Hot Compression Behavior of Mg–Gd–Y–Zn–Zr Alloy Containing LPSO with Different Morphologies

In this study, hot compression behavior of as-homogenized Mg-9Gd-4Y-2Zn-0.5Zr alloys containing long period ordered (LPSO) phases with different initial morphologies was investigated under a strain rate of 0.01 s at 450 °C. The microstructure, texture evolution and dynamic recrystallization (DRX) mechanism under different strains (0.1, 0.3, 0.5, 0.7, and 1.4) were studied. Under compression conditions, the block-shape phase and deformed α-Mg matrix were regularly arranged vertically in the compression direction (CD). The particle phase (MgRE) and amount of kink bands were produced. The degree of kink increased initially and decreased significantly when the deformation strain reached 1.4. Three DRX mechanisms were produced during the compression process: (i) The block LPSO, Mg5RE and Zr–Zn phase activated DRX through the particle stimulated nucleation (PSN) mechanism. (ii) Several DRX activated on the serrated grain boundary between the two parent grains through discontinuous DRX (DDRX) mechanism. (iii) A large number of kink bands and larger spacing of lamellar LPSO increased the nucleation of DRX through continuous DRX (CDRX) mechanism. The combination of different recrystallization mechanisms has evident effects on grain refinement. DRX increased as compression proceeds, and the texture was gradually weakened.