EFFECT OF OXYGEN PARTIAL PRESSURE ON THE PHASE STABILITY OF Ti3SiC2

摘要

The thermal stability and topotactic transition of Ti3SiC2 in vacuum,argon and air have been investigated by synchrotron radiation diffraction (SRD),in-situ neutron diffraction (ND) and secondary ion mass spectroscopy (SIMS).In the presence of a low oxygen partial pressure such as in vacuum or argon,Ti3SiC2 undergoes a surface dissociation to form non-stoichiometric TiC and/or TisSi3C at 1200 °C.In contrast,it forms non-stoichiometric surface oxides of rutile at 1000 °C and cristobalite at 1300 °C when exposed to an oxygen-rich environment.Near-surface depth profiling of vacuum-treated Ti3SiC2 by SIMS has revealed a distinct gradation in phase composition and confirmed the existence of TisSi3C in solid solution with oxygen.