from the conferences organized by TANGER Ltd. provisional website
Samples of in-situ TiAl-based matrix composite reinforced with Ti2AlC particles were prepared by vacuum induction melting of a charge with a nominal composition Ti-47Al-5Nb-1C-0.2B (at%) in graphite crucibles and centrifugal casting into a graphite mould. The as-cast samples were subjected to hot isostatic pressing (HIP) and multi-step heat treatments. High temperature compression tests at 1000 °C were carried out on the heat-treated in-situ composite with an optimised microstructure. During compressive deformation, the work hardening is the predominant mechanism at small strains due to an increment of dislocation density in the in-situ composite. At higher strains, dynamic recovery and recrystallization act as main softening mechanisms and exceed the work hardening, which leads to a decrease of the compressive flow stress with increasing strain. The creep deformation curves exhibit a primary creep stage, which is followed by a tertiary creep stage at temperatures ranging from 800 to 900 °C and applied stresses ranging from 150 to 250 MPa. The high temperature creep resistance of the studied in-situ composite is superior compared with that of some TiAl-based alloys with fully lamellar, nearly lamellar, convoluted and pseudo-duplex microstructures at a temperature of 800 °C and applied stress of 200 MPa.Keywords: TiAl, composites, mechanical behaviour, creep, microstructure
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