A study of grain boundary segregation and determination of thickness of segregate layer of a sialon ceramic using auger spectroscopy

Abstract

This paper presents a method of analysing grain boundary chemical composition and determination of grain boundary thickness of ceramic materials by Auger Electron Spectroscopy (AES). A sialon ceramic hot pressed with Mn3O4 was used as the ceramic sample. The AES analysis of intergranular grain boundary fracture surfaces of the ceramic indicated the presence of Mn, Al, Si, O and impurity Ca at grain boundaries. The chemical profile of segregate atoms normal to the fracture surface was determined using the sputtering technique and AES analysis alternatively. The approximate thickness of the boundary layer phase was estimated from these chemical profiles and it was found to be about 15 - 20 A. This value is somewhat lager than the value (10 A) reported by high resolution electron microscopy. This is because of the presence of lager volumes of residual intergranular glassy phase at triple junctions of the ceramic and also the uncertainty in defining the boundary limits in the AES profiles. However AES may be the most suitable technique available for analyising a thin layer of boundary interface.