서지주요정보
알루미나에서 확산정합 변형과 순은에서 열적 변형에 의한 입계이동 = Grain boundary migration induced by diffusional coherency strain in $Al_2O_3$ and by thermal strain in Ag
서명 / 저자 알루미나에서 확산정합 변형과 순은에서 열적 변형에 의한 입계이동 = Grain boundary migration induced by diffusional coherency strain in $Al_2O_3$ and by thermal strain in Ag / 한상철.
저자명 한상철 ; Han, Sang-Cul
발행사항 [대전 : 한국과학기술원, 1995].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8005686

소장위치/청구기호

학술문화관(문화관) 보존서고

DMS 95005

휴대폰 전송

도서상태

이용가능

대출가능

반납예정일

초록정보

When alumina polycrystal is heat-treated at 1400 and 1500℃ with $Al_2O_3-Cr_2O_3$ powder mixtures, the grain boundaries migrate, forming behind them a solid solution enriched with $Cr_2O_3$. The migration rate increases with the heat-treatment temperature and the $Cr_2O_3$ content in the mixture. The driving force for the migration is believed to arise from the coherency strain in the $Cr_2O_3$ diffusion zone in front of the migrating grain boundaries. The migrating grain boundaries develop strong faceting with flat segments meeting at sharp edges. Because of the elastic anisotropy of alumina, the diffusional coherency strain energy $G_c(n)$ varies with the surface orientation n of the retreating grain, but the variation is smooth at the minimum in the polar plot of $G_c(n)$. Therefore, smoothly curved boundaries meeting at sharp edges are predicted for the growth shape contrary to the observed flat facet boundaries. It is suggested that the grain boundary mobility may also vary with the grain surface orientation and therefore influence the growth shape. When pure silver is heat-treated at 800℃ in $N_2$ or $O_2$ after heat-treating at 800℃ for 48 h in $N_2$ and water-quenching, the grain boundaries migrate. On slow-cooling and slow-heating in $N_2$, the grain boundaries don't migrate. Therefore, the driving force the migration is believed to arise from the residual stress of the surface which is generated by the water quenching. The boundary migration is observed in the specimen which is heat-treated at 520℃ for 1 h in $O_2$ after slow-cooling and slow-heating in $N_2$. Its driving force is believed to be the difference of the surface energy change between the neighboring grains when the atmosphere is change from $N_2$ to $O_2$. It can be explained that the quantity of the surface energy change on changing the atmosphere is sufficient to drive the boundary migration.

서지기타정보

서지기타정보
청구기호 {DMS 95005
형태사항 iv, 131 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Sang-Chul Han
지도교수의 한글표기 : 윤덕용
지도교수의 영문표기 : Duk-Yong Yun
학위논문 학위논문(박사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 수록
주제 Diffusion.
Silver.
Aluminum oxide.
Grain boundaries.
입계 이동. --과학기술용어시소러스
변형 에너지. --과학기술용어시소러스
표면 에너지. --과학기술용어시소러스
Surfaces.
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