Published online by Cambridge University Press: 10 February 2011
Microstructure of TiAl produced by Laser Engineered Net Shaping (LENS) has been characterized using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has been shown that the substrate has a significant effect on the microstructure deposited. Depending on operational parameters, either equiaxed γ-TiAl/α2 -Ti3AI or single phase α 2 microstructure can be obtained. In-situ heating experiments reveal that nucleation of lamellae often starts at grain boundaries in this retained α 2grains. By careful control of post heat treatment, an ultra fine lamellar microstructure may be obtained, which may significantly improve tensile property in these alloys [3].