http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
등통로각압축공정으로 가공된 Cu-Ag 나노복합재 내의 변형쌍정
이갑호 ( Kap Ho Lee ),홍순익 ( Sun Ig Hong ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.8
The nanostructure of a Cu-15wt%Ag composite processed by Equal Channel Angular Pressing (ECAP) was observed by transmission electron microscopy (TEM). ECAP was found to greatly improve the yield strength while maintaining good electrical conductivity. The nanostructured Cu-15 wt%Ag composite contained a high density of {111}/<112> nanotwins and the migration of the twin boundary and detwinning process of those nanotwins was also observed. Nanotwins can be nucleated by bowing out of twinning dislocations at the Cu/Ag interface and propagated by the sequential emission of twinning dislocations on every adjacent twinning plane. Steps having the height of one or three atomic layers on the {111} plane were observed on the coherent twin boundary (CTB). The stair rod dislocation was formed by a cross-slip of 30° partial at one layer high step on the twin boundary, while a cross-slip of 90° partial transformed the incident dissociated dislocation into dissociated dislocation in the twin plane without leaving a stair-rod dislocation behind. The three layer high step was formed by migration of the (111) twin boundary in the direction normal to the twin plane, and it produced a {112} incoherent twin boundary (ITB). The advance or retreat of {112} ITB can lead to the extension or retraction of (111) on the CTB. The detwinning process involves the collective glide of a group of three Shockley partial with different Burgers vectors and the dynamical overlap of stacking faults (SFs) of intrinsically and/or extrinsically dissociated dislocations. †(Received January 7, 2013)
곽호연 ( Ho Yeon Kwak ),홍순익 ( Sun Ig Hong ),이갑호 ( Kap Ho Lee ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.12
The microstructure of Cu-24 wt.%Ag filamentary nanocomposite fabricated by a thermo-mechanical process has been investigated by transmission electron microscopy (TEM) observations. This study is focused on the stability of Ag filaments formed by cold drawing; the effects of thermal treatment on the precipitation behavior and distribution of Ag-rich precipitates were also investigated. The Ag filaments elongated along the <111> orientation were observed in Cu-rich α phase of the as-drawn specimen and the copper matrix and the silver filament have a cube on cube orientation relationship. Annealing at temperatures lower than 200℃ for the as-drawn specimen caused insignificant change of the fibrous morphology but squiggly interfaces or local breaking of the elongated Ag filaments were easily observed with annealing at 300℃. When samples were annealed at 400℃, discontinuous precipitation was observed in supersaturated Cu solid solution. Ag precipitates with a thickness of 7-20 nm were observed along the <112> direction and the orientation relationship between the copper matrix and the Ag precipitates maintained the same orientation relationship in the as-drawn specimen. The interface between the copper matrix and the Ag precipitates is parallel to {111} and micro-twins were observed in the Ag precipitates.
Mg-Zn-Y(ZW61) 합금에서 Icosahedral 준결정상의 석출
곽호연,이갑호,Kwak, Ho-Yeon,Lee, Kap-Ho 한국재료학회 2011 한국재료학회지 Vol.21 No.3
Precipitation of the ordered icosahedral quasicrystal in Mg-6wt%Zn-1wt%Y alloy has been characterized by transmission electron microscopy observations. The lamellar-type icosahedral qusicrystal phases (I-phase) with the face-centered icosahedral (FCI) structure are observed in alloy after solution treatment at $550^{\circ}C$. In the alloy annealed at $400^{\circ}C$, polygon-shaped I-phases are observed in the ${\alpha}$-Mg matrix. The interfaces of the I-phase with the matrix are facetted and the facets are on five-fold and two- fold plane of the I-phase. The orientation relationship of the I-phase with the matrix is determined to be $[I5]_I//[001]_{Mg}$, $(2f)_I//(2\overline{1}0)_{Mg}$ and $[I2]_I//[311]_{Mg}$, $(5f)_I//(0\overline{1}1)_{Mg}$. The icosahedral grains are occasionally found to be twinned with one of the five-fold axis as the twin axis. The twin boundaries appear to be fairly straight and perpendicular to the fivefold twin axis. The icosahedral twin can be expressed as a rotation of $63.4^{\circ}$ or $116.62^{\circ}$ around two fold zone axis.
김정,이갑호,홍순익,Kim, Joung,Lee, Kap-Ho,Hong, Sun-Ig 한국재료학회 2005 한국재료학회지 Vol.15 No.11
The ultrastructure ore of a nanostructured apatite film nucleated from solution was studied to gain insights into that of bone minerals which is the most important constituent to sustain the strength of bones. Needle-shaped apatite crystal plates with a bimodal size distribution $(\~100\;to\;\~1000 nm)$ were randomly distributed and they were found to grow parallel to the c-axis ([002]), driven by the reduction of surface energy. Between these randomly distributed needle-shaped apatite crystals which are parallel to the film, apatite crystals (20-40nm) with the normal of the grains quasi-perpendicular to the c-axis were observed. These observations suggest that the apatite film is the interwoven structure of apatite crystals with the c-axis parallel and quasi-perpendicular to the fan. In some regions, amorphous calcium phosphate, which is a precursor of apatite, was also observed. In the amorphous phase, small crystalline particle with the size of 2-3 nm were observed. These particles were quite similar, in size and shape, to those observed in the femoral trabecular bone, suggesting the nucleation of apatites by a biomimetic process in vitro is similar to that in vivo.
