• Title/Summary/Keyword: Stacking fault

Search Result 87, Processing Time 0.036 seconds

The Influence of Vanadium Addition on Fracture Behavior and Martensite Substructure in a Ni-36.5at.%Al Alloy (Ni-36.5at.%Al 합금에서 V 첨가가 파괴거동 및 마르텐사이트 내부조직에 미치는 영향)

  • Kim, Young Do;Choi, Ju;Wayman, C. Marvin
    • Analytical Science and Technology
    • /
    • v.5 no.2
    • /
    • pp.203-211
    • /
    • 1992
  • Fracture behavior and martensite substructure of Ni-36.5at.%Al alloy were investigated with the addition of vanadium which is known as scavenging element of grain boundary. The fracture surfaces were examined by scanning electron microscopy and the EDX spectrometer was applied for composition analysis of fracture surfaces. The substructure of martensite was studied by transmission electron microscopy. By addition of vanadium, fracture surfaces show mixed modes of intergranular and transgranular fracture and more Al content is found on the grain boundaries. For Ni-36.5at.%Al alloy, the planar faults observed in the martensite plates are the internal twins. By increasing the vanadium content, the modulated structure with stacking faults and dislocations dominates while the twinned martensite disappears. The stacking fault is determined to be extrinsic due to the substitution of V for Al. It is concluded that the segregation of sulfur on the high-energy state stacking fault area suppresses the intergranular fracture.

  • PDF

Processing and Characterization of a Direct Bonded SOI using SiO$_2$ Thin Film (SiO$_2$ 박막을 이용한 SOI 직접접합공정 및 특성)

  • 신동운;최두진;김긍호
    • Journal of the Korean Ceramic Society
    • /
    • v.35 no.6
    • /
    • pp.535-542
    • /
    • 1998
  • SOI(silicon oninsulator) was fabricated through the direct bonding of a hydrophilized single crystal Si wafer and a thermally oxidized SiO2 thin film to investigate the stacking faults in silicon at the Si/SiO2 in-terface. At first the oxidation kinetics of SiO2 thin film and the stacking fault distribution at the oxidation interface were investigated. The stacking faults could be divided into two groups by their size and the small-er ones were incorporated into the larger ones as the oxidation time and temperature increased. The den-sity of the smaller ones based critically lower eventually. The SOI wafers directly bonded at the room temperature were annealed at 120$0^{\circ}C$ for 1 hour. The stacking faults at the bonding and oxidation interface were examined and there were anomalies in the distributions of the stacking faults of the bonded region to arrange in ordered ring-like fashion.

  • PDF

Transmission Electron Microscopy Study of Stacking Fault Pyramids Formed in Multiple Oxygen Implanted Silicon-on-Insulator Material

  • Park, Ju-Cheol;Lee, June-Dong;Krause, Steve J.
    • Applied Microscopy
    • /
    • v.42 no.3
    • /
    • pp.151-157
    • /
    • 2012
  • The microstructure of various shapes of stacking fault pyramids (SFPs) formed in multiple implant/anneal Separation by Implanted Oxygen (SIMOX) material were investigated by plan-view and cross-sectional transmission electron microscopy. In the multiple implant/anneal SIMOX, the defects in the top silicon layer are confined at the interface of the buried oxide layer at a density of ${\sim}10^6\;cm^{-2}$. The dominant defects are perfect and imperfect SFPs. The perfect SFPs were formed by the expansion and interaction of four dissociated dislocations on the {111} pyramidal planes. The imperfect SFPs show various shapes of SFPs, including I-, L-, and Y-shapes. The shape of imperfect SFPs may depend on the number of dissociated dislocations bounded to the top of the pyramid and the interaction of Shockley partial dislocations at each edge of {111} pyramidal planes.

