Dendritic structural transformation of laser surface remelted γ-TiAl based alloy during post-heat treatment

Laser surface remelting followed by heat treatments at 1000 degrees C for different time was carried out on gamma-TiAl based alloy. The characteristics of structural transformation of laser surface remelted gamma-TiAl based alloy were investigated by high-temperature microscope, TEM and XRD. The results show that the phase transformation (alpha(2) -> gamma) in TiAl alloy occurred at the earlier stage of post-heat treatment, and the dendritic structure transformed firstly at the intergranular, then expanded into the transgranular, finally changed to ultrafine equiaxed grain structure, at the same time, micro-hardness of laser-surface remelted gamma-TiAl based alloy had the corresponding change with the structural trans fori-nation. (c) 2005 Elsevier B.V. All rights reserved.