Effect of SPS Temperature on Microstructure and Mechanical Properties of TiAl Alloys

Abstract:

The spark plasma sintering (SPS) technique was used to consolidate pre-alloyed powder of Ti-45Al-2Cr-2Nb-0.2W produced by plasma rotating electrode processing (PREP). The powder was sintered at temperatures between 1150 and 1250 oC，and the effects of sintering temperature on the microstructure and the mechanical properties were studied. The optimized conditions yield high densities and uniform microstructure. Specimens sintered at 1150 oC are characterized by fine duplex microstructure, leading to superior room temperature mechanical properties with a tensile strength of 1026 MPa and an elongation of 1.12%, while the specimen sintered at 1250 oC are of fully lamellar microstructure with a tensile strength of 953 MPa and an elongation of 0.92%. The main fracture mode in the duplex microstructure is transgranular in the equiaxed γ grains and interlamellar in the lamellar colonies, and for the fully lamellar microstructure the dominant fracture mode is interlamellar, translamellar and stepwise failure.