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Fe-Mn계 합금에서 응력유기 ε 마르텐사이트의 양에 미치는 열처리 온도의 영향
지광구 ( K. K. Jee ),한주현 ( J. H. Han ),장우양 ( W. Y. Jang ) 한국열처리공학회 2004 熱處理工學會誌 Vol.17 No.6
N/A In this work, a new method of measuring volume fraction of deformation-induced ε martensite is pro-posed using endothermic heat on reverse transformation. As grain size increases, the amount of ε martensite forming on cooling increases. However, with a decrease in grain size, more ε is induced by deformation, improving shape memory effect.
Ni-Al 계 마르텐사이트 합금에서 Llo → Ni5Al3 변태
지광구(K. K. Jee),송시연(S. Y. Song),장우양(W. Y. Jang) 한국열처리공학회 2002 熱處理工學會誌 Vol.15 No.2
N/A LI_0 → Ni_5Al_3 reordering and related properties in Ni-Al alloys consisting of 64-65at%Ni are characterized by X-ray diffraction, shape memory effect and damping capacity. Formation of Ni_5Al_3 takes place by simple ordering of atoms with a continuous increase in c/a ratio. As a result, degradation of shape memory effect and damping capacity is observed after short time annealing at 200-300℃.
Fe-18wt%Mn 마르텐사이트 합금에서 주조상태와 열처리한 상태의 기계적 성질과 진동감쇠능에 관한 연구
백승한,김정철,지광구,신명철,최종술 ( S . H . Baik,J . C . Kim,K . K . Jee,M . C . Shin,C . S . Choi ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.3
In recent work, we reported that a hot-rolled Fe-18wt%Mn alloy exhibited high damping capacity as well as excellent mechanical properties. It was also proposed that damping capacity of the alloy was proportional to the γ/ε boundary area. In the present study, the effects of homogenization(12hrs at 1100℃) and solution treatment(1hr at 1050℃ before air cooling) on damping capacity and mechanical properties were investigated for as-cast and heat treated Fe-18wt%Mn alloy. The specimen subjected to both homogenization and solution treatment was found to show superior damping capacity and mechanical properties to the as-cast state due to removal of segregation and increase in γ/ε boundary area.
Fe-17wt%Mn 합금의 진동감쇠능 , 내후성 및 기계적 성질에 미치는 Cu 첨가의 영향
백승환,김정철,지광구,최종술 ( S . H . Baik,J . C . Kim,K . K . Jee,C . S . Choi ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.2
We have reported that an Fe-17wt%Mn alloy exhibits the highest damping capacity in the Fe-Mn binary system. In the present work, the effects of copper content on the damping capacity, atmospheric corrosion and mechanical properties were studied. The damping capacities were measured at room temperature for the air cooled Fe-17wt%Mn alloy having copper content from 0.1wt% to 1.1wt%. The damping capacity of the Fe-17wt%Mn alloy was decreased with increasing copper content. However, the addition of Copper was found to improve mechanical properties and atmospheric corrosion resistance. These mechanical properties were attributed to the formation of stress-induced martensite during tensile test.
논문 : 상변태 ; Fe-32Mn-6.5Si 합금에서 형상기억효과 및 변태거동에 미치는 미세조직의 영향
이지영 ( J. Y. Lee ),지광구 ( K. K. Jee ),최종술 ( C. S. Choi ),장우양 ( W. Y. Jang ),신명철 ( M. C. Shin ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
The objective of this study is to investigate the effect of microstructure and pre-strain on shape memory effect(SME) and transformation behavior in an Fe-32Mn-6.5Si alloy. The alloy was annealed at various temperatures from 600 to 1200℃ for 1 hour to vary microstructure after cold rolling. Shape memory effect and reverse transformation behavior were examined through bending test and TMA after deforming the alloy with various degrees of pre strain Austenite grain size increases with an increase in heat treatment temperature, except the specimen heat-treated at 600℃, which remains unrecrystallized. The specimen heat-treated at 600℃, retaining cold rolling effect, exhibits the best SME due to a high Md temperature. In the recrystallized specimens, the larger grain size, the better SME. As grain size increases, the reverse transformation range becomes shorter, indicating that reverse transformation takes place with less constraint. The better SME in a large grain size can be attributed to the easiness of the reverse transformation.