Mg- Gd- Y- Zr合金单向压缩过程中动态再结晶行为研究

Dynamic recrystallization behavior during uni-directional compression process of Mg-Gd-Y-Zr alloy

利用电子背散射衍射技术(EBSD)研究了Mg-8.3Gd-2.6Y-0.4Zr合金在单向压缩中的动态再结晶行为。结果表明:在475℃单向压缩过程中,随着真应变的增加,变形晶粒被不断地拉长和破碎,而动态再结晶在比重提升的同时,其平均晶粒尺寸保持稳定(约为10μm);此外,在变形中小角度晶界不断转化成大角度晶界;而在ε=0.4的样品中,变形晶粒从心部到晶界处的取向差角不断增加,并导致再结晶晶粒在其晶界处出现。研究表明,合金再结晶的机制为连续动态再结晶。(0001)面极图显示,再结晶晶粒具有稳定的随机织构类型,并不随应变量的变化而发生改变。这种随机的织构是连续动态再结晶机制和稀土原子对晶界的钉扎共同作用的结果。

The dynamic recrystallization(DRX) behavior during uni-directional compression of Mg-8.3 Gd-2.6 Y-0.4 Zr alloy was investigated by the electron backscattering diffraction(EBSD). The results show that with the increasing of true strain during the uni-directional compression process at 475 ℃, the deformed grains are gradually elongated and broken up, while the fraction of DRXed grains persistently increases without changing their average grain size(about 10 μm). In addition, the low angle boundaries continuously transform into high angle boundaries during deformation, and in the sample with ε=0.4, the orientation difference angle of the deformed grains from the inner to the grain boundary continuously increases, causing the occurrence of recrystallized grains at the grain boundaries. Furthermore, the researches show that the mechanism of DRX is continuous DRX, and the(0001) plane pole figure reveals that the recrystallized grains have a stable random texture type and do not vary with the change of strain, which can be ascribed to the combined effect of the continuous DRX mechanism and the pinning effect of rare earth atoms on grain boundaries.