In-situ study of phases and microstructures of titanium aluminides

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Australian Institute of Physics
The phase diagrams and microstructures of titanium aluminides are rather complex and little or no data were observed during in-situ experiments at elevated temperatures up to 1400 °C, where different processes compete, such as recovery, phase transitions, recrystallization, twinning, crystallite growth, segregation and more. Two-dimensional high energy X-ray diffraction is a powerful method to characterize the phase composition and modern synchrotron sources are strong enough to follow the evolution of the material in real time. Besides texture relations as well as grain and phase correlations, we followed the coherent transition from the alpha to the gamma phase and vice versa. A streak of diffuse scattering appears in reciprocal space bridging reciprocal lattice points of both phases and disappears after the transition completed. This proves, that the phase transition is a well ordered process. Furthermore, the system has been observed in a Laser Scanning Confocal Microscope in situ and in real time, relating the micro structure to the diffraction pattern. Fine laths of the lamellar alpha/gamma grains are created during the phase transition and coarsen as a function of time. The unique combination of the two complementary in-situ techniques was used for the first time and reveals novel, consistent information on a phase transformation in a real solid.
Phase diagrams, Microstructure, Titanium, Temperature range 1000-4000 K, Recrystallization, Twinning, X-ray diffraction, Crystal lattices
Liss, K. D., Yeoh, L., Bartels, A., Clemens, H., Phelan, D., & Buslaps, T. (2006). In-situ study of phases and microstructures of titanium aluminides. Paper presented at the Australian Institute of Physics 17th National Congress 2006, Brisbane Convention and Exhibition Centre, Brisbane Australia, Sunday 3 - Friday 8 December 2006. Retrieved from: