• 한국전기전자재료학회논문지
• /
• 제12권1호
• /
• pp.27-34
• /
• 1999

We investigated the effect of mechanical back side damage in viewpoint of electrical and surface morphological characteristics in Czochralski silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductance decay technique, atomic force microscope, optical microscope, wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage degree, the lower the minority carrier lifetime, and surface roughness, damage depth and density of oxidation induced stacking fault increased proportionally.

• Tribology and Lubricants
• /
• 제16권5호
• /
• pp.389-394
• /
• 2000

Scanning Probe Microscope (SPM) such as Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AEM) was shown to be the powerful tool for nano-scale characterization of material surfaces. Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform, and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1999년도 PROCEEDINGS OF KACG FALL MEETING, SEOUL, 4 DECEMBER, 1999
• /
• pp.1-25
• /
• 1999

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 1999년도 제16회 학술발표회 논문개요집
• /
• pp.135-135
• /
• 1999

• 한국재료학회지
• /
• 제5권7호
• /
• pp.858-868
• /
• 1995

다른 탄소함량을 갖는 두 Hadfield 강에서 압연에 따른 결정방위조직(Texture)과 마르텐사이트 상변태를 연구하였다(0.65wt.%, 1.35wt.%) 두 Hadfield 강의 적층결함에너지 차이가 매우 적음에도 불구하고 (약 2mJm$^{-2}$ ) 결정방위조직은 차이를 보였다. 0.65wt.% 탄소 강의 경우, 낮은 변형구간에서는 낮은 적층에너지 금속과 비슷한 결정방위조직을 보였으나 높은 변형에서는 {111}, {110}<001>과 같은 이상 결정방위조직이 나타났고, 이것은 입계 또는 일단의 전단띠에(shear bands) 형성된 $\alpha$ 마르텐사이트의 방해에 의한 것으로 생각된다. 이와는 대조적으로 1.35wt.% Hadfield강은 전변형구간에서 낮은 적층결함에너지를 갖는 금속과 비슷한 결정방위조직을 보이고 있다. 이것은 변형중에 유도된 마르텐사이트의 양이 적게 형성되는 사실에 기인하며, 변형에 따른 $\alpha$ 마르텐사이트 변태는 교류자화율과 금속입자 시험으로 알 수 있다.

• 한국재료학회지
• /
• 제19권8호
• /
• pp.447-451
• /
• 2009

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.

• 자원환경지질
• /
• 제45권2호
• /
• pp.181-188
• /
• 2012

일라이트에서 적층방식을 달리하여 나타나는 폴리타입은 대부분 1M과 $2M_1$이며, 적층 Disordering에 따른 $1M_d$ 또한 흔히 관찰된다. 본 해설에서는 일라이트의 폴리타입을 구분하고 정량적으로 해석할 수 있는 광물학적 이론적 근거와 방법을 소개하고, 소규모 열수환경에 준하는 단층대 내 생성시기 및 조건을 달리하는 일라이트 폴리타입 혼합물에의 적용을 통한 단층 활동 및 재활동연대 결정에의 활용 가능성을 검토하였다. 단층연대해석의 정확도와 신빙도를 높이기 위해서는 단층암 대상시료 내 일라이트 폴리타입의 생성환경에 대한 정보, 동정 및 광물학적 특성에 대한 규명이 이루어져야 한다. 또한 WILDFIRE(C)시뮬레이션을 이용한 정량분석에서, $1M_d$ 폴리타입의 Disordering 정도 및 I/S 광물의 팽창도에 기인한 (hkl) 회절선들의 Broadening 효과 등 일라이트 폴리타입 정량분석법의 오차요인을 최소화시키는 하기 방법을 고려해야 할 것이다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제3권1호
• /
• pp.40-44
• /
• 2001

Recently. the high-tc superconducting fault col-rent limiters (SFCL) are studied worldwide to be classified as a resistive type or an inductive type such as a magnetic shielding type and a inductive type. The high-tc SFCL wish an open core belongs to the magnetic shielding type SFCL. Unlike conventional magnetic shielding type SFCLS it uses the open core to reduce the mechanical vibrations and installation space, The high-tc SFCL with an open core was designed and manufactured by stacking three BSCCO 2212 tubes. It was tested in the maximum source voltage of 400 Vrms. The results such as the reduction of fault current and impedance of the SFCL are described in this paper. The results show that the fault current in the source voltage of 400 Vrms was reduced to be about 123 Apeak. about 3.9 times greater than the normal state current. Also, the impedance of the high-tc SFCL was about 9${\Omega}$ about 9 times greater than the normal state impedance. The impedance of the SFCL appears just after the fault, and its size is dependent on the source voltage. From the impedance, the inductance of the SFCL was calculated.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1999년도 제29회 춘계학술대회
• /
• pp.67-72
• /
• 1999

Scanning probe Microscope(SPM) such as Scanning Tunneling Microscope(STM) and Atomic Force Microscope(AFM) was shown to be the powerful tool for nano-scale characterization of material surfaces Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform. and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• 한국재료학회지
• /
• 제26권6호
• /
• pp.325-331
• /
• 2016

This paper presents a study of the tensile properties of austenitic high-manganese steel specimens with different grain sizes. Although the stacking fault energy, calculated using a modified thermodynamic model, slightly decreased with increasing grain size, it was found to vary in a range of $23.4mJ/m^2$ to $27.1mJ/m^2$. Room-temperature tensile test results indicated that the yield and tensile strengths increased; the ductility also improved as the grain size decreased. The increase in the yield and tensile strengths was primarily attributed to the occurrence of mechanical twinning, as well as to the grain refinement effect. On the other hand, the improvement of the ductility is because the formation of deformation-induced martensite is suppressed in the high-manganese steel specimen with small grain size during tensile testing. The deformation-induced martensite transformation resulting from the increased grain size can be explained by the decrease in stacking fault energy or in shear stress required to generate deformation-induced martensite transformation.