The Microstructure Evolution of Mg-RE Alloy Produced by Reciprocating Upsetting Extrusion during Hot Compression

Mg-13Gd-4Y-2Zn-0.4Zr (wt. %) alloy bar produced by three passes reciprocating upsetting extrusion (named as RUE-ed bar) exhibited fine grain with the average size of 3.02 μm. Hot compression tests were carried out on Gleeble-3800 unit at different deformation temperatures (653, 683, 713, and 743 K) strain rates (0.001–1 s, 0.01–1 0.1–1 0.5–1 s). This showed work hardening softening stages in hot compression, thermal activation energy was 150 ± 1 kJ/mol constitutive equation was: ε˙=1.80×109[sinh(0.0174σ)]2.47exp[−150×1038.314×T]. Numerous Mg5 (Gd, Y, Zn) phase re-dissolved α-Mg matrix appeared samples during deformation. The movement dislocation stimulated re-dissolution phase. promoted texture strengthening DRX grains growth this experiment. In addition, transformation kinking LPSO played an important coordinating role process compression; 18R-LPSO changed to 14H-LPSO low rate while kinked dominant coordinated high rate.