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Sn-4.0wt%Ag-0.5wt%Cu 솔더 접합계면의 강도특성과 미세파괴거동에 대한 In-situ관찰
이경근,최은근,추용호,김진수,이병수,안행근,Lee, Kyung-Keun,Choi, Eun-Geun,Chu, Yong-Ho,Kim, Jin-Soo,Lee, Byung-Soo,Ahn, Haeng-Keun 한국재료학회 2008 한국재료학회지 Vol.18 No.1
The micro-structural changes, strength characteristics, and micro-fractural behaviors at the joint interface between a Sn-4.0wt%Ag-0.5wt%Cu solder ball and UBM treated by isothermal aging are reported. From the reflow process for the joint interface, a small amount of intermetallic compound was formed. With an increase in the isothermal aging time, the type and amount of the intermetallic compound changed. The interface without an isothermal treatment showed a ductile fracture. However, with an increase in the aging time, a brittle fracture occurred on the interface due mainly to the increase in the size of the intermetallic compounds and voids. As a result, a drastic degradation in the shear strength was observed. From a microshear test by a scanning electron microscope, the generation of micro-cracks was initiated from the voids at the joint interface. They propagated along the same interface, resulting in coalescence with neighboring cracks into larger cracks. With an increase in the aging time, the generation of the micro-structural cracks was enhanced and the degree of propagation also accelerated.
합금화용융아연도금강판의 미세파괴거동에 대한 In-situ 관찰
문현수,부현덕,추용호,안병국,김영근,안행근,Mun Hyun-Su,Bu Hyun-Duck,Chu Yong-Ho,Ahn Byung-Kuk,Kim Young-Geun,Ahn Haeng-Keun 한국재료학회 2004 한국재료학회지 Vol.14 No.9
In-situ observation in SBM on the microfracture behavior of coating layer was performed for GA steel sheets that have various Fe contents and thickness of coating layer. In case of cross sectional side of coating layer that was in a tensile stress state during bending, fine perpendicular crack pre-induced during galvannealing grew and propagated rapidly toward the coating surface with the increase of strain. And then it grew and propagated along the ${\Gamma}/Fe$ matrix interface, and combined with the nearest another perpendicular crack. Consequently, flaking occurred. The more Fe content and thickness of coating layer increased, the more average crack interval and flaking resistivity increased. Exfoliation was little observed at coating surface in a tensile stress state.
精密測定 計器用 Stainless Steel의 諸性質에 미치는 熱處理의 影響
金善泰,安幸根,韓泰鍾 Natural Science Research Institute JEONJU UNIVERSI 1987 전주대학교 자연과학연구소 학술논문집 Vol.2 No.2
The changes of microstructure and hardness with the various heat treatments on the properties of Fe-13.36% Cr-0.37%C stainless steel for precision measuring gauge have been investigated. Type 420 stainless steel has the self-hardenability, because the nose of isothermal transformation diagram located greatly to the right. The highest hradness in the martensite martrix with undissolved carbide is obtained by oil and air cooling treatment after austenizing at 1000-1050℃, for 1/6-1/3hr. In case of low temperature tempering, internal stress is reduced without dissolution of martensite matrix, and hardness reduced slightly. In case of high temperature tempering, hardness is reduced greatly, because the martensite matrix is dissolved into a ferrite and carbide.
SKD11 冷間金型材의 熱處理에 따른 機械的 性質의 向上에 대하여
吳應源,安幸根,梁權承 조선대학교 동력자원연구소 1988 動力資源硏究所誌 Vol.10 No.2
In order to study the change of properties of SKD11 for Cold-Working Die Steel with the various heat treatment, the change of microstructures, hardness, carbide precipitations, amounts of retained austenite and impact value have been investigated. The optimum solution temperature is 1000℃ in case of oil quenching, and is 1050℃ in case of air cooling on considering impact value. In case of high-temperature tempering the hardness is not reduced greatly due to secondary hardening by carbide precipitaion. The value of Charpy impact is high in case of air cooling after holding at 1050℃ for 1/3hr. Considering the hardness and toughness, however, the air cooling after holding at 1050℃ for 1/3hr is appropriate for tool die steels. The value Charpy impact increases by 550℃ tempering treatment.
Ausformed Martensite의 擴散型 逆變態處理에 대한 熱力學的 硏究
金學信,金炳日,安幸根,柳正熙 전북대학교 공업기술연구소 1987 工學硏究 Vol.18 No.-
Thermodynamic factors of ausformed martensite and reversed austenite produced from ausformed martensite in Fe-31% Ni-0.2%C alloy have been investigated. The results obtained in this study are as follows : A_b point and A_f point of ausformed martensite increase with the increase of deformation degree when it is deformed below A_d point. The enthalpy change of the reverse martensitic transformation decreases with the increase of deformation degree but the activation energy increases with the increase of deformation degree. The change of chemical free energy of the reverse martensitic transformation is -374.5cal/mole. the calculated and observed enthalph changes of reverse martensitic transformation are 36.5J/g and 24.5J/g respectively. The strain energy produced by the reverse martensitic transformation is considered to be about 300~500cal/mole.