The Isothermal Oxidation Behavior of a TiAl-Nb-V-Mo Alloy

ABSTRACT

The isothermal oxidation behavior of Ti-24Al-14Nb-3V-0.5Mo alloy in synthetic air from 700°C to 1000°C was studied. The main emphasis was focused on the effect of microstructure obtained by different processes of melting and hot rolling, i.e. large β and duplex of α₂+B2, on the oxidation resistance. Regardless of the microstructure, the overall oxidation process of the specimens exposed at 700°C was dominantly controlled by the beneficial effect of Nb-addition due to the formation of a continuous α-Al₂O₃ layer in the scale. However, both specimens showed poor oxidation resistance above 900°C, especially for the as-rolled specimen, because of higher volume fraction of the α2 phase. The spallation occurred in both specimens at 1000°C, which was probably relative to the formation of Ti₂AlN between the thick scale and the substrate except for the TiO₂ and α-Al₂O₃.

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