Microstructural Evolution during Continuous Heating of Multilayered Al/Fe Metallic Composite Processed by Accumulative Roll Bonding

Despite the large number of studies on the development of multilayered composites using accumulative roll bonding method (ARB), there are not enough available details concerning the effect of the temperature variation on the constituent layer microstructure and the nature and kinetics of the developed intermetallic compounds. The present work aims to process an Al/IF steel multilayered composite using ARB and to understand the effect of non-isothermal heating on its structural evolution. The elaborated material is characterized by using thermal Differential Dilatometry (DD), Scanning Electronic Microscopy (SEM) and x-ray Diffraction (XRD). The progress of the ARB leads to the dispersion of the Fe layers between the Al layers and does not lead to the formation of diffusion layer. The continuous heating leads, for temperature lower than 330 °C, to the occurrence of the recovery reaction in the Al layers, which produces a big contraction and causes a partial softening of the material. The formation of the intermetallic compound Al₅Fe₂ seems to occur at higher temperatures and leads to a significant expansion of the material. This effect is explained by the increase in the atomic specific volume.