Stoichiometry and Texture Evolution of Individual Layers during Accumulative Roll Bonding of Al-Mg Laminated Composites

Six cycles of ARB at three elevated temperatures (400, 450, and 500 ?) were applied on Al/Mg laminated metallic composites. Samples were studied by microscopy, spectroscopy, and x-ray diffraction to investigate the effect of temperature on microstructures, second phases, and preferred crystallographic orientations. Stoichiometry analysis indicated the formation of non-equilibrium intermetallic phases at the Al/Mg interface. The thickness of the intermetallic layer increased in consecutive passes and by increasing process temperature. Annealing moved the composition toward predicted thermodynamically stable phases by absorbing Al and rejecting excess Mg. EDS examination showed the formation of Al2Mg and Al30Mg23 phases in addition to the previously reported Al12Mg17 and Al3Mg2. XRD results indicated that the preferred crystallographic orientation of the Al layer deviates from the expected plain-strain rolling texture. At the same time, for the Mg layer, the hexagonal c-axis remained parallel to the applied rolling force direction. The most uniform crack-free structure has been formed at 450 ?.

Automated summary

The effect of temperature on microstructures, second phases, and preferred crystallographic orientations of Al/Mg laminated metallic composites was studied. Non-equilibrium intermetallic phases were formed at the Al/Mg interface. The thickness of the intermetallic layer increased with consecutive passes and higher process temperature. Annealing shifted the composition towards thermodynamically stable phases. XRD results showed deviation from expected crystallographic orientation in the Al layer and alignment with the rolling force direction in the Mg layer. The most uniform and crack-free structure was formed at 450℃.