Development of high-performance Mo-based alloys employing new strengthening and oxidation resistance concepts

• Applicants: Professorin Dr.-Ing. Bronislava Gorr; Dr. Ievgen Solodkyi
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins ; Synthesis and Properties of Functional Materials
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564643118

For the last few decades, extensive efforts have been made to explore ultrahigh temperature structural Mo-based materials that may be used in harsh working conditions at temperatures above 1100 °C. Despite numerous endeavours, up to now, there is no high-temperature Mo-based material that meets all the most relevant requirements such as creep resistance at elevated temperatures, oxidation resistance, and a certain degree of ductility at room temperature. In this project, we propose to develop new Mo-based materials by combining the vast knowledge generated while exploring the “conventional” Mo-based alloys such as Mo-8B-9Si as well as Refractory High Entropy Alloys (RHEA) with high Mo concentrations, e.g. equiatomic Ta-Mo-Cr-Ti-Al alloy. The design of new high-performance materials will be realized on the alloy system Mo-Ta-Cr-Ti. The room temperature plasticity of novel Mo-based alloys developed in this project will be provided – analogously to conventional Mo-based alloys – by the ductile continuous body-centered cubic (bcc) Mo-rich matrix. The two strengthening mechanisms, i.e. solid solution strengthening (SSS) and precipitation strengthening (PS) will be utilized to guarantee the high creep resistance. The SSS will be implemented by alloying with Ta and Ti which readily dissolve in the bcc matrix. In order to find the chemical composition accompanied with the maximum SSS effect, we proposed to perform modelling of screw dislocation-controlled solid solution strengthening using the Maresca–Curtin models. In contrast to conventional Mo-based alloys, the PS will be realized by the Laves phase precipitates. To quantitatively describe the mechanism of the Laves phase formation and to estimate the role of this phase on the creep resistance and room temperature plasticity, alloys with different phase fraction of the Laves phase will first be thermodynamically modelled and subsequently experimentally investigated. Due to the non-trivial approach to producing the alloy, namely powder technology, which involves in-situ alloying under spark plasma sintering (SPS) conditions, we will be able to avoid the formation of the Laves phase along the boundaries of large grains, as in the case of melting technology. The preliminary studies successfully confirmed this assumption. The next novelty represents a new concept of oxidation resistance which will be ensured by the rarely encountered Cr-Ta-based complex oxides that exhibit a very high degree of protectiveness on recently developed RHEA. The theoretical assessments will be supported and verified by extensive experimental investigations with respect microstructural studies, characterization of mechanical properties and oxidation behaviour.

• DFG Programme: Research Grants
• Co-Investigator: Professorin Dr.-Ing. Manja Krüger