The Study of Si homoepitaxial growth on Si(111) Surface (Si(111)표면 위에서 Si의 동종층상성장에 관한 연구)

  • Kwak, Ho-Weon;moon, Byung-yeon
    • Journal of the Korean Society of Industry Convergence
    • /
    • v.7 no.4
    • /
    • pp.349-354
    • /
    • 2004
  • The growth mode of the Si layers which were grown on Si(111) by using Ag as surfactant were investigated by intensity oscillations of the RHEED specular spot at the different temperatures. we found that the introduction of Ag as the surfactant alters the growth mode from a three-dimensional clustering mechanism to a two-dimensional layer-by-layer growth. In the growth of Si layers on Si(111) with a surfactant Ag, At $450^{\circ}C$, RHEED intensity oscillation was very stable and periodic from early stage of deposition to 32 ML. RHEED patterns during homoepitaxial growth at $450^{\circ}C$ was changed from $7{\times}7$ structure into ${\sqrt{3}}{\times}{\sqrt{3}}$ structures. Since the ${\sqrt{3}}{\times}{\sqrt{3}}$ structure include no stacking fault, the stacking fault layer seems to be reconstructed into normal stacking one at transition from the $7{\times}7$ structure to a ${\sqrt{3}}{\times}{\sqrt{3}}$ one. We also found that the number of the intensity oscillation of the specular spot for Si growth with a surfactant Ag was more than for Si growth without a surfactant. This result may be explained that the activation energy decrease for the surface diffusion of Si atoms due to segregation of the surfactant toward the growing surface.

  • PDF

Effect of Austenite Grain Size on Ms temperature of γ→ε Martensitic Transformation in an Fe-Mn Alloy (Fe-Mn 합금에서 γ→ε 마르텐사이트 변태의 Ms 온도에 미치는 오스테나이트 결정립크기의 영향)

  • Jun, Joong-Hwan;Choi, Chong-Sool
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.10 no.2
    • /
    • pp.93-100
    • /
    • 1997
  • Effect of austenite grain size on starting temperature of ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation($M_s$) has been studied in an Fe-18%Mn alloy. Particular attention was paid on the variation of stacking fault energy with austenite grain size, which is considered to be a important factor affecting ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation. Austenite grain size was increased in a wide range from $13{\mu}m$ to $185{\mu}m$ with increasing solution treatment temperature from $700^{\circ}C$ to $1100^{\circ}C$. Hardness was decreased with increasing austenite grain size while the volume fraction of ${\varepsilon}$ martensite showed a reverse tendency, which indicates that the hardness is more dependent on austenite grain size than ${\varepsilon}$ martensite content. No significant change was found in $M_s$ temperature when the grain size was larger than about $30{\mu}m$. In case that, the austenite grain size was smaller than about $30{\mu}m$, however, $M_s$ temperature was marlkedly decreased with decreasing austenite grain size. A linear relationship between $M_s$ temperature and the stacking fault formation probability, i.e. the reciprocal of the stacking fault energy was obtained, which suggests that the variation of $M_s$ temperature with austenite grain size is closely related to the change in stacking fault energy.

  • PDF

Effect of C, Mn and Al Additions on Tensile and Charpy Impact Properties of Austenitic High-manganese Steels for Cryogenic Applications (극저온용 오스테나이트계 고망간강의 인장 및 충격 특성에 미치는 C, Mn, Al 첨가의 영향)

  • Lee, Seung-Wan;Hwang, Byoungchul
    • Korean Journal of Materials Research
    • /
    • v.29 no.3
    • /
    • pp.189-195
    • /
    • 2019
  • The effect of C, Mn, and Al additions on the tensile and Charpy impact properties of austenitic high-manganese steels for cryogenic applications is investigated in terms of the deformation mechanism dependent on stacking fault energy and austenite stability. The addition of the alloying elements usually increases the stacking fault energy, which is calculated using a modified thermodynamic model. Although the yield strength of austenitic high-manganese steels is increased by the addition of the alloying elements, the tensile strength is significantly affected by the deformation mechanism associated with stacking fault energy because of grain size refinement caused by deformation twinning and mobile dislocations generated during deformation-induced martensite transformation. None of the austenitic high-manganese steels exhibit clear ductile-brittle transition behavior, but their absorbed energy gradually decreases with lowering test temperature, regardless of the alloying elements. However, the combined addition of Mn and Al to the austenitic high-manganese steels suppresses the decrease in absorbed energy with a decreasing temperature by enhancing austenite stability.

The Effect of Stacking Fault on Thermoelectric Property for n-type SiC Semiconductor (N형 SiC 반도체의 열전 물성에 미치는 적층 결함의 영향)

  • Pai, Chul-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.22 no.3
    • /
    • pp.13-19
    • /
    • 2021
  • This study examined the effects of stacking faults on the thermoelectric properties for n-type SiC semiconductors. Porous SiC semiconductors with 30~42 % porosity were fabricated by the heat treatment of pressed ��-SiC powder compacts at 1600~2100 ℃ for 20~120 min in an N2 atmosphere. XRD was performed to examine the stacking faults, lattice strain, and precise lattice parameters of the specimens. The porosity and surface area were analyzed, and SEM, TEM, and HRTEM were carried out to examine the microstructure. The electrical conductivity and the Seebeck coefficient were measured at 550~900 ℃ in an Ar atmosphere. The electrical conductivity increased with increasing heat treatment temperature and time, which might be due to an increase in carrier concentration and improvement in grain-to-grain connectivity. The Seebeck coefficients were negative due to nitrogen behaving as a donor, and their absolute values also increased with increasing heat treatment temperature and time. This might be due to a decrease in stacking fault density, i.e., a decrease in stacking fault density accompanied by grain growth and crystallite growth must have increased the phonon mean free path, enhancing the phonon-drag effect, leading to a larger Seebeck coefficient.

Influence of Dislocation Substructure on Ultrasonic Velocity under Tensile Deformation

  • Kim, C.S.;Lissenden, Cliff J.;Kang, Kae-Myhung;Park, Ik-Keun
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.28 no.6
    • /
    • pp.477-482
    • /
    • 2008
  • The influence of dislocation substructure of metallic materials on ultrasonic velocity has been experimentally investigated. The test materials of pure Cu, brass (Cu-35Zn), 2.25Cr-1Mo steel, and AISI 316 with different stacking fault energy (SFE) are plastically deformed in order to generate dislocation substructures. The longitudinal wave velocit $(C_L)$ decreases as a function of tensile strain in each material. The $C_L$ of Cu-35Zn and AISI 316 decreases monotonously with tensile strain, but $C_L$ of Cu and 2.25Cr-1Mo steel shows plateau phenomena due to the stable dislocation substructure. The variation of ultrasonic velocity with the extent of dislocation damping and dislocation substructures is discussed.

Crystallite Size Measurement of Uranium Oxide Fuel Powders by Neutron Diffraction (중성자 회절에 의한 산화우라늄 핵연료 분말의 결정크기 측정)

  • 류호진;강권호;문제선;송기찬;최용남
    • Journal of Powder Materials
    • /
    • v.10 no.5
    • /
    • pp.318-324
    • /
    • 2003
  • The nano-scale crystallite sizes of uranium oxide powders in simulated spent fuel were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed $UO_2$ and fission product powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The non-uniform strain, stacking fault and twin probability were measured using the information from the diffraction pattern. The realistic crystallite size could be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin.

TSV Fault Detection Technique using Eye Pattern Measurements Based on a Non-Contact Probing Method (Eye 패턴을 사용한 비접촉 형태의 TSV 고장 검출 기법)

  • Kim, Youngkyu;Han, Sang-Min;Ahn, Jin-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.64 no.4
    • /
    • pp.592-597
    • /
    • 2015
  • 3D-IC is a novel semiconductor packaging technique stacking dies to improve the performance as well as the overall size. TSV is ideal for 3D-IC because it is convenient for stacking and excellent in electrical characteristics. However, due to high-density and micro-size of TSVs, they should be tested with a non-invasive manner. Thus, we introduce a TSV test method on test prober without a direct contact in this paper. A capacitive coupling effect between a probe tip and TSV is used to discriminate small TSV faults like voids and pin-holes. Through EM simulation, we can verify the size of eye-patterns with various frequencies is good for TSV test tools and non-contact test will be promising.