Identifying brittle-ductile transitions in intermetallic-metal hetero-interfaces

• Applicant: Dr. Anwesha Kanjilal
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566408913

This proposal determines the brittle-ductile transition (BDT) behavior of an intermetallic-metal hetero-interface, defined as the boundary between two different solid phases. To achieve this objective the dominant microscale deformation mechanisms will be analyzed under varying temperatures and strain rates. Hetero-interfaces significantly influence the strength and ductility of metallic alloys through local plasticity, decohesion, delamination, or fracture mechanisms. However, performing local mechanical measurements of isolated interfaces is challenging, due to which the temperature and strain rate dependence of interfacial deformation is unknown. As a result, BDTs for hetero-interfaces have not been identified yet. To investigate the BDT behavior of the intermetallic-metal hetero-interface, a novel micromechanical methodology is proposed which involves determination of the local interface strength at different temperatures and strain rates to unravel underlying deformation mechanisms, including thermal transitions. The BDT of a model interface, comprising of a CaMg2 Laves phase intermetallic layer deposited onto a Mg thin-film, will be identified by fabrication of micro-shear geometries by focused ion beam milling, followed by performing in situ tests inside a scanning electron microscope. This project will also provide fundamental insights into interface mechanics and the underlying deformation mechanisms, while also determining whether the interface BDT is a unique property, independent of the constituent phases. While CaMg2-Mg hetero-interfaces are important for the Mg alloys, the fundamental knowledge on interfacial deformation gained from this project will facilitate the design of robust engineering materials having improved interface properties.

• DFG Programme: Research Grants