Effects of extrusion temperature on microstructure evolution and mechanical properties of heterogeneous Mg-Gd alloy laminates via accumulated extrusion bonding

摘要

The influence of extrusion temperature on microstructure and mechanical properties of heterogeneous Mg-1Gd/Mg-13Gd laminate prepared by accumulated extrusion bonding was investigated. The results reveal that the Mg-1Gd/Mg-13Gd laminate forms a significant difference in grain size between the successive layers when extruded at 330 ?, and this difference gradually disappears as the extrusion temperature increases from 380 to 430 ?. Besides, the growth rate of recrystallized grains in fine-grained layers is faster than that in coarse-grained layers. Moreover, the diffusion ability of Gd element increases with elevating extrusion temperatures, promoting the increase and coarsening of precipitates in fine-grained layers. Tensile tests indicate that the sample extruded at 380 ? has a superior combination of strength and ductility. This is mainly attributed to the synergy of the heterogeneous texture between coarse and fine-grained layers, hetero-deformation induced strengthening and hardening. The fine-grained layers facilitate the activation of prismatic slips, while coarse-grained layers make it easier to active basal and pyramidal slips, especially for the sample extruded at 380 ?. The activation of pyramidal slips contributes to coordinating further plastic deformation.