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Title: Nano-precipitation in hot-pressed silicon carbide

Abstract

Heat treatments at 1300 degrees C, 1400 degrees C, 1500 degrees C, and 1600 degrees C in Ar were found to produce nanoscale precipitates in hot-pressed silicon carbide containing aluminum, boron, and carbon sintering additives (ABC-SiC). The precipitates were studied by transmission electron microscopy (TEM) and nano-probe energy-dispersive X-ray spectroscopy (nEDS). The precipitates were plate-like in shape, with a thickness, length and separation of only a few nanometers, and their size coarsened with increasing annealing temperature, accompanied by reduced number density. The distribution of the precipitates was uniform inside the SiC grains, but depleted zones were observed in the vicinity of the SiC grain boundaries. A coherent orientation relationship between the precipitates and the SiC matrix was found. Combined high-resolution electron microscopy, computer simulation, and nEDS identified an Al4C3-based structure and composition for the nano-precipitates. Most Al ions in SiC lattice exsolved as precipitates during the annealing at 1400 to 1500 degrees C. Formation mechanism and possible influences of the nanoscale precipitates on mechanical properties are discussed.

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Director, Office of Science. Office of Basic Energy Studies. Division of Materials Sciences (US)
OSTI Identifier:
789123
Report Number(s):
LBNL-46447
Journal ID: ISSN 0022-2461; JMTSAS; R&D Project: 512301; TRN: AH200137%%329
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Journal of Materials Science
Additional Journal Information:
Journal Volume: 36; Journal Issue: 22; Other Information: Journal Publication Date: Nov. 2001; PBD: 16 May 2000; Journal ID: ISSN 0022-2461
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ADDITIONS; GRAIN BOUNDARIES; HEAT TREATMENTS; MECHANICAL PROPERTIES; SILICON CARBIDES; BORON ADDITIONS; CARBON ADDITIONS; PRECIPITATION HARDENING; HOT PRESSING; SIC NANOSCALE PRECIPITATE MICROSTRUCTURE HEAT TREATMENT

Citation Formats

Zhang, Xiao Feng, Sixta, Mark E., Chen, Da, and De Jonghe, Lutgard C. Nano-precipitation in hot-pressed silicon carbide. United States: N. p., 2000. Web.
Zhang, Xiao Feng, Sixta, Mark E., Chen, Da, & De Jonghe, Lutgard C. Nano-precipitation in hot-pressed silicon carbide. United States.
Zhang, Xiao Feng, Sixta, Mark E., Chen, Da, and De Jonghe, Lutgard C. Tue . "Nano-precipitation in hot-pressed silicon carbide". United States. https://www.osti.gov/servlets/purl/789123.
@article{osti_789123,
title = {Nano-precipitation in hot-pressed silicon carbide},
author = {Zhang, Xiao Feng and Sixta, Mark E. and Chen, Da and De Jonghe, Lutgard C.},
abstractNote = {Heat treatments at 1300 degrees C, 1400 degrees C, 1500 degrees C, and 1600 degrees C in Ar were found to produce nanoscale precipitates in hot-pressed silicon carbide containing aluminum, boron, and carbon sintering additives (ABC-SiC). The precipitates were studied by transmission electron microscopy (TEM) and nano-probe energy-dispersive X-ray spectroscopy (nEDS). The precipitates were plate-like in shape, with a thickness, length and separation of only a few nanometers, and their size coarsened with increasing annealing temperature, accompanied by reduced number density. The distribution of the precipitates was uniform inside the SiC grains, but depleted zones were observed in the vicinity of the SiC grain boundaries. A coherent orientation relationship between the precipitates and the SiC matrix was found. Combined high-resolution electron microscopy, computer simulation, and nEDS identified an Al4C3-based structure and composition for the nano-precipitates. Most Al ions in SiC lattice exsolved as precipitates during the annealing at 1400 to 1500 degrees C. Formation mechanism and possible influences of the nanoscale precipitates on mechanical properties are discussed.},
doi = {},
journal = {Journal of Materials Science},
issn = {0022-2461},
number = 22,
volume = 36,
place = {United States},
year = {2000},
month = {5}
}