• 한국재료학회지
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• 제13권5호
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• pp.292-296
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• 2003

In an attempt to enhance phase transformation and homogenization of Mn-doped $FeSi_2$, mechanical alloying of elemental powders was applied. Cold pressing and sintering in vacuum were carried out to produce a dense microstructure, and then isothermal annealing was employed to induce a phase transformation to the $\beta$-$FeSi_2$semiconductor. Phase transitions in this alloy system during the process were investigated by using XRD, EDS and SEM. As-milled powders after 100 h of milling were shown to be metastable state. As-sintered iron silicides consisted of untransformed mixture of $\alpha$-$Fe_2$$Si_{5}$and $\varepsilon$-FeSi phases. $\beta$-$FeSi_2$phase transformation was induced by subsequent isothermal annealing at $830^{\circ}C$, and near single phase of $\beta$-$FeSi_2$was obtained after 24 h of annealing. Thermoelectric properties in terms of Seebeck coefficient, and electrical conductivity were evaluated and correlated with phase transformation. Seebeck coefficient electrical resistivity and hardness increased with increasing annealing time due to $\beta$ phase transformation.

• 전자공학회논문지A
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• 제30A권1호
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• pp.23-30
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• 1993

Hydrogenation on the top gate and bottom gate Poly-Si TET's was performed by using Nh$_{3}$ plasma and annealing SiN film deposited by PECVD and then the electric characteristics on Poly-Si TET were investigated. As the time of NA$_{3}$ plasma treatment increaes, on/off current ratio gradually increases and the swing value decreases. The trap densities of graim boundaries in Poly-Si decrease very much during the inital 20min of hydrogenation time, and the decreasing scale becomes smaller after 20 min. The electric characteristics of the top gate TFT are better than those of the bottom gate TFT, it is considered due to the defects at the interface between the Poly-Si and the underlayer, SiO$_{2}$. After NH$_{3}$ plasma was treated for 2 hours for the top gate TFT, as the aging time atroon temperature increases on current was not scacely changed and off current decreases more than 1 order. Gate current density recovers to original value after the aging treatment for 8 days and then the electric characteristics are finally improved. It is suggested that the degraded characteristics of gate oxide are improved, from the