The present study was undertaken to test the validity of existing mode
ls for: (i) the residual internal stresses which arise due to thermal
and elastic mismatch in duplex systems; and (ii) the critical particle
diameter for spontaneous cracking. The specimens studied were bulk nu
cleated, partially crystallized 17.20Na(2)O-32.09CaO-48.12SiO(2)-2.59P
(2)O(5) (mol%) glasses. The residual stress was determined by an X-ray
diffraction technique for a particular set of hkl planes. The crystal
diameters and volume fractions crystallized were measured by an image
analyzer system. The experimental residual stress was in agreement wi
th the calculated value within the measurement errors. On the other ha
nd, the theoretical value of the critical particle diameter, calculate
d by an energy balance approach, was more than ten times smaller than
the experimental value, suggesting that the semi-spherical crack assum
ed in the model does not hold for our system. A preliminary fitting wi
th a fracture mechanics model was also carried out.