表面纳米化对AZ91D镁合金渗铝行为的影响

The Influence of Surface Nanocrystallization on The Aluminizing Behavior of AZ91D Magnesium Alloy

摘要:

镁合金表面渗铝是提高耐蚀性的一种有效方法。本研究将表面纳米化作为渗铝的预处理过程。采用高能喷丸对AZ91D镁合金进行表面纳米化处理,然后真空铝扩散得到渗铝层。用透射电镜(TEM)和扫描电镜(SEM)观察了渗铝层的形貌。结果表明,在AZ91D镁合金高能喷丸后获得了100 nm的晶粒尺寸。在高能喷丸之后,渗铝层的深度比没有高能喷丸的渗铝层厚。在440℃下扩散12小时后,渗铝层的深度增加到70m m。采用电化学方法对AZ91D镁合金的耐腐蚀性能进行了表征。结果表明,渗铝层明显降低了AZ91D镁合金的腐蚀速率。因此,高能喷丸强化有利于镁合金表面渗铝,提高镁合金的耐蚀性。

Abstract:

Surface aluminizing for magnesium alloy is an effective method to improve corrosion resistance. This research introduces surface nanocrystallization as the pre-process of aluminizing. AZ91D magnesium alloy is processed by high energy shot peening (HESP) to achieve surface nanocrystallization, and then vacuum solid state aluminum diffusion to obtain aluminized layer. The morphology of the aluminized layer is observed with Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). It shows that the surface of the nanocrystalline grain size of 100 nm was obtained after HESP of AZ91D magnesium alloy. After HESP, the depth of the aluminized layer is thicker than that of the aluminized layer without HESP. After diffusion of 12 hours under the temperature of 440 ℃, the depth of aluminized layer increases to 70 mm. The corrosion resistance of AZ91D magnesium alloys are characterized by electrochemical method. It shows that the aluminized layer obviously decreases the corrosion rate of AZ91D magnesium alloy. Therefore, high energy shot peening(HESP)was beneficial to surface aluminizing and can improve the corrosion resistance of magnesium alloy.