한국주조공학회

Fusion bonding of cast iron and Al alloy is an effective way to improve the properties such as low inertia, high efficiency and corrosion resistance in machinery parts. In case of fusion bonding, intermetallic compound layers are formed at the interface between cast iron and Al alloy interface. It is important to control the intermetallic compound layers for improving bonding strength. The formation behavior of intermetallic compound layer by heat treatment has been investigated. Heat treatment was performed at temperature from 600oC to 800oC with 100oC interval for an hour to investigate the phase transformation during heat treatment. Heat treated specimens were analyzed by using FE-SEM, EPMA and EDS. The EPMA/WDS results revealed that various phases were formed at the interface, which exhibited 4 distinct intermetallic compound layers such as τ6-Al4.5FeSi, τ2-Al3FeSi, τ11-Al5Fe2Si and η-Al5Fe2. Also, fine precipitation of τ1 Al2Fe3Si3 phase was formed between τ11 and η layer. The phase fraction in intermetallic compound layer was changed by heat treatment temperature. At 600oC, intermetallic compound layer of τ6 phase was mainly formed with increasing heat treatment time. With increasing heat treatment temperature to 800oC, however, τ2 phase was mainly distributed in intermetallic compound layer. τ1 phase was remarkably decreased with increasing heat treatment time and temperature.

Intermetallics, Bonding, Phase transformation, Cast iron, Al alloy, Heat treatment.