Exploring a new class of interpenetrating-phase metal-metal composites synthesised by liquid metal dealloying

• Applicants: Dr.-Ing. Ilya Okulov; Professorin Dr.-Ing. Jana Wilmers
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 577003923

This research project focuses on exploring a new class of metal-metal composites synthesised by liquid metal dealloying. These novel composites possess a unique, scalable microstructure of interpenetrating immiscible metal phases at the nano- or microscale, which results in characteristic and unusual combinations of mechanical properties such as high yield strength and low elastic modulus that cannot be found in other synthetic materials. The mechanisms behind the unusual mechanical properties of interpenetrating-phase composites, however, are not yet understood and will be systematic investigated in this project. The hypotheses and objectives of the project are provided below. Hypotheses: 1. Anomalously low effective elastic modulus of the 3D interconnected composites consisting of immiscible metals and synthesised by liquid metal dealloying originates from, a. Interfacial sliding due to the weakened interphase; b. Hidden local plastic deformation of one component/phase; c. Localised porosity in the interphase of immiscible components/phases; d. A combination of the above; 2. Effective elastic modulus of the composites is size-dependent. Objectives: • Investigation of the effect of coefficient of thermal expansion of the constituent phases on the internal stresses and the formation of interfacial porosity in the interpenetrating-phase composites and analysis of their effect on mechanical behaviour; • Investigation of the size effect of ligaments on mechanical behaviour of the interpenetrating-phase composites; • Investigation of the effect of mechanical properties of composing phases (e.g. yield strength) on the mechanical behaviour of the interpenetrating-phase composites • Development of reliable continuum mechanical models for the interfacial sliding and numerical investigation of the effect of interface sliding and localised porosity on the effective mechanical behaviour the interpenetrating-phase composites; • Continuum mechanical modelling and simulation of localised plasticity in the ligaments and the interphase region to investigate and predict magnitude and microstructural dependencies of this effect; • Unification of experimental and numerical results to identify the mechanisms active in the metal-metal composites and their possible interactions. To investigate individual effects of the microstructure and the different phase properties on the effective behaviour, experimental analysis and numerical modelling on the structural feature’s length scale will be employed jointly. As multiple mechanisms may be active at the same time and contribute to the effective properties, the experiments are designed to minimize these effects and the numerical simulations are vital in separating and quantifying these contributions.

• DFG Programme: Research Grants
• International Connection: Japan
• Cooperation Partner: Professor Hidemi Kato, Ph.D.