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研究了粗晶Mg-3Gd-1Zn合金在723~823 K,应变速率0.100~0.001 s-1条件下单轴压缩变形过程中的动态再结晶行为。研究结果表明,其热压缩曲线为典型的动态再结晶型,峰值流变应力和稳态流变应力随温度的升高而减小,随应变速率的增大而增大;在该实验温度范围内其变形激活能约为140 kJ.mol-1;再结晶晶粒尺寸lnd与lnZ参数偏离线性关系,且变形温度对再结晶晶粒尺寸的影响比应变速率更大。利用金相和电子背散射技术(EBSD)对773 K,0.010 s-1条件下压缩不同变形量的Mg-3Gd-1Zn合金进行了组织表征,发现其动态再结晶大都发生在孪晶界及其与原始晶界的交叉处,主要为孪生诱发动态再结晶形核(TDRX)机制。再结晶形核初期形状不规则,晶界倾向于呈直角,随着应变量的增大,由于晶界的局部迁移,再结晶晶粒逐渐转变为稳定的等轴晶。
The dynamic recrystallization behavior of coarse-grained Mg-3Gd-1Zn alloy during uniaxial compression at 723-823 K and strain rates of 0.100-0.001 s-1 was studied. The results show that the hot compression curve is a typical dynamic recrystallization, the peak flow stress and steady flow stress decrease with the increase of temperature, and increase with the increase of strain rate. Under the experimental temperature range The deformation activation energy is about 140 kJ · mol-1. The recrystallization grain size lnd and lnZ deviate from the linear relationship, and the influence of deformation temperature on recrystallization grain size is larger than the strain rate. The microstructures of Mg-3Gd-1Zn alloys with different deformations under the conditions of 773 K and 0.010 s-1 were characterized by means of metallographic and electron backscattering (EBSD). It was found that the dynamic recrystallization mostly occurred in the twin boundaries and its At the intersection with the original grain boundaries, the twin-induced dynamic recrystallization nucleation (TDRX) mechanism is mainly involved. The initial shape of recrystallization nucleation is irregular and the grain boundaries tend to be at right angles. With the increase of strain, the recrystallized grains gradually transform into stable equiaxed grains due to the local migration of grain boundaries.