Selected Methods of Quantitative Phase Analysis of an Additively Manufactured TNM Titanium Aluminide Alloy

The properties of intermetallic titanium aluminides, such as the so-called TNM alloy, which is, owing to its high specific strength and low density, already used in the aviation and automotive sector in the temperature range from 600-800 degrees C, are highly dependent on the fractions and nature of the present phases. Reliable options of quantitative phase analysis are therefore indispensable. Against this background, samples of an additively manufactured TNM alloy with the composition Ti-42, 1Al-4, 1Nb-1.0Mo-0.1B (at. %) were metallographically analyzed and the phase fractions of the alpha(2)- , beta(0)- and gamma-phases were quantitatively determined by image analysis, electron backscatter diffraction, and Rietveld analysis in the course of X-ray diffraction experiments performed in this work. With regard to the fractions of the alpha(2) and gamma phases, different results were obtained for the three methods applied which can be attributed to the characteristics of additive manufacturing and the quantitative phase analysis of multiphase samples.