Identification of the intermetallic compound layer formed at the interface of roll-bonded aluminum-clad steel by thermal annealing

Aluminum clad steel (ACS) is an excellent layered composite material. An intensive investigation into roll-bonded ACS was carried out to identify the intermetallic compound (IMC) formed at the interface between the aluminum (Al) and the steel. A series of analyzing methods was applied to the IMC layer formed at the interface during annealing at 540 °C for 16 h. An electron probe micro-analyzer (EPMA) measured a value of 28.5 atomic percent for the Fe in the IMC layer, which coincided with the Fe2Al5 phase. An analysis of the X-ray diffraction pattern for the IMC layer in the ACS materials showed a very strong peak for the (002) plane of Fe2Al5. Vickers microhardness testing of the IMC layer revealed a very high value (1,110 Hv). The results of EPMA, XRD and microhardness values verified that the IMC layer in the sample that had been annealed at 540 °C for 16 h was the Fe2Al5 phase.