Abstract
The results of fractographic investigations of intermetallic Ti-48Al-2Cr-2Nb alloys prepared by powder metallurgy are presented in the paper. Elementary Ti, Al, Cr, and Nb powders were used as a starting material for the specimen preparation. Powders were dry mixed in an attritor. The homogeneous mixture was compacted by cold isostatic pressing. The material has undergone simple (S) and double (D) extrusion. After that hot isostatic pressing and heat treatment followed. Mechanical properties in relation to the microstructure of intermetallic TiAlCrNb alloys were evaluated. At room temperatures the material D had a higher strength (511 MPa) than the material S (382 MPa). At higher temperatures the strength properties decreased to 430 MPa (D) and 370 MPa (S). The plastic properties were relatively low, less than 5 %, for all cases. The SEM investigation revealed that transcrystalline cleavage of γ-phase and transcrystalline cleavage of lamellar colonies are the main fracture mechanisms at room temperatures. Transcrystalline cleavage of lamellar colonies and intercrystalline separation are dominant at higher temperatures.

Key words
intermetallic Ti-48Al-2Cr-2Nb alloys, powder metallurgy, failure, mechanical properties

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