Additive and Impurity Distributions at Grain Boundaries in Sintered Alumina

Abstract
Additive and impurity distributions at grain boundaries in sintered Al2O3 were determined using a scanning Auger microprobe, transmission electron microscopy, metallography, and electron probe analysis. The results indicated that Ca was present uniformly at the boundaries as a segregant, whereas the Mg or Ni levels observed resulted from nonequilibrium spinel particles. The Ca concentrations were consistent with equilibrium segregation theory and followed an equilibrium segregation isotherm.