利用扫描电镜和能谱分析手段研究了铝池中的硅对热浸镀铝层在真空高温扩散处理过程中的显微组织演变的影响。确定了扩散层的组成相,研究了镀层的生长动力学,讨论了扩散层空洞带的形成机理。研究表明,铝池中的硅能减少热浸镀铝层的厚度。在同样的扩散条件下硅的添加抑制了Fe2Al5的生长,促进了FeAl和富铝α-Fe层的生长。扩散处理时从含硅的Fe2Al5中容易析出τ1-（Al,Si）5Fe3相或FeAl相。硅的加入使得FeAl层和富铝α-Fe层间的空洞或晶间裂纹易于早期出现,但随着扩散时间的延长,又逐渐减小或消失。空洞的形成与消失与硅在FeAl层中的富聚有关。由于Fe2Al5相与其中析出的τ1-（Al,Si）5Fe3相发生包共晶反应,即：τ1＋Fe2Al5L＋FeAl,形成了不连续的外侧FeAl层。
Effect of silicon in aluminum bath on microstructure evolution of hot-dipping aluminum coating after diffusion treatment in vacuum was investigated by means of scanning electron microscopy（SEM） and energy dispersive spectrometer（EDS）.The Fe-Al and Fe-Al-Si intermetallic compounds in the coatings were identified.Growth dynamics of the coatings was studied.The formation mechanism of voids between FeAl and α-Fe layers were discussed.The results show that when silicon is added in aluminum bath,the hot-dipping aluminum coatings become thinner.The diffusion treatment suppresses the formation of Fe2Al5 layer and is favorable for the formation of FeAl and α-Fe layers.τ1-（Al,Si）5Fe3 or FeAl phase tends to precipitate in the Si-containg Fe2Al5 layer.The voids and intergranular cracks between FeAl layer and the Al-rich α-Fe layer are easily to form Si-containg in the coatings,but they become smaller and disappear with prolongation of the diffusion time.The formation and disappearance of voids are related with silicon enrichment in the FeAl layer.The discontinuous outer FeAl layer forms by quasi-peritectic reaction（τ1＋ Fe2Al5 L＋FeAl）.
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