고분해능 전자현미경을 이용한 Mg-6 wt%Zn-1 wt%Y 합금의 석출거동에 관한 연구
백상열,이갑호,김택수,Baek, Sang-Yeol,Lee, Kap-Ho,Kim, Taek-Soo 한국재료학회 2008 한국재료학회지 Vol.18 No.7
The precipitation behavior in Mg-6 wt%Zn-1 wt%Y alloy annealed at different temperatures of $200^{\circ}C$ and $400^{\circ}C$ has been characterized by high resolution transmission electron microscope. When the alloy is annealed at $200^{\circ}C$ for 6 hr, the plate- and the rod-shaped ${\beta}_2'$ phases are precipitated in the matrix. The orientation relationship of plate-shaped precipitates with the matrix exhibits a [$11{\bar{2}}0]{\beta}_2$ || [$10{\bar{1}}0$]Mg, $(0001){\beta}_2'$ || (0001)Mg. While the rod-shaped precipitates have two kinds of the orientation relationships with the matrix, i.e. $[11{\bar{2}}0]{\beta}_2'$||[0001] Mg, $(0001){\beta}_2'||(11{\bar{2}}0)$ Mg and $[11{\bar{2}}0]{\beta}_2'$||[0001] Mg, $({\bar{1}}106){\beta}_2'||(10{\bar{1}}0)$ Mg. With increasing annealing time at $200^{\circ}C$ the ${\beta}_1'$ phases are also precipitated in the matrix and the orientation relationship exhibits a $[010]{\beta}_1'$ || [0001]Mg, $(603){\beta}_1'$ || ($01{\bar{1}}0$)Mg between the ${\beta}_1'$ precipitate and the matrix. The icosahedral phases are precipitated in the alloy annealed at $400^{\circ}C$ and exhibit a $[I2]_I$ || [0001]Mg relationship with the matrix.
N-형 Bi2 (Te0.95 Se0.05)3 열전 화합물의 구조적 변조 특성
윤성호 ( Sung Ho Yoon ),이갑호 ( Kap Ho Lee ),홍순직 ( Soon Jik Hong ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.2
An n-type Bi2Te3 thermoelectric compound was analyzed by using a high resolution transmission electron microscopy, and was further analyzed by using an image processing unit. A sinusoidal strain contrast of the structural modulations appeared in a multi-beam image and the fringes showed a wavelength of 12 nm with a wave vector parallel to the {101.10} planes. A numerous dislocations were found to glide on to the (0001) plane with a Burgers vector of 1/3<21.1.0>-type on the strain field. In order for the elastic strain energy to be relieved, the resultant 1/3<21.1.0>-type dislocation was thought to be dissociated into two partial dislocations gliding on the {1.015} planes. The variation in stacking periodicity of the 5-layers lamellar structure with respect to the basal plane of Bi2Te3 was also observed locally. However, this stacking variation is not responsible for the formation of structural modulations. The displacement of the sinusoidal strain field on the structural modulations seems to be generated by dislocation, with presence of dipoles that are about a few nanometers apart. It is understandable that phonons should be scattered throughout the strain field of the structural modulation. Hence, the lattice thermal conductivity is expected to be decreased due to the phonon scattering on sinusoidal strain field of the structural modulations.
수정된 유사체액 내에서 티타늄에 생성된 아파타이트의 고분해능 전자현미경에 의한 분석
김현욱,김우정,이갑호,홍순익,Kim, Hyun-Ook,Kim, Woo-Jeong,Lee, Kap-Ho,Hon, Sun-Ig 한국재료학회 2007 한국재료학회지 Vol.17 No.8
Process of the hydroxyapapite(HA) precipitation on bioactive titanium metal prepared by NaOH in a modified-simulated body fluid(mSBF) was investigated by high resolution transmission electron microscope (HRTEM) attached with energy dispersive X-ray spectrometer(EDX). The amorphous titanate phase on titanium surface is form by NaOH treatment and an amorphous titanate incorporated calcium and phosphate ions in the liquid to form an amorphous calcium phosphate. With increasing of soaking time in the liquid, the HA particles are observed in amorphous calcium phosphate phase with a Ca/P atomic ratio of I.30. The octacalcium phosphate (OCP) structure is not detected in HRTEM image and electron diffraction pattern. After a long soaking time, the HA particles grow as needle-like shape on titanium surface and a large particle-like aggregates of needle-like substance were observed to form on titanium surface within needle-like shape. A long axis of needle parallels to c-direction of the hexagonal HA structure.
급속응고 분말법으로 제조된 Mg<sub>97</sub>Zn<sub>1</sub>Y<sub>2</sub> 합금의 장주기 구조와 적층결함
박은기,김우정,김택수,이갑호,Park, Eun-Kee,Kim, Woo-Jung,Kim, Taek-Soo,Lee, Kap-Ho 한국재료학회 2009 한국재료학회지 Vol.19 No.8
The long-period stacking order (LPSO) structures and stacking faults (SFs) in rapidly solidified powder metallurgy (RS P/M) $Mg_{97}Zn_1Y_2$ alloy were investigated by high resolution transmission electron microscopy (HRTEM) observations. The 18R-type LPSO structure with a stacking sequence of ACBCBCBACACACBABAB and a period of 4.86 nm was observed in the as-extruded RS P/M $Mg_{97}Zn_1Y_2$ alloy. After annealing at 773 K for 5 hr, the 18R-type LPSO structure was transformed to the 14H-type LPSO structure with a stacking sequence of ABABABACBCBCBC and a period of 3.64 nm. The 24R-type LPSO structure containing 24 atomic layers of ABABABABCACACACABCBCBCBC with period of 6.18 nm coexists with the 14H-type LPSO structure in the same grains. The LPSO structures contain intrinsic Type II SFs such as BCB/CABA and ABA/CBCB stacking sequences of a closely packed plane.