Influence of Al additions on the reactive synthesis of MoSi{sub 2}

Journal Article · Mon Apr 15 04:00:00 EDT 1996 · Scripta Materialia

DOI:https://doi.org/10.1016/1359-6462(95)00655-9· OSTI ID:230766

Alman, D E; Govier, R D ^[1]

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1. Bureau of Mines, Albany, OR (United States). Albany Research Center

The compound MoSi{sub 2} and MoSi{sub 2} matrix composites are being developed as potential elevated temperature structural materials for use in aggressive environments. Reactive synthesis has been used to produce prealloyed powders, dense monoliths, and in-situ composites. A few compounds, such as Ni{sub 3}Al and NiAl, can be consolidated to full density by reactive sintering without the application of external pressure. Densification in these cases is the result of capillary forces associated with the formation of a transient liquid phase that accompanies the reaction. The product of the reaction between Mo and Si powders during the formation of MoSi{sub 2} is, however, quite porous. In order to form dense monoliths, it is necessary for the process to be carried out under an applied pressure (e.g., Reactive Hot Pressing (RHP) or Reactive Hot Isostatic Pressing (RHIP)). Recently, US Bureau of Mines researchers, have discovered that alloying TiAl with Si is beneficial during reactive synthesis. The Si reacts with the Al to form a eutectic liquid prior to reacting with Ti to form a TiAl-Ti{sub 5}Si{sub 3} in-situ composite. This extra transient liquid formation aids densification, and apparently minimizes the swelling associated with the Kirkendall effect during the formation of TiAl. The current study was undertaken to determine if additions of Al to Mo and Si would have similar positive effect on the formation of the transient liquid phase during reactive synthesis of MoSi{sub 2} based alloys.

• OSTI ID: 230766
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 8 Vol. 34; ISSN 1359-6462; ISSN XZ503X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ADDITIONS
CHEMICAL REACTIONS
DENSITY
HOT PRESSING
IN-SITU PROCESSING
INTERMETALLIC COMPOUNDS
LIQUID METALS
MOLYBDENUM SILICIDES
POWDER METALLURGY
SYNTHESIS