Cu的添加对X80钢热浸法渗铝层组织的影响

通过在热浸镀铝熔池中添加Cu元素，改善X80钢热浸法渗铝层的组织。在不同的温度下进行扩散退火试验，利用扫描电镜和X射线衍射仪研究退火温度和铜元素对渗层组织的作用机理。采用Smile View软件对渗层厚度进行测量。结果表明，在热浸法渗铝时，Cu的添加可以使合金层/X80钢基体界面间的舌齿状形态缩小，使得界面间反应更均匀。当Cu的添加量为1%(质量分数)时，脆性的Fe₂Al₅合金层的厚度最小。随着扩散退火温度的升高，Cu添加量为1%的试样渗层的界面均匀性增加；扩散退火温度≥600℃时，渗层中开始出现极薄的FeAl相层；扩散退火温度≥650℃时，自由层消失，渗层中出现均匀的FeAl层且渗层外侧出现孔洞；扩散退火温度为700℃时，FeAl层中部出现孔洞带，且渗层外侧出现大孔洞。在热浸镀铝熔池中加入1%Cu元素可以使扩散退火过程中Al原子和Fe原子间的迁移速率差值减小，进而降低Al原子和Fe原子间的浓度梯度。原子间浓度梯度的降低，使得界面间反应更均匀，从而避免渗层中孔洞的出现。

Effect of Cu addition on microstructure of hot dipping aluminized layer on X80 steel

Microstructure of hot dipping aluminized layer on X80 steel was improved by adding Cu element to the hot dipping aluminizing bath. Diffusion annealing experiments were carried out at different temperatures to investigate the affecting mechanisms of annealing temperature and copper element on microstructure of the aluminized layer by means of scanning electron microscope and X-ray diffractometer. Smile View software was used to measure the thickness of aluminized layer. The results show that during hot dipping aluminizing, the addition of Cu reduces the tongue-and-groove morphology between the alloy layer/X80 steel substrate interface to make the interfacial reaction more uniform. The thickness of the brittle Fe₂Al₅ alloy layer is minimum when the Cu content is 1% (mass fraction). With the increase of diffusion annealing temperature, the interface uniformity of the specimen with 1%Cu addition increases. When the diffusion annealing temperature is ≥600 ℃, a very thin FeAl phase layer begins to appear in the diffusion layer. When the diffusion annealing temperature is ≥650 ℃, the free layer disappears, the uniform FeAl layer appears in the diffusion layer and the holes appear outside the diffusion layer. When the diffusion annealing temperature is 700 ℃, the middle of the FeAl layer has a hole zone, and the outside of the diffusion layer has large holes. The addition of 1%Cu to the hot dipping aluminizing bath reduces the difference of migration velocities between Al and Fe atoms during diffusion annealing, thereby reducing the concentration gradient between Al and Fe atoms, which results in a more homogeneous interfacial reaction, thus avoiding the appearance of holes in the infiltrated layer.