Microstructure and texture formation during hot rolling of niobium-rich γ TiAl alloys with different carbon contents

Microstructure and texture of γ-TiAl based alloys with smaller amounts of Al and Nb during hot rolling were analyzed. Three alloys of different carbon contents were processed through a powder metallurgical route and were degassed and subsequently hot-isostatically pressed (HIP). The texture measurements were performed by X-ray diffraction (XRD) in reflection geometry with filtered Cu Ka radiation. The volume fractions of the a2 phase and the γ-phase of the samples were estimated by XRD measurements and by quantitative metallographic evaluation conducted on light-optical microscope (LOM) images and scanning electron microscope (SEM) images. It was found that the main component of the rolling texture of the γ-phase in high Nb bearing TiAl based alloy was strong a2- fiber, which can be attributed to mechanical twinning.