Microstructure and mechanical behavior of reaction hot-pressed titanium silicide and titanium silicide-based alloys and composites

Journal Article · Mon Jun 01 04:00:00 EDT 1998 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-998-0086-1· OSTI ID:634644

Mitra, R ^[1]

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1. Defence Metallurgical Research Lab., Hyderabad (India)

Titanium silicide (Ti{sub 5}Si{sub 3}) and its composites show promise for applications at temperatures higher than 1,000 C. Dense Ti{sub 5}Si{sub 3} was processed by reaction hot pressing of a TiH{sub 2}/Si powder mixture, which involved decomposition of TiH{sub 2} into Ti and H{sub 2} at around 800 C, a chemical reaction between Ti and liquid Si at 1,500 C forming Ti{sub 5}Si{sub 3} in situ, and densification under pressure. The use of fine TiH{sub 2} particles led to the formation of a relatively fine-grained microstructure with fewer microcracks and higher hardness and fracture toughness values than those expected for a coarse-grained Ti{sub 5}Si{sub 3}. The addition of 8 wt pct Al as an alloying element led to the formation of Al{sub 0.67}Si{sub 0.08}Ti{sub 0.25} and Al{sub 2}O{sub 3} in situ and a solid solution of Al in Ti{sub 5}Si{sub 3}. Both alloying with Al and the addition of TiC as a reinforcement phase improved the room-temperature fracture toughness. Fracture toughness measurements were performed by three-point bend testing of single-edge notch bend (SENB) specimens, as well as by indentation techniques using different models, and the data have been compared. The role of different operating toughening mechanisms such as crack deflection, bridging, branching, and energy dissipation through microcracking have been examine3d. The investigation has also shown that Ti{sub 5}Si{sub 3} maintains a high yield strength value up to 1,200 C.

• Sponsoring Organization: USDOE
• OSTI ID: 634644
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 6 Vol. 29; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
COMPOSITE MATERIALS
FRACTURE PROPERTIES
HARDNESS
MECHANICAL PROPERTIES
MICROSTRUCTURE
TITANIUM CARBIDES
TITANIUM SILICIDES