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室温下对AZ31镁合金进行多向多道次变形,制备亚微米和纳米级细晶镁合金.通过OM,SEM/EBSD及TEM观察研究不同累积应变量的显微组织及取向演化.发现低应变多向多道次压缩变形可避免镁合金室温变形下的迅速失稳断裂,能够累积很大的真应变;变形初期晶粒中产生大量{1012}c轴拉伸孪晶,随后c轴压缩孪晶的密度逐渐增加且均匀分布于晶粒内,孪晶分割细化原始晶粒的同时,压缩孪晶诱发的动态再结晶开始沿孪晶密集与交叉处产生,将组织进一步细化;细晶区随着变形道次的增加逐渐增多,15个道次后整个组织被均匀细化至80—150 nm;且单道次变形量Δε在0.05—0.1之间取值越大,晶粒细化效果越显著,细晶分布越均匀.
Microstructures and orientation evolution of AZ31 magnesium alloy were investigated by OM, SEM / EBSD and TEM observations at submicron and nanometer level for multi-strain and multi-pass deformation at room temperature.It was found that low strain The multi-directional and multi-pass compression deformation can avoid the rapid failure of magnesium alloy under room temperature deformation and can accumulate a large true strain. In the early stage of deformation, a large number of {1012} c-axis tensile twins are generated in the grains, The density of the crystal gradually increases and evenly distributed in the grains. The twins disintegrate and refine the original grains, while the dynamic twinning induced dynamic recrystallization begins to occur along the twins and the intersections. The fine grains The area gradually increases with the increase of deformation pass. The whole structure is uniformly refined to 80-150 nm after 15 passes, and the greater the value of single-pass deformation Δε is between 0.05-0.1, the grain refinement The effect is more significant, more uniform distribution of fine grain.