Dislocation-induced ?? precipitation behavior and strength-ductility synergistic enhancement in Mg-Gd-Y-Zr-Ag alloy

In this work, the microstructure, precipitation behavior and mechanical properties of a multi-directional forged and age-treated Mg-8.9Gd-1.8Y-0.5Zr-0.2Ag (wt%) alloy were investigated. A mixed structure composed of dislocation-induced chain-like distributed beta' phases, homogeneously distributed beta' phases and precipitation free zones (PFZs) is observed in the as-aged alloy. With the extension of aging time after reaching peak hardness, an unusual platform appears on the aging hardening curve, and an attractive result that the strength and ductility increase simultaneously is obtained. The alloy aged at 498 K exhibits the optimal combination properties of strength and ductility, with an ultimate tensile strength (UTS) of 374 MPa, a yield tensile strength (YS) of 279 MPa and an elongation (EL) of 17.9%. The excellent strengthductility property is attributed to the synergistic effect of precipitate-induced strengthening and PFZ-induced ductility enhancement. As the aging temperature was reduced to 473 K, the fraction of PFZs decreased significantly, leading to an increase in strength at the cost of a sharp decrease in ductility.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the microstructure, precipitation behavior, and mechanical properties of a multi-directional forged and age-treated Mg-8.9Gd-1.8Y-0.5Zr-0.2Ag (wt%) alloy. The as-aged alloy exhibits a mixed structure consisting of dislocation-induced chain-like distributed beta' phases, homogeneously distributed beta' phases, and precipitation free zones (PFZs). The alloy aged at 498 K shows the optimal combination properties of strength and ductility. However, decreasing the aging temperature to 473 K results in a significant decrease in ductility at the cost of increased strength.