Abstract
The present study aims at understanding the effect of simultaneous heating (780 °C) during laser direct energy deposition (LDED) on kinetics and mechanism of cyclic oxidation (from 700 to 900 °C in air) of niobium added tailored titanium aluminide (Ti45Al5Nb0.5Si) developed by LDED using a Nd:YAG laser using 500 W applied power, 300 mm/min scan speed and 2.2 g/min powder feed rate. The microstructure of LDED Ti45Al5Nb0.5Si consists of γ (TiAl) + α2 (Ti3Al) lamellae, however, the mass fraction of γ (TiAl) is found to be higher in case of simultaneous heating as compared to the same without heating. Simultaneous heating increased the activation energy of cyclic oxidation from 231 kJ/mol (for the sample without heating) to 249 kJ/mol. The mechanism of cyclic oxidation is explained.
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