Open-pore cellular Si structures are manufactured by investment casting and, subsequently, infiltrated with molten Mg(-Sn), representing the initial state for a formation of the intermetallic compound Mg 2 Si 1-x Sn x . The processing parameters which govern the evolution of microstructure after the infiltration process are studied in the alloy systems Mg-Si and Mg-Si-Sn. The resulting microstructures are analyzed using SEM and EDS. It is found that an initial diffusion layer is already formed after infiltration. Its thickness can slightly be increased by raising the infiltration temperature of the Mg(-Sn) melt. A variation in mold temperature does not show a noticeable impact. The comparison of the diffusion layer formed in the systems Mg-Si and Mg-Si-Sn showed that a lower Sn content resulted in thicker layers.
The present work explores the growing behavior of the intermetallic layer in the Mg-Si system. Following achievements have been obtained in our investigation: (i) A complete wetting concept is proposed for the lateral spreading of the intermetallic layer. (ii) In contrast to the stoichiometric property for the intermetallic phase in the phase diagram, the authors show that concentration gradients are able to be established in the kinetic process. (iii) Contrary to the reported growth behavior, d / t 0.25-0.5 in other intermetallics, the authors find a transition from d / ffiffi t p to d / t with an increase of the temperature, where d is the thickness of the intermetallic layer and t is the time.
Herein, a holistic investigation of the process chain of polymer foam template manufacturing for the investment casting of open‐cell metal foams and their evaluation in terms of mechanical response under compressive loading is presented. Polymer foam templates are manufactured using sucrose beads as spaceholders with a body‐centred cubic (bcc) stacking and epoxy resin as matrix material. These templates are used in a modified investment casting process to produce commercial pure open‐cell Al foams (AA 1050 A). The materials used for the polymer foam templates are suitable for the template production and the use in investment casting. The structure of the template can be exactly reproduced by investment casting and no byproducts from the pyrolysis step can be detected within the molds or the Al foams. The mechanical properties under compressive loading are comparable with high‐strength Al‐alloy foams with a structure factor of C1 of 0.60. The characteristic plastic deformation is dominated by buckling, showing a local plastic failure of the struts within cell layers. Due to a high node‐to‐strut thickness ratio, neither small defects in the microstructure nor stacking errors of the template impact this deformation behavior.
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