Effect of Nb-ion implantation on the oxidation resistance of TiAl

The TiAI specimens implanted with Mb ions of a dose of 1.2 x 10(21) m(-2) were subjected to isothermal and cyclic oxidation tests at 1200 K in a flow of purified oxygen under atmospheric pressure. The results were compared with those for Nb-free specimens. The implantation of Nb ions decreases the overall oxidation rate in the both tests. There is no scale spallation from the Nb-implanted specimen during the cyclic oxidation. Two kinds of scales were formed on each specimen: an alumina-rich (virtually alumina) scale and a two-layer scale which has been often observed. The implantation of Nb improves the mechanical integrity of the alumina scale and decreases the growth rate of the two-layer scale.