Microstructure and mechanical properties of high niobium containing TiAl alloys elaborated by spark plasma sintering
Résumé
Spark Plasma Sintering (SPS) is used to process TNB alloys. Pre-alloyed powders (Tie-46Al-9Nb) were sintered between 975 °C and 1300 °C under 100 MPa. The microstructures of the products are determined by X-ray diffraction and by scanning and transmission electron microscopy. Their mechanical properties are evaluated by tensile tests performed at room temperature and creep experiments at 700 °C under 300 MPa stress.
Depending on the sintering temperature, two-phased, duplex and lamellar microstructures have been obtained. A quasi-$\alpha$2 phase has been observed, which is in fact an $\alpha$2 phase in which Nb atoms have substituted Ti atoms. The TNB alloys consolidated by SPS are stronger than the alloys previously elaborated by SPS using Tie-47Al-2Cr-2Nb and Tie-44Al-2Cr-2Nb-1B powders but they exhibit a lower ductility. Moreover, some specimens broke prematurely due to Fe inclusions.
Domaines
MatériauxOrigine | Fichiers produits par l'(les) auteur(s) |
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