In Situ Tem Investigation of the Oxidation of Titanium Aluminide Alloys

Transmission electron microscopy (TEM) of thin foil specimens during in-situ oxidation permits the study of oxide nucleation and growth. The results of such experiments on Ti₃Al (alpha-2), TLAl/Nb (alpha-2 plus beta) and TiAl (gamma) alloys are presented. Direct images of the earliest observable oxide particles were obtained. The preferential sites of oxygen attack, e.g. on dislocations, grain boundaries and second phases were investigated. Diffraction ring patterns provide information on the nucleation and growth of the first oxide phases.