Effects of heat treatments on phase structure of electrodeposition aluminum coatings on different substrates

Effects of heat treatment on phase structure of electrodeposition aluminum coatings on different substrates was studied. The samples with dense aluminum coatings electrodeposited on Q235 mild steel, 1Cr17 ferrite stainless steel and 201 austenitic stainless steel from acid AlCl3-EMIC (2:1) room temperature molten salts was heat treated at 670°C. The interface microscopic analysis was carried by EDS, SEM and XRD. The results show that interdiffusion happens and the alloy layers form at the interface between aluminum coatings and the substrates after heat treated. Alloy layer grows like tongue to the substrate of Q235 which is flat on the substrate of 1Cr17 and 201 steel. The phases are FeAl and Fe2Al5phases, mainly Fe2Al5 on the internal and external alloy layers of Q235; but there are Fe2Al5 and FeAl3 phases containing Cr on the alloy layers of the 1Cr17 steel; there exists pure Al layer on the alloy layers of 201 steel heat treated after short time, the phases are mainly Fe2Al5 and FeAl3 phases containing Cr, Ni, Mn after heat treated for 30min, and there are a little FeAl2 and FeAl phases.