Two influence factors on oxidation of TiAl

Effects of surface roughness and atmosphere flow ability on 900 'C interrupted oxidation behavior of five kinds of TiAl-based alloys (Ti-50A1, Ti-48A1, Ti-52A1, Ti-48Al-lCr, and Ti-48A1-4Cr) in as-cast state were investigated by TGA method. The results show that oxidation extent of all TiAl-based alloys becomes heavier as surface roughness increases from Ral. 6 to Ral 2.5. Comparing with static air (v = 0 mm • s^-1), air flowing (v = 1 mm • s^-1) also causes the degradation of oxidation resistance of TiAl-based alloys. The former result is due to the oxidation-caused internal stresses and inevitable calculation error, the later one is induced by the difference of supplementation of oxygen in atmosphere, but both of them are related to fragmentation oxidation period.