不同温度下AZ31镁合金绝热剪切变形局域化

为了了解镁合金在不同温度高应变率载荷作用下发生变形局域化的特点,进而揭示镁合金在高速冲击载荷作用下发生绝热剪切的特殊规律,采用分离式Hopkinson压杆对挤压态AZ31镁合金进行了常温及高温的高速冲击压缩试验,而后对不同温度冲击后的试样通过光学显微镜、扫描电镜和透射电镜进行变形机制的分析.结果表明:常温下试样在受到剪切力后,在剪切区的裂纹周围产生了大量的孪晶;高温下试样的剪切区内产生了明显的绝热剪切带,并且在剪切带周围发现了大量平行的孪晶.在TEM下观察到剪切带内为等轴晶晶粒,在剪切区内发生了动态再结晶过程.

Adiabatic shear deformation localization of AZ31 magnesium alloy at different temperatures

In order to understand the characteristics of deformation localization of magnesium alloys under high strain rate at different temperatures and reveal the special rule of adiabatic shearing of magnesium alloy under high speed impact load, the high-speed impact compression tests at both room and high temperatures were conducted with the split Hopkinson pressure bar for extruded AZ31 magnesium alloy. The optical microscope, scanning electron microscope and transmission electron microscope were utilized to analyze the deformation mechanism of the samples subjected to the impact tests. The results show that at room temperature, a large amount of twins form around the cracks in the shear zone due to the effect of shear force. At the high temperature, the obvious adiabatic shear band appears in the shear zone of samples, and a great amount of parallel twins form around the adiabatic shear band. The results of TEM observation show that the grains inside the shear band are isometric ones, and the dynamic recrystallization occurs in the shear zone.