Role of microstructure in fracture performance of TiAl intermetallics at room and elevated temperatures is analysed in the paper. Tensile properties, flexural strength and fracture toughness are evaluated for Ti40Al2Cr2Nb1B and Ti46Al0,7Cr0,1Si7Nb0,2Ni alloys. Positive Nb effect on fracture resistance is revealed. Fracture toughness of the high-Nb alloy is increased at contemporary increase of tensile and flexural strength. Fracture surfaces are evaluated using scanning electron microscopy, showing the key role of mechanical twinning in deformation of both alloys. As a governing mechanism of the crack initiation, a microcrack nucleation at boundaries between deformation twins and <$E gamma>-TiAl grains is confirmed. Extensive development of shear ligament toughening is observed supplying quite good fracture toughness values in high-Nb alloy. Based on findings, obtained key aspects of the effect of separate microstructural components are discussed.

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