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利用正挤压和往复挤压-正挤压联合工艺制备细晶Mg-6Zn-1Y合金,研究挤压工艺对合金组织的影响。结果表明:挤压比为11.3时,300、340℃正挤压合金晶粒平均尺寸分别为2.7、12.9μm;300℃时再结晶机制为非连续动态再结晶机制,组织不均匀;340℃时为连续动态再结晶机理,组织均匀;挤压比6.1时,300℃挤压合金平均晶粒尺寸为3.2μm。降低挤压温度和增大挤压速率均可以提高组织细化程度。340℃往复挤压5道次后再经255℃正挤压合金组织均匀,平均晶粒尺寸为5.3μm,均匀的细晶组织归因于在往复挤压和正挤压过程中发生了2次动态再结晶。
The effects of extrusion process on microstructure of fine grained Mg-6Zn-1Y alloy were investigated by using positive extrusion and reciprocating extrusion-positive extrusion. The results show that the average grain sizes of the as-extruded alloy at 300 and 340 ℃ are respectively 2.7 and 12.9μm at the extrusion ratio of 11.3. The recrystallization mechanism at 300 ℃ is discontinuous dynamic recrystallization with uneven microstructure. At 340 ℃ For the continuous dynamic recrystallization mechanism, uniform organization; extrusion ratio of 6.1, 300 ℃ extruded alloy average grain size of 3.2μm. Reducing the extrusion temperature and increasing the extrusion rate can increase the degree of refinement. After reciprocating extrusion at 340 ℃ for 5 passes and then extruding at 255 ℃, the microstructure of the alloy was homogeneous and the average grain size was 5.3μm. The uniform fine grain structure was attributed to two dynamic processes during the reciprocating extrusion and the normal extrusion re-crystallize.