Rj. Xie et al., Texture development in silicon nitride-silicon oxynitride in situ composites via superplastic deformation, J AM CERAM, 83(12), 2000, pp. 3147-3152
Silicon nitride-silicon oxynitride (Si3N4Si2N2O) in situ composites have be
en fabricated via either the annealing or the superplastic deformation of s
intered Si3N4 that has been doped with a silica-containing additive, In thi
s study, quantitative texture measurements, including pole figures and X-ra
y diffraction patterns, are used in conjunction with scanning electron micr
oscopy and transmission electron microscopy techniques to examine the degre
e of preferred orientation and texture-development mechanisms in these mate
rials. The results indicate that (i) only superplastic deformation can prod
uce strong textures in the beta -Si3N4 matrix, as well as Si2N2O grains tha
t are formed in situ; (ii) texture development in the beta -Si3N4 matrix ma
inly results from grain rotation via grain-boundary sliding; and (iii) for
Si2N2O, a very strong strain-dependent texture occurs in two stages, namely
, preferred nucleation and anisotropic grain growth.