GRAIN BOUNDARY PHENOMENA IN PARTIALLY STABILIZED ZIRCONIA POLYCRYSTALS ZJAWISKA ZACHODZACE NA GRANICACH ZIAREN W CAESCIOWO STABILIZOW ANYM DWUTLENKU CYRKONU

摘要

The microstructure and chemistry of the grainboundary (GB) migration process was investigated in ZrO2 withthe addition of 12 mol.% (17 wt.%) CeO2 and 1 mol.% (0.8wt.%) La2O3, as well as in ZrO2 doped with 3 mol.% (5 wt.%)Y2O3 ceramics by means of the scanning and transmissionelectron microscopy combined with an energy dispersive X-raymicroanalysis. The investigation showed that during annealing at1775 K, the GB migration is accompanied by the change of thesolute content within the zone left behind the boundary. ForZrO2+CeO2 the zone is Ce and La enriched showing similarity toalloying case of diffusion induced grain boundary migration. Thesuccessive backward movement of the GB results in the decreasein Ce and La content. In ZrO2+Y2O3 after 1 hour annealing, thearea swept by the moving boundary is strongly enriched inyttrium while yttrium content (100 hours) results in theformation of the transition zone with variable yttrium contentwhich resembles so-called precipitate free zone. In some grainsthe formation of the plate-like structure with approximately thesame cerium and yttrium contents as those in the matrix, wasidentified as martensitic transition of the tetragonal phase to monoclinic one.