Microstructure and mechanical properties of a spark plasma sintered Ti-45Al-8.5Nb-0.2W-0.2B-0.1Y alloy

A high Nb containing TiAl alloy from pre-alloyed powder of Ti-45Al-8.5Nb-0.2B-0.2W-0.1Y was processed by spark plasma sintering (SPS). The effects of sintering temperature on the microstructure and mechanical properties were studied. The optimized conditions yield high densities and uniform microstructure. Specimens sintered at 1100 degrees C are characterized by fine duplex microstructure, leading to superior room temperature mechanical properties with a tensile strength of 1024 MPa and an elongation of 1.16%. Specimens sintered at 1200 degrees C are of fully lamellar microstructure with a tensile strength of 964 MPa and an elongation of 0.88%. The main fracture mode in the duplex microstructure was transgranular in the equiaxed gamma grains and interlamellar in the lamellar colonies. For the fully lamellar structure, the fracture mode was dominated by interlamellar, translamellar and stepwise failure. (C) 2009 Elsevier Ltd. All rights reserved.