Molybdenum titanium aluminides

Nickel aluminide (NiAl, Ni3AI), titanium aluminide (TiAl, Ti3AI), molybdenum disilicide (MoSi2)... 

Intermet allies Nickel aluminide (NiAl, NijAl) Titanium aluminide (TiAl, TijAl) Molybdenum disilicide (MoSi )... 

The selective oxidation of an alloy component, e.g., A1 or Si, requires the alumina or silica to be more stable than the oxides of the other components in the alloy. Figure 2.5 indicates this condition would be met for compounds such as nickel aluminides and molybdenum silicides. However, in the case of Nb- or Ti-base compounds the oxides of the base metal are nearly as stable as those of A1 or Si. This can result in conditions for which selective oxidation is impossible. This situation exists for titanium aluminides containing less than 50 at% A1 as illustrated in Figure 5.27. In this case a two-phase scale of intermixed AI2O3 and I1O2 is generally observed. It should be emphasized that the determination of which oxide is more stable must take into account the prevailing metal activities. 

Intermetallic compounds titanium aluminides [55-60], nickel aluminides [61-64], iron aluminides [65-68] and molybdenum silicides [69,70]. 

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