In situ synchrotron characterization of mechanically activated self-propagating high-temperature synthesis applied in Mo-Si system

Journal Article · Fri May 28 04:00:00 EDT 1999 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(99)00084-1· OSTI ID:357928

Gras, C; Charlot, F; Gaffet, E ^[1]; Bernard, F; Niepce, J C ^[2]

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1. CNRS, Belfort (France)
2. Univ. of Burgundy, Dijon (France)

An original experiment was designed to monitor structural and thermal evolutions during the MASHS (Mechanically Activated Self-propagating High-temperature Synthesis) process in the Mo-Si system. Time-Resolved X-Ray Diffraction (TRXRD) coupled with an infrared imaging technique was performed to study, in situ, the formation of the {alpha}-MoSi{sub 2} phase in the combustion front. Despite a temporal resolution of 50 ms between two consecutive diffractograms, no intermediate phase was observed during the passage of the combustion front. The only reaction responsible for the self-sustentation is Mo + 2Si {r_arrow} MoSi{sub 2} in the primary zone inside the combustion wave. The mechanical activation was found to influence Self-propagation High-temperature Synthesis (SHS) parameters such as the propagation front velocity (> 13 mm s), the maximal combustion temperature and the local thermal gradient. After the MASHS process, the {alpha}-MoSi{sub 2} compound is nanostructured (D{sub MoSi{sub 2}} = 88 nm) and some explanations are expressed in order to understand why the nanostructure of the as-milled powders can be maintained during the combustion reaction.

• OSTI ID: 357928
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMBUSTION WAVES
MICROSTRUCTURE
MILLING
MOLYBDENUM SILICIDES
POWDERS
SYNTHESIS
VELOCITY
X-RAY DIFFRACTION