloy. This study is expected to inspire the research and development for high-strength Mg alloys containing LPSO with industrial-scale production.