Oxidation of Ti-AI intermetallic compounds

1 Advantages and potential applications of TiAI-base alloys 

There are a few intermetallic compounds in the binary Ti-Al system. TiAl and its alloys have been studied much more than the others. Therefore, the main part of this chapter is devoted to TiAl, and issues regarding Ti3Al and TiAl3 will be dealt with to a lesser degree. 

Ti alloys and Ni-base superalloys are applicable to TiAl alloys. This will bring about great economic merit at practical production stages. 

However, the main drawbacks of TiAl alloys are insufficient room-temperature ductility and poor oxidation resistance above about 1000 K. When these drawbacks are overcome, TiAl aUoys will find much wider areas of application. This chapter mainly deals with the oxidation behaviour of TiAl alloys and measures for improving their oxidation resistance. Details of other properties are excluded, because they are beyond the scope of this chapter. 

7 (a) A turbocharger wheel made of a TiAl alloy for a passenger car (b) centre an engine valve made of a TiAl-Mn alloy by HIP right after a long time of oxidation left a conventional steel valve. 

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Beryllia. See beryllium oxide. Beryllides. A group of intermetallic compounds of potential interest as special ceramics. Cell dimensions and types of structure have been reported for the beryllides of Ti, V, Cr, Zr, Nb, Mo, Hf and Ta (A. Zalkin el ai, Acta Cryst., 14, 63,1961). 

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