The isothermal and cyclic high temperature oxidation behaviour of Ti-48Al-2Mn-2Nb compared with Ti-48Al-2Cr-2Nb and Ti-48Al-2Cr
The isothermal and cyclic oxidation behaviour of Ti-48A1-2Mn-2Nb (at.%) were studied at high temperatures in air in comparison with the intermetallic alloys Ti-48Al-2Cr-2Nb and Ti-48Al-2Cr. Tests were performed in air between 800 C and 900 C. At 800 C Ti-48Al-2Mn-2Nb showed an excellent oxidation resistance under isothermal and cyclic conditions, comparable with Ti-48A1-2Cr-2Nb, and superior to Ti-48Al-2Cr. At 900 C the isothermal oxidation behaviour of Ti-48Al-2Mn-2Nb was similar to that of Ti-48Al-2Cr-2Nb, but much lower than that of Ti-48Al-2Cr. Upon cooling the oxide scale formed on Ti-48Al-2Mn-2Nb was prone to spallation. During the cyclic oxidation at 900 C, a steady state condition is reached for both niobium bearing materials, with a net linear mass loss rate, due to spallation and (re-) growth of the oxide scale. During the initial stage of oxidation of all tested materials a complex multi-phased and multi-layered scale was formed consisting of alpha-Al(2)O(3), TiO(2) (rutile), TiN and Ti(2)AlN. After longer exposure times the outer scale was dominated by TiO(2). In case of the niobium containing materials no loss of protectivity of the oxide scale was found during the growth of the outer TiO(2) layer (under isothermal conditions). Two-stage oxidation experiments with isotope tracers were performed to study the oxidation mechanism in more detail.
Bibliographic Reference: Article: Intermetallics (1998)
Record Number: 199811168 / Last updated on: 1998-10-09
Original language: en
Available languages: en