Characterisation of phase relations and properties in air-oxidised Ti3SiC2.

Abstract

The oxidation of Ti3SiC2 in air from 25 to 1450 degrees C is characterised by differential thermal and gravimetric analysis (DTA/TGA), X-ray diffraction (XRD), grazing-incidence synchrotron radiation diffraction (GISRD), neutron diffraction (ND), transmission electron microscopy (TEM), secondary ions mass spectroscopy (SIMS) and Vickers indentation. The diffraction results show that rutile formed at a temperature of similar to 750 degrees C. A glassy phase - formed at > 1000 degrees C - devitrified upon cooling to room temperature to form tridymite but crystallised to cristobalite at temperatures >= 1300 degrees C. Composition depth-profiling of the surface layer oxides by XRD, GISRD and SIMS revealed a graded distribution of phases (TiO2, SiO2 and Ti3SiC2) both at the nanoscale (<= 1100 degrees C) and microscale level (1200 degrees C), which is particularly distinct at the interfaces. The oxide layers also exhibit a graded variation in microhardness. © 2007, Elsevier Ltd.