To understand the formation and growth of plasma electrolytic oxidation (PEO) coatings in presence of different secondary phases in a substrate, PEO treatment was carried out on AlSi9Cu3 alloy at different treatment times ranging from 15 s to 480 s. The coating formation and evolution process was traced by surface and cross-sectional observation of the layers on the different phases of the alloy. The results demonstrated a sequential involvement of the different phases in the plasma discharges: firstly, discharges start on the α-Al matrix, then on the intermetallic Al₂Cu and β-Al₅FeSi phases at the same time and finally on the eutectic Si. The presence of intermetallic Al₂Cu remarkably affects the initial dissolution, the deposition of conversion products and the ignition of discharges at the early stages of processing. Eutectic Si in the substrate exhibits the highest electrochemical stability at all stages and contributes in the beginning to a distinct coating morphology eventually. The resultant PEO coating tends to be uniform if processing times are longer and a double-layer structure appears in the coating.

为了了解在基材中存在不同次级相的情况下等离子体电解氧化（PEO）涂层的形成和生长，对AlSi9Cu3合金在15 s至480 s的不同处理时间进行了PEO处理。通过在合金的不同相上的层的表面和横截面观察来追踪涂层的形成和演变过程。结果表明不同相的在等离子体放电顺序参与：首先，放电在所述α-Al基体开始，然后在金属间的Al ₂ Cu和β-Al系₅同时硅铁阶段和最后在共晶Si 。金属间Al ₂的存在Cu在加工的早期阶段显着影响初始溶解，转化产物的沉积和放电的点燃。基材中的共晶硅在所有阶段均表现出最高的电化学稳定性，并在开始时最终有助于形成独特的涂层形态。如果加工时间较长并且涂层中出现双层结构，则所得的PEO涂层趋于均匀。