EFFECT OF CARBON AND NITROGEN ON MECHANICAL-PROPERTIES OF TIAL ALLOYS

The effect of carbon and nitrogen on mechanical properties of single and dual phase gamma-TiAl alloys was studied in tensile tests at room temperature as functions of content of interstitial elements such as carbon and nitrogen, titanium/aluminum compositional ratio and grain size. The fracture strain in stoichiometric and aluminum-rich TiAl alloys annealed at 1 423 K was improved from nearly zero plastic strain to 0.6-0.8% plastic strain by the addition of 0.3-0.6 at% carbon. In titanium-rich TiAl alloys annealed at 1423 K and all of titanium-rich, stoichiometric and aluminum-rich TiAl alloys annealed at 1 573 K, tensile fracture strain was decreased by the addition of carbon and nitrogen. Volume of a unit cell in TiAl phase decreased by the addition of a small amount of carbon and nitrogen. The analysis of TiAl-1.0at%C alloys by an X-ray diffractometer showed the presence of Ti2AlC phase.