On the γ′ and W strengthening precipitates in Dy and Zn microalloyed magnesium alloys

Abstract Microstructure and precipitation behaviors of the aged Mg−2Dy−0.5Zn (wt.%) ternary alloy were investigated by atomic-scale high angle annular dark-field scanning transmission electron microscopy. It is confirmed that the γ′ basal platelets and the W (Mg3Dy2Zn3) nanoparticles play a crucial role in precipitation strengthening and correspond to the peak hardness of age-hardening response in the Dy and Zn microalloyed magnesium alloy. Furthermore, the findings also reveal that most W particles always nucleate on the γ′ basal platelet and grow between adjacent two γ′ platelets. It constrains significantly the coarsening and final size of W particles, and postpone performance degradation of alloys.