Intermetallic Phases Identification and Diffusion Simulation in Twin-Roll Cast Al-Fe Clad Sheet

Aluminium steel clad materials have high potential for industrial applications. Their mechanical properties are governed by an intermetallic layer, which forms upon heat treatment at the Al-Fe interface. Transmission electron microscopy was employed to identify the phases present at the interface by selective area electron diffraction and energy dispersive spectroscopy. Three phases were identified: orthorhombic Al5Fe2, monoclinic Al13Fe4 and cubic Al19Fe4MnSi2. An effective interdiffusion coefficient dependent on concentration was determined according to the Boltzmann–Matano method. The highest value of the interdiffusion coefficient was reached at the composition of the intermetallic phases. Afterwards, the process of diffusion considering the evaluated interdiffusion coefficient was simulated using the finite element method. Results of the simulations revealed that growth of the intermetallic phases proceeds preferentially in the direction of aluminium.

Hot Rolling of the Twin-Roll Cast and Homogenized Mg-6.8Y-2.5Zn (WZ73) Magnesium Alloy Containing LPSO Structures

In this study, hot rolling trials were conducted on a twin-roll cast and homogenized magnesium alloy Mg-6.8Y-2.5Zn (WZ73). The WZ73 contains long period stacking ordered (LPSO) structures due to the ratio of Y and Zn content. Microstructural and texture evolution depending on the different strain and strain rates were investigated, and the resulting mechanical properties were also considered. Therefore, samples were quenched in water directly after hot rolling. The results revealed that the rolling parameters significantly influence dynamic recrystallization (DRX), while continuous and twin-induced dynamic recrystallization are assumed to be the main DRX mechanisms. It was also found that high strains and strain rates are required to proceed the DRX. The resulting textures revealed that the non-basal slip of <a>-dislocations and <c+a>-dislocations is activated during hot rolling. Hot rolling results in increased strength and ductility compared to the initial twin-roll cast and homogenized state.