Improved Mechanical Properties of ECAPed Mg-9Gd-2Nd-0.5Zr Alloy Through LPSO Phase Induced by Zn Addition

The effect of Zn addition on the microstructure and mechanical properties of Mg-9Gd-2Nd-0.5Zr alloys during equal channel angular pressing (ECAP) was investigated. Uniformly distributed dynamically recrystallized (DRXed) grains with an average grain size of 2.7 +/- 0.3 mu m were obtained in the ECAPed Mg-9Gd-2Nd-0.5Zr alloy. A large number of Mg5RE phases were found to dynamically precipitate from the matrix, while the uniformly distributed dynamically recrystallized grains with an average grain size of 3.0 +/- 0.3 mu m were obtained in the Mg-9Gd-2Nd-1.6Zn-0.5Zr alloy. In addition, some coarse undynamically recrystallized (un-DRXed) grains existed due to the kinking of the long period stacking ordered (LPSO) phase. A small amount nano-beta(1) phases were dynamically precipitated from the matrix with the exception of the broken (MgZn)(3)RE and LPSO phase. The ECAPed Mg-9Gd-2Nd-1.6Zn-0.5Zr alloy expresses excellent comprehensive mechanical properties (YS = 321 MPa, UTS = 377 MPa, EL = 14.5%) compared with the Mg-9Gd-2Nd-0.5Zr alloy (YS = 317 MPa, UTS = 360 MPa, EL = 9.6%). This can be attributed to the strengthening and toughening effect of the LPSO phase, which not only makes the alloy exhibit a typical bimodal microstructure and improve the strength of the alloy, but also weakens the basal surface texture to improve the plasticity of the alloy.

Automated summary

The effect of Zn addition on the microstructure and mechanical properties of Mg-9Gd-2Nd-0.5Zr alloys during equal channel angular pressing was investigated. The addition of Zn resulted in the formation of uniformly distributed dynamically recrystallized grains with an average size of 3.0 +/- 0.3 μm in the Mg-9Gd-2Nd-1.6Zn-0.5Zr alloy. The alloy exhibited excellent mechanical properties compared to the Mg-9Gd-2Nd-0.5Zr alloy. This can be attributed to the strengthening and toughening effect of the LPSO phase, which improved the strength and plasticity of the alloy.