The Isothermal Oxidation Response of a Gamma-Titanium Aluminide Alloy

摘要

The room temperature mechanical response of the alloy, γ-MET (Ti-46.5%Al-4%(Cr,Nb,Ta,B) at.%) in the primary anneal condition was characterized. The alloy showed a yield strength of 463 MPa, an ultimate tensile strength of 499 MPa, a modulus of 144 GPa and 0.55% elongation. The Poisson ratio was found to be 0.24. Isothermal gravimetric analysis was conducted on rectangular coupons of the alloy in air at temperatures between 700 and 1000℃. The mass gain data show kinetics that is dominated by TiO_2 kinetics below approximately 750℃ and display reduced rate constants at 800℃ and higher. Scanning electron microscopy was conducted on plan view and cross sections that were prepared from the oxidized material to characterize the oxide composition and morphology. These results indicate the presence of a continuous alumina scale on the higher temperature samples.