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采用熔铸和大变形轧制制备了Mg-6Li-3Zn合金板材,研究了合金的高温变形行为、显微组织、空洞与位错蠕变机制.在623 K和1.67×10~(-3)s~(-1)条件下获得了300%的最大延伸率.OM,TEM和SEM观察显示,合金带状晶粒组织在573 K和1.67×10~(-3) s~(-1)条件下发生显著的动态再结晶,亚晶轮廓不清晰,位错分布比较均匀.合金在573-623 K和1.67×10~(-3) s~(-1)条件下断裂形式为韧性断裂.获得了新型的位错黏性滑移与位错攀移转变蠕变机制图,表明Mg-6Li-3Zn合金带状晶粒组织在573 K和1.67×10~(-3) s~(-1)条件下高温变形机制为晶格扩散控制的位错黏性滑移,其应力指数为3(应变速率敏感性指数0.33),变形激活能为134.8 kJ/mol,与Mg的晶格扩散激活能相同.获得了新型的考虑聚合的空洞长大图,合金在573 K和1.67×10~(-3) s~(-1)条件下的空洞长大机制为塑性控制的空洞长大.
Mg-6Li-3Zn alloy sheets were prepared by casting and large deformation rolling, and the mechanisms of high-temperature deformation, microstructure, cavitation and dislocation creep of the alloys were studied.At 623 K and 1.67 × 10 -3 s ~ (-1), the maximum elongation of 300% was obtained.The OM, TEM and SEM observations showed that the banding grain microstructure of the alloy under the conditions of 573 K and 1.67 × 10 ~ (-3) s ~ (-1) Significant dynamic recrystallization occurred, the subgrain profile was not clear and the dislocation distribution was more uniform.The fracture mode was ductile fracture under the condition of 573-623 K and 1.67 × 10 -3 s -1, The new dislocation viscous slip and dislocation climbing creep mechanism map shows that the banding grain structure of Mg-6Li-3Zn alloy at 573 K and 1.67 × 10 -3 s -1 conditions The high-temperature deformation mechanism is the dislocation viscous slip controlled by lattice diffusion. The stress exponent is 3 (strain rate sensitivity index is 0.33), and the deformation activation energy is 134.8 kJ / mol, which is the same as that of Mg. The new cavity growth diagram was obtained considering the polymerization. The mechanism of cavity growth under the condition of 573 K and 1.67 × 10 -3 s -1 was plastic controlled growth of cavity.