Precipitation behaviors and mechanical properties of a solution-treated Mg-Gd-Nd-Zn-Zr alloy during equal-channel angular pressing process

Abstract

A magnesium alloy processed by equal-channel angular pressing (ECAP) exhibited excellent microstructure refinement and improved strength and hardness. The comprehensive mechanical properties of magnesium alloys have supported the expansion of their applications in the automotive, aerospace, and biomedical industries. Herein, pre-treatment of a solution-treated Mg-2.9Gd-1.5Nd-0.3Zn-0.3Zr alloy was conducted to investigate the precipitate behavior and microstructure evolution during the ECAP process. β1 phase grains quickly precipitated from the solution-treated alloy, which accelerated grain refinement and enhanced the ductility after the ECAP process, as compared to the as-cast alloy reported in our previous study. Moreover, spherical precipitates (∼200 nm) and fine phases (∼100 nm) precipitated along the stripe-like Zn2Zr3 phase, which formed a kabap-like structure dispersing homogeneously in the solution-treated alloy during the ECAP process. Owing to grain refinement, dislocations, spherical β1 precipitates, and texture evolution, the solution-treated alloy after eight passes of ECAP exhibited good comprehensive mechanical properties, with the ultimate tensile strength, yield strength, and elongation values reaching 210.9 MPa, 263.9 MPa, and 27.9%, respectively.

Keywords

• Mg-Gd-Nd-Zn-Zr alloy
• Precipitations
• Solid solution
• ECAP
• Mechanical properties