Investigation of the microstructure of Al-Ti alloy

ABSTRACT MSc Thesis INVESTIGATION OF THE MICROSTRUCTURE OF Al-Ti ALLOY Koksal YILDIZ Fırat University Graduate School of Natural and Applied Sciences Department of Physics 2005, Page : 129 In this thesis, the microstructures of Al-Ti (1, 2 wt.%) alloys have been investigated by electron microscopy. These alloys were melted in a vacuum furnace at 800 °C. Al-Ti (1 %) alloys were grown by Modified Bridgman Technique at speeds of 165, 16 and 8 um/s and Al-Ti (2 %) in a casting furnace. Scanning electron microscope (SEM) observations and energy- dispersive x-ray analyses (EDX) showed that the phase structure of Al-Ti (1 %) alloy at 165 um/s is composed of Al matrix and C, Ni, Fe and Si particles and Al-Ti (1 %) alloys at 16 and 8 um/s have only the Al matrix and C particles. It was also found that the Al-Ti (2 %) form the Al matrix and intermetallic TiAl with different sizes and morphologies. The microstructures of Al- Ti (1, 2 %) alloys have been examined, using bright-field and dark-field transmission electron microscope (TEM) images and selected area diffraction (SAD) patterns. It has been observed that the Al-Ti (1 %) at 8 um/s had regular big grains and Al-Ti (2 %) small grains with different sizes and orientations. The Al-Ti (2 %) sample has also been investigated by high resolution electron microscope (HREM). The lattice space of the sample has been calculated as dhkp 0.141 nm. It has been seen that the solidification conditions and contents of Ti are very effective on the phase components and microstructures. Keywords : Al-Ti Alloy, Microstructure, TiAl, Electron microscopy. XVI