Depth profiling of near-surface information in a functionally graded alumina/aluminium titanate composite using grazing-incidence synchrotron radiation diffraction

Abstract Grazing-incidence synchrotron radiation diffraction (GISRD) has been successfully used for near-surface depth profiling of phase composition in a functionally graded alumina (A)/aluminium titanate (AT) composite prepared by an infiltration process. Depth profiling of near-surface layers both within the nanometer and micrometer range could be done by using angles of incidence below and above the critical angle ( α c ) for total external reflection. The penetration depth increased to several hundred angstroms as α approached α c . However, above α c there was a rapid increase in penetration depth to several thousand angstroms or more. As the penetration depth increased, the intensity of aluminium titanate peaks relative to those of alumina became less intense, indicating a graded change in the phase abundance. The presence of graded residual strains in the composite due to the thermal expansion mismatch between the phases has been computed and verified from the display of line shifts. The unique but powerful capability of GISRD as a tool for depth-profiling the near-surface information of graded materials has been demonstrated in this work.