Mo 2Si Al MoSiAl2Eq

The aluminum melts (or forms an aluminum-silicon eutectic) prior to the initiation of the combustion synthesis reaction (Ref 27), as illustrated in the differential thermal analysis (DTA) scans of Fig. 8. The presence of this "extra" liquid acts as a rapid diffusion path, and as a consequence the initiation of reaction associated with the formation of the ternary compounds occurs at a lower temperature than the reaction to form binary MoSi2. The "extra" liquid phase can also be used to enhance densification during RHP. Similar results have been observed for silicon-modified aluminide compounds, such as Ti(Al,Si) (Ref 28).

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Fig. 8 Differential thermal analysis scans for reactive synthesis of Mo(Si,Al)2 from elemental molybdenum, silicon, and aluminum powders. Source: Ref 27. The addition of aluminum augments the liquid phase formation during reactive sintering.

Another example of the use of alloying to augment the liquid phase is the combustion synthesis of cermets. The reaction to form the TiC-Ni cermet is:

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