Hot deformation behavior and dynamic recrystallization mechanism of an Mg-5wt.%Zn alloy with trace SiCp addition

Abstract

The influence of trace (3 vol%) silicon carbide particle (SiCp) addition on the hot deformation behavior of the Mg-5wt.%Zn (Mg–5Zn) alloy was studied through the hot compression test. The activation energy of the Mg–5Zn alloy is decreased by the addition of trace SiCp, which is due to the high dislocations density in particle deformation zone (PDZ) around SiCp stimulates the pipe diffusion. Moreover, the activation energy of the composite also decreases with the increase of the size of PDZ (dPDZ). Additionally, the optimum deformation condition of 3 vol% 20 μm SiCp/Mg–5Zn composite is 693 K and 0.1–0.01s−1 according to the processing map. The instability region of the processing map at 543 K and 1 s−1 disappears with the increase of strain, which is associated with the inhibitory effect of trace SiCp on {101¯2} extension twins and promoting effect on the dynamic recrystallization (DRX) within {101¯1} contraction twins and {101¯1}-{101¯2} double twins by introducing flow localization. Moreover, the DRX behavior of the 3 vol% 20 μm SiCp/Mg–5Zn composite was analyzed by EBSD technology. The DRX mechanisms of the composite at 543 K and 1 s−1 are continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN) and twining dynamic recrystallization (TDRX). With the increase of temperature, the DRX mechanisms are discontinuous dynamic recrystallization (DDRX) and PSN.