Effects of yttrium doping alpha-alumina: I, microstructure and microchemistryстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The influence of yttrium doping on the microstructure and microchemistry of hot-pressed ct-alumina was investigated using a combination of electron microscopy techniques. The implications of microstructure and microchemistry on the improved creep behavior of the doped material are discussed. The samples doped only with yttrium had a bimodal grain-size distribution that was strongly correlated to the frequency and distribution of Y3Al5O12 (YAG) precipitates in the microstructure. Yttrium segregated to most of the grain boundaries, with a normal excess concentration of Gamma = 3.3 +/- 0.9 atoms/nm(2) at random boundaries. Two types of twin boundaries (Sigma 3 and Sigma 7) accommodated no yttrium, None of the boundaries or triple-point junctions contained a glassy grain-boundary phase. Strong interaction of the grain boundaries and dislocations with YAG precipitates indicated a pinning mechanism by the precipitates. Yttrium doping did not appear to favor formation of special boundaries in alpha-alumina.