Article ID Journal Published Year Pages File Type
5454764 Materials Characterization 2017 7 Pages PDF
Abstract
The microstructure and solidification behavior of high Nb containing TiAl alloys with the composition of Ti-46Al-8Nb-xC (x = 0.1, 0.7, 1.4, 2.5 at.%) prepared by arc-melting method have been investigated in this work. The results give evidence that the addition of carbon changes the solidification behavior from solidification via the β phase to the peritectic solidification. And carbon in solid solution enriches in the α2 phase and increases the microhardness. As the carbon content increases to 1.4 at.%, plate-shape morphology carbides Ti2AlC (H phase) precipitate from the TiAl matrix which leads to the refinement microstructure. By aging at 1173 K for 24 h after quenching treatment, fine needle-like and granular shape Ti3AlC (P phase) carbides are observed in the matrix of Ti-46Al-8Nb-2.5C alloy, which distribute along the lamellar structure or around the plate-shape Ti2AlC. Transmission electron microscope observation shows that the Ti3AlC carbides precipitate at dislocations. The phase transformation in-situ observations indicate that the Ti2AlC carbides partly precipitate during the solid state phase transformation process.
Related Topics
Physical Sciences and Engineering Materials Science Materials Science (General)
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