This study concentrates on the microstructure refinement, high and low temperature mechanical properties and oxidation resistance of a Ti-46Al-8Ta-xN (x=0-2 at. %). The achieved results showed that alloying with N causes dendrite refinement, reduction of the retained metastable B2 phase and changing the ? primary phase to the ? phase during solidification in the as-cast microstructure. Moreover, the effect of N on interlamellar spacing, amount of constituent phases, and also T? and TE was not uniform. The hot oxidation resistance is increased with an increase in N content up to 0.45 at. % whereas a further increase in N content decreases the hot oxidation resistance. The results showed that the maximum small punch load at room temperature and 850 ?C enhanced at the expense of displacement at the onset of fracture and with increasing N content up to 0.45-1.05 at. %, beyond which the maximum load was dropped despite increasing in hardness and also more Ti2AlN precipitation and grain refinement. While crack-tip plastic deformation, crack-bridging ligaments and plasticity around crack tips occurred in the fracture surface of the low-N alloys, a high amount of accumulated nitrides act as crack initiation sites and deteriorates mechanical properties of the high-N alloy. Keywords
