NUCLEATION AND GROWTH OF BETA'-SIALON

被引:65
作者
HWANG, SL [1 ]
CHEN, IW [1 ]
机构
[1] UNIV MICHIGAN,DEPT MAT SCI & ENGN,ANN ARBOR,MI 48109
关键词
D O I
10.1111/j.1151-2916.1994.tb07042.x
中图分类号
TQ174 [陶瓷工业]; TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
Elongated beta'-SiAlON grains grown from several fine-grained Ym/3Si12-(m+n)Alm+nOnN16-n compositions with alpha-Si3N4, AlN, Al2O3, and Y2O3 starting materials have been examined. These grains have large aspect ratios and are oriented along the [0001] axis. TEM structural and chemical analysis suggests that they are nucleated from various seed crystals, which can be alpha-Si3N4, beta-Si3N4, or other beta'-SiAlON. The beta'-SiAlON seed and the initial precipitation on beta-Si3N4 show a higher content of Al and O, indicating that a large transient supersaturation of Al and 0 in the liquid is instrumental for beta'-SiAlON formation, whereas subsequent growth proceeds under a much lower driving force. The misfit between phases is accommodated by interfacial dislocations (c-type and a-type). Fully grown beta'-SiAlON grains usually contain several variants independently nucleated from the same seed. In particular, the two alternative alpha/beta phase-matching possibilities result in two [0001] growth habits separated by a twin boundary.
引用
收藏
页码:1719 / 1728
页数:10
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