EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Currently, aircraft and aerospace industries are focused on developing new and more capable ceramic matrix composites (MMCs and CMCs) reinforced by high-strength continuous fibers. However, limitations exist: costly manufacturing processes, difficulties in producing/assembling large and complex CMCs shapes, integration with dissimilar materials (i.e., metals, ceramics or other composites) and fibers degradation during fabrication processes and in service, mainly at high temperature. Indeed, Cf and SiCf show the tendency to be oxidized/degraded (by releasing CO-SiO) if processed at T above 400°C and 1200°C under oxidizing atmospheres, respectively. Reliable densification and joining of CMCs by liquid assisted processes are crucial for preserving the CMC thermomechanical properties and for saving weight. Both densification and joining reliability are ensured by the microstructures resulting from the interaction phenomena occurring at the metal/fiber interfaces.
Such limitations are forcing to improve the existing options or to explore new materials. High entropy alloys (HEA) are proved to be a new initiative in today era in the field of materials science and engineering. Indeed, high entropy materials (HEM) show outstanding mechanical properties [1,2,3]. Exhibiting large ductility, key requirement in structural applications in the area of transportation and energy fields, the high demand for HE-alloys (HEA) is well justified.
In this work, a theoretical-experimental method has been applied for the feasibility study of using successfully HEA alloys as fillers, brazers and coatings for CMCs. Specifically, the FCC-CoCrFeMnNi alloy was selected as case study to densify and join CMCs based on Cf and the results will be presented as well as the wettability of SiC and C by the selected HEA and related interfacial phenomena.
[1] J.W. Yeh, et al. Adv. Eng. Mater. 6 (5) (2004) 299– 303
[2] D.B. Miracle, et al. Acta Mater. 122 (2017) 488-455
[3] T. E. Whitfield, et al. J. Alloys Compd. 857 (2021) 157583.