Статті КОМТ (ДМетІ)

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Patterning of Surfaces for Subsequent Roll Bonding in a Low-Oxygen Environment Using Deformable Mesh Inlays
(MDPI, 2023) Frolov, Yaroslav V.; Bobukh, Oleksandr S.; Samsonenko, Andrii A.; Nürnberger, Florian
ENG: Efficient roll bonding for the manufacturing of clad strips not only requires surface activation but also is improved by a surface patterning to reduce the initial contact area. This increases contact stresses and facilitates a joining without an increasing rolling force. Experiments to pattern surfaces with deformable inlays during cold rolling for a subsequent bonding in low-oxygen atmosphere were carried out using two types of rolling mills, two types of inlays and two types of assemblies. Digital twins of selected experiments were created by means of the FE simulation software QForm UK 10.2.4. The main set of rolling parameters, which play a significant role during formation of the pattern shape considering deformation of the patterning tool, were investigated. The pilot roll bonding of patterned components under vacuum conditions, provided using vacuum sealer bags, allowed for an experimental realization of this approach. The concept technological chain of roll bonding in a low-oxygen or oxygen-free environment comprises the following stages: roll patterning; surface activation and sealing of the strips in a vacuum bag; subsequent roll bonding of the prepared strips inside the protective bag. The difference between the shape of the pattern created and the initial shape of the mesh insert can be quantitatively described by the change of its angle. This difference reaches maximum values when smaller rolls are used with increased rolling reductions. This maximum value is limited by the springback of the deformed insert; the limit is reached more easily if the inlay is not positioned on the rolling plane.
Solid-State Diffusion and Intermetallic Phase Formation in Roll-Bonded Mg–Zn Composites with Kirigami-Patterned Inlay
(Wiley-VCH GmbH, Weinheim, 2026) Frolov, Yaroslav V.; Bobukh, Oleksandr S.; Klose, Christian; Nürnberger, Florian; Maier, Hans Jürgen
ENG: Solid-state diffusion and intermetallic phase formation were examined in roll-bonded magnesium alloy–zinc (Mg–Zn) composites that contain a kirigami-patterned magnesium alloy (ZX10) inlay. The kirigami-patterned inlay was embedded between two zinc sheets and roll-bonded at 310°C. Subsequent heat treatments at 318°C and 328°C promoted interfacial diffusion as well as the formation of intermetallic phases. The kirigami geometry of the inlay was employed as a process-level tool to impose spatially inhomogeneous deformation during roll bonding. This caused localized stress concentrations, driving the controlled transformation of the initial pattern within the deformation zone. It also prevented the thin inlay from failing prematurely and ensured its controlled distribution along the sample. Inhomogeneous strain distribution introduced three-dimensional diffusion pathways that activated bonding and initiated phase transformation. Flexural testing revealed a significant increase in mechanical strength compared to values calculated using the rule of mixtures. The maximum strength observed was 100 MPa for samples heat-treated at 318°C. Microstructural analyses showed a progression from adhesive bonding (group A) to uniform intermetallic layers (group B) and complex, multiphase regions containing eutectic, dendritic, and porous fractions (group C). Energy-dispersive X-ray spectroscopy confirmed zinc diffusion into the magnesium solid solution, indicating the onset of solid-state alloying. The combined effects of plastic deformation, thermal activation, and the kirigami-patterned Zn inlay resulted in Mg–Zn composites with enhanced interfacial integrity and a tailored phase composition. These composites offer a promising pathway for advanced material compounds to be used in biomedical and mechanical applications.