Formation of profuse long period stacking ordered microcells in Mg-Gd-Zn-Zr alloy during multipass ECAP process

A cast Mg97.1Gd1.8Zn1Zr0.1 (at.%) alloy having long period stacking ordered (LPSO) structures was continuously processed at 375 °C by equal channel angular pressing (ECAP) for 1, 4, 8, 12 and 16 passes. With increasing ECAP passes, more and more rectangular microcells with a width of 0.25-0.5 μm and a length of 0.5-1.5 μm were produced adjacent to the β-phase particles and dynamic recrystallization (DRX) grains. These microcells were actually sandwichs consisting of 14H LPSO phase and α-Mg nano-slices, resulting from the shear effect and high internal temperature of the billet generated by continuous ECAP process. After 16 passes, the ultimate tensile strength of 387 MPa and the elongation of 23% were obtained due to the special microstructure in the alloy.