Effect of Immersion Time and Temperature on the Interface Characteristics ‎of Pure Aluminium and Plain Carbon Steel

To reach an acceptable bimetallic composite product from two metals, interface characteristics needs to be investigated. In this work joining of commercial aluminium and a plain carbon steel and the formation and growth of intermetallic compounds at the interface was investigated. Steel rods were immersed into the pure aluminium melt at temperatures of 680, 720, 760 and 800 Celsius and kept for different times of 5, 10, 15 and 20 minutes, respectively and then were taken out and cooled in the air. After cross sectioning and sampling, the microstructure of interface between steel substrate and aluminium was studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Vickers hardness tests. The results showed that two intermetallic compounds, FeAl3 and Fe2Al5 are formed in the interface. Increasing the holding time and temperature changed the interface thickness and had no clear effects on the intermetallics types. Vickers hardness tests showed that the hardness of reaction interface was higher than aluminum and steel substrate due to presence of the above mentioned intermetallics. Kinetic of intermetallics formation are discussed.