서지주요정보
변형량과 입계 구조가 구리의 입자성장에 미치는 영향 = Effects of deformation and grain boundary structure on grain growth in Cu
서명 / 저자 변형량과 입계 구조가 구리의 입자성장에 미치는 영향 = Effects of deformation and grain boundary structure on grain growth in Cu / 구재본.
저자명 구재본 ; Koo, Jae-Bon
발행사항 [대전 : 한국과학기술원, 2000].
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등록번호

8011476

소장위치/청구기호

학술문화관(문화관) 보존서고

DMS 00031

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초록정보

In part Ⅰ, the effects of deformation and grain boundary structure on grain growth in Cu of 99.9999% purity have been studied. Firstly, the grain growth occurring after the large deformed specimens are recrystallized has been investigated. Stagnant grain growth occurs when the specimens are compressed to 20% and annealed at 600℃, 10% at 700℃, and 5% at 800℃. However, when the specimens are compressed to more than these deformations and annealed at each temperature, abnormal grain growth (AGG) occurs. The results indicate that there is a critical grain size for AGG at each temperature and as annealing temperature increases the critical grain size for AGG increases. When annealed at various temperatures after the same deformation (35%, 50%, 65%), the number of the abnormally large grains increases with increase of annealing temperature, and finally their impinged grain size decreases. When annealed at the same temperature (600℃, 800℃, 950℃) after various deformations, the number of the abnormally large grains increases with increase of deformation amount, and their size decreases. When annealed at 800℃ after 65℃ or 75℃ compression or at 950℃ after 50% compression, double AGG occurs. Double AGG occurs in the condition that the impinged grain size after AGG is smaller than the critical grain size at each emperature and therefore readily occurs during annealing at high temperature after high deformation. Secondly, the grain growth occurring in the specimens slightly deformed has been investigated. It is observed that when the specimens in stagnant grain growth conditions are slightly deformed, AGG readily occurs. If AGG is already occurring, the small deformation causes more grain to grow abnormally and sooner. The observations with transmission electron microscopy (TEM) show that the dislocation density within the grains after some growth in the deformed specimen is about same as that in the undeformed specimen. But the dislocation density at the grain boundaries of the deformed specimens remains high during the heat-treatment. Therefore, the main effect to small deformation is to increase the dislocatiion density at grain boundaries, which increases in effect their mobility at relatively small driving forces. The results obtained from experimental observations have been discussed in views of two-dimensional nucleation theory for AGG of polycrystalline materials. The observations with TEM show that the grain boundaries in the specimens where AGG or stagnant grain growth occurs are faceted, indicating atomically singular structure and the fraction of the faceted grain boundary decreases with increase of annealing temperature. The results support the hypothesis that AGG occurs because the faceted singular grain boundary migrates either by two-dimensional nucleation of the boundary steps or by spiral growth on defects. In part Ⅱ, the observations of island grains formed during annealing of pure Cu, their orientation determined by electron back scattered pattern, and their shrinkage upon further annealing are described and these results are discussed in terms of the dependence of the grain boundary migration on its structure. The island grains observer in the specimen where AGG occurs after prolonged annealing under stagnant grain growth condition have low angle misorientation relationship with abnormally large grains, indicating low grain boundry energy and mobility. In spite of their low energy and mobility, the island grains are unstable and eventually shrink. However, when AGG occurs very rapidly with fine matrix grains, even those grains with relatively high boundary energy and mobility are also trapped in the growing grains and shrink to disappear very rapidly.

서지기타정보

서지기타정보
청구기호 {DMS 00031
형태사항 v, 220 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Jae-Bon Koo
지도교수의 한글표기 : 윤덕용
지도교수의 영문표기 : Duk-Yong Yoon
수록잡지명 : "Island grains of low misorientation angles formed during abnormal grain growth in cu". Metall. mater. trans. A
학위논문 학위논문(박사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 : p. 219-220
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