Rs. Hay, THE USE OF SOLID-STATE REACTIONS WITH VOLUME LOSS TO ENGINEER STRESS AND POROSITY INTO THE FIBER-MATRIX INTERFACE OF A CERAMIC COMPOSITE, Acta metallurgica et materialia, 43(9), 1995, pp. 3333-3347
Citations number
83
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
The effect of the 11 vol% loss during reaction of yttrium-aluminum gar
net (YAG) and zirconia was observed in zirconia coated single-crystal
alumina fiber-YAG matrix composites. The reaction caused plastic defor
mation in the alumina fibers, and possibly a minor amount of porosity
at fiber-matrix interfaces that was usually indistinguishable from mat
rix porosity. The results were analyzed by models for diffusive cavita
tion modified to use reaction self-stress. Crack-healing, tensile stre
ss states along the reaction front that approach plane stress, and the
small volume of self-stressed material make crack-like pores unlikely
at the high temperatures required for reaction. Smaller matrix grains
might promote formation of smaller cavities but are also incompatible
with high temperature. Both modeling and experiment suggest that suff
icient porosity for crack deflection and fiber pullout cannot form unl
ess processing methods that form dense composites at lower temperature
s are used.