Place: 43. Metallographie-Tagung 2009, Eurogress Aachen, Germany
Martin Wagner, Department of Werkstoffwissenschaft (WW), TU Chemnitz, Chemnitz, Germany
The properties of two-phase γ-TiAl alloys strongly depend on their microstructural constitution. An accurate quantitative microstructural characterization is therefore quite important. The present work introduces special preparation procedures utilizing the focused ion beam (FIB) technique to generate high contrast ion-induced secondary electron images. Two-phase structures, e.g. fine-lamellar colonies in γ-TiAl, can be imaged in high resolution with respect to individual phases, which allow to quantify the α2/γ phase fractions by conventional image analysis. To validate these data, we compare the FIB results to those obtained by phase determination using the electron backscatter diffraction (EBSD) method. The FIB technique generally provides higher α2-fractions, due to an improved lateral resolution near grain boundaries and interfaces compared to EBSD. Our results indicate that the FIB technique is a simple, fast and more exact way to characterize microstructural features with respect to different phase constitutions in TiAl.