采用Gleeble-1500热模拟机, 在变形温度750-900℃, 应变速率0.01-10 s$^{-1}$的条件下, 对连续柱状晶BFe10-1-1合金进行了高温压缩变形, 研究了合金的动态再结晶行为. 结果表明, 动态再结晶温度在850 ℃左右; 热激活能Q= 427.937 kJ/mol, 高于同成分的等轴晶BFe10-1-1合金; 当ln Z<43时, 合金发生部分动态再结晶; 当43≦ln Z≦51时, 发生部分动态再结晶(850和900℃)或不发生动态再结晶(750和800℃), 为该合金发生动态再结晶的中间区域; 当ln Z>51时, 该合金不发生动态再结晶. 存在发生动态再结晶的ln Z值中间区域以及热激活能较高, 表明具有连续柱状晶组织的金属与等轴多晶金属发生动态再结晶的机理有所不同. 在本文工艺参数范围内, 随应变速率增大, 合金发生动态再结晶的区域有所扩大; 动态再结晶晶粒易在合金晶界处以晶界弓弯方式形核, 形成的再结晶晶粒在晶界扩张的同时, 在晶内形成孪晶, 并以“孪生动态再结晶”方式演变成晶粒带.
Dynamic recrystallization behavior of a Cu-based alloy BFe10-1-1 with continuous columnar grains was investigated by hot compression test. Specimen was compressed in the temperature range of 750 to 900℃ and the strain rate range of 0.01 to 10 s-1. The results indicate that the dynamic recrystallization temperature of the tested alloy is about 850 ℃ and the thermal activated energy Q is 427.937 kJ/mol, higher than those of the alloy with equiaxial grains. When ln Z<43, dynamic recrystallization always happens in the alloys. When\linebreak ln Z>51, dynamic recrystallization can not occur. When 43≦ln Z≦51, dynamic recrystallization may happen at 850 or 900 ℃, may not happen at 750 or 800 ℃, which can serve as the critical regions of the alloy for dynamic recrystallization. Such effect is probably ascribe to the difference in the dynamic recrystallization mechanisms of the continuous columnar grained materials and ordinary polycrystalline materials. It is observed that the dynamically recrystallized area in the sample has expanded when the strain rate increases. Dynamic recrystallization preferentially nucleates at grain boundary in the form of grain-boundary bulging. Twins form in the recrystallized grains and are evolved into grain belt by “twinning dynamic recrystallization”.
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