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Sequential Precipitation of MgAl 2 O 4 on Mg 1‐x Ca x Al 2 O 4 in Hot‐Pressed MgO Single Crystals
Author(s) -
FUJIMOTO MASAYUKI,
CHIANG YETMING,
KINGERY W. DAVID
Publication year - 1988
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1988.tb05847.x
Subject(s) - spinel , precipitation , dislocation , transmission electron microscopy , impurity , scanning electron microscope , materials science , crystallography , hot pressing , mineralogy , solid solution , analytical chemistry (journal) , metallurgy , chemistry , composite material , nanotechnology , physics , organic chemistry , chromatography , meteorology
In a hot‐pressed and deformed MgO single crystal, precipitates of Mg 1‐x Ca x Al 2 O 4 spinel upon which MgAl 2 O 4 spinel subsequently precipitated were observed and analyzed using transmission electron microscopy and scanning electron microscopy. This behavior is related to the respective solubility limits of CaO and Al 2 O 3 in MgO at the hot‐pressing temperature and may be aided by impurity segregation to the dislocations. The spinel selectively precipitated at the nodes of a dislocation network which was formed during [001] hot‐pressing deformation, as a result of the reaction b 3 = b 1 + b 2 = (1/2) [011] + (1/2) = [001]. The dislocation is sessile, and the precipitates have a <100> matrix ? <100> spinel coherent relationship.