脉冲电流对AZ31镁合金显微组织及拉伸变形行为的影响

Effect of Pulse Current on Microstructure and Tensile Deformation Behaviorof AZ31 Magnesium Alloy

摘要:

为改善镁合金塑性变形能力,在AZ31镁合金的拉伸变形中引入高密度脉冲电流,研究了脉冲电流对合金显微组织及拉伸变形行为的影响规律,并探讨了其机理。结果表明,与未加脉冲电流拉伸相比,施加脉冲电流的AZ31镁合金的变形抗力显著降低,并且随脉冲电流密度的提高,其变形抗力下降的幅度增大。施加脉冲电流的合金在拉伸过程中发生了明显的动态再结晶,再结晶晶粒细小均匀,从而降低了合金的变形抗力。这是由于脉冲电流可以提高原子通量、促进原子扩散、加快小角亚晶向大角度亚晶转变,从而促进了合金的动态再结晶。另一方面,脉冲电流产生的电效应能够改变位错的激活能,使其容易克服滑移面上的障碍,增加位错可动性,从而提高合金塑性变形能力。

Abstract:

In order to improve the plastic deformation capacity of magnesium alloy, tensile tests of AZ31 magnesium alloy accompanied with high intensity pulse current were carried out. The effects of pulse current on microstructure and tensile deformation behavior of the alloy were investigated and the mechanisms were examined as well. The results show that the deformation resistance of AZ31 magnesium alloy with pulse current greatly decreases compared with that without pulse current, and the extent of decline raises as current density increases. The dynamic recrystallization (DRX) occurs in the alloy with pulse current during the tensile testing, and obtain fine recrystallized structure, which can bring down the deformation resistance. The rapid recrystallization behavior is based on the enhancement of atomic diffusion and acceleration of the grain boundary transformation from small angle to large angle resulting from pulse current. On the other hand, the increasing of the plastic deforming ability of the alloy was attributed to the electric effect of the pulse current, which can change the activation energy of dislocations and promote the mobility of dislocations.