In-situ characterization of phase transformations and microstructure evolution in a γ-TiAl based alloy

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The Minerals, Metals & Materials Society (TMS)
Phase diagrams and microstructures of titanium aluminides are rather complex and, so far, little data were observed in-situ at elevated temperatures. We report on two-dimensional high energy X-ray diffraction and complementary laser scanning confocal microscopy to characterize the appearing phases and to follow the phase evolution in-situ and in real time. As an example, the microstructure evolution of a quenched γ-TiAl alloy, consisting of α2-Ti3Al grains at room temperature, has been followed in both reciprocal and direct space as a function of temperature up to 1400°C. At 700 – 800°C extremely fine γ-laths are formed in α2-grains occurring through an oriented rearrangement of atoms. Streaks linking reflections of both phases testify from coherent lattice and orientation gradients in the transforming crystallite. At temperatures around the eutectoid temperature recrystallization effects and the γ->α phase transition take place leading to grain refinement.
Titanium, Phase transformations, Synchrotron radiation, Laser spectroscopy, Microstructure, Real time systems
Liss, K. D., Bartels, A., Clemens, H., Stark, A., Buslaps, T., Phelan, D., & Yeoh, L. A. (2008). In-situ characterization of phase transformations and microstructure evolution in a γ-TiAl based alloy. Paper presented to the 137th TMS Annual Meeting & Exhibition (TMS 2008) - "Linking Science and Technology for Global Solutions", 9th - 13th March 2008. Ernest N. Morial Convention Center: New Orleans, Louisiana, United States of America. In Y.W. Kim, D. Morris, R. Yang & C. Leyens (Eds.), Structural Aluminides for Elevated Temperatures: Gamma Titanium and Other Metallic Aluminides, (pp. 137-144). Warrendale, Pennsylvania, United States of America: The Minerals, Metals & Materials Society (TMS).