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Molybdenum/Niobium Disilicide Multilayers Fabricated by Tape Casting: Microstructure, Mechanical Properties and
Dreidy Mercedes Vásquez1,2, Elisa Padovano1, Claudio Badini1
1Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
Materials (Basel, Switzerland)
|May 4, 2026
Summary
Adding niobium silicide (NbSi2) to molybdenum disilicide (MoSi2) composites prevents low-temperature pest oxidation. This modification also eliminates silica inclusions, improving toughness in these high-temperature materials.
Area of Science:
- Materials Science
- High-Temperature Materials
- Ceramics
Background:
- Molybdenum disilicide (MoSi2)-based intermetallics possess desirable properties for high-temperature applications, including moderate density, high melting point, and excellent oxidation resistance.
- However, pure MoSi2 is susceptible to pest oxidation at low temperatures, limiting its practical use.
- The presence of silica inclusions can also negatively impact material toughness.
Purpose of the Study:
- To fabricate MoSi2-based composites with enhanced properties, specifically targeting the prevention of low-temperature pest oxidation.
- To investigate the effect of niobium silicide (NbSi2) addition on the phase composition, microstructure, mechanical properties, and oxidation resistance of MoSi2.
- To understand the mechanisms behind the elimination of silica inclusions and the formation of secondary phases.
Main Methods:
- Multi-layered MoSi2-based structures were fabricated using tape casting and pressureless sintering.
- Composites containing up to 20 wt.% NbSi2 were produced.
- Characterization involved analysis of phase composition, microstructure, mechanical properties, and oxidation resistance.
Main Results:
- The addition of limited amounts of NbSi2 effectively prevented the pest oxidation phenomenon in MoSi2.
- Silica inclusions, detrimental to toughness, were eliminated in the sintered silicides.
- The elimination of silica was attributed to a reducing atmosphere and carbonaceous residues during binder burnout.
- Phase analysis indicated the formation of secondary phases, including silicon carbide.
Conclusions:
- NbSi2 addition is a viable strategy to enhance the high-temperature performance of MoSi2 by mitigating pest oxidation.
- The developed processing route successfully eliminated detrimental silica inclusions, improving the toughness of the composites.
- The resulting MoSi2-NbSi2 composites show promise for demanding high-temperature applications requiring both oxidation resistance and mechanical integrity.
