Influence of a rich sulphur atmosphere on the phase development and kinetic behaviour of differentially processed RNT650?- TiAl alloys

The influence of sulphur atmosphere on conventionally cast (CM) and on electron beam melted (EBM) g -TiAl RNT650 alloy exposed to a 1% (vol.) H2S -air atmosphere at 650 degrees C for 500 h was investigated. The material produced by CM showed a lower mass gain than the EBM material. XRD and TEM/EDS analyses indicated the formation of rutile-TiO2/(a-Al2-O3 + rutile-TiO2)/amorphous-Al2O3 sequence of phases. In EBM a coarse crystalline layer rich in aluminium, oxygen and a small amount of sulphur was found. The higher content of sulphur was in the scale bottom intermixed with amorphous alumina.(c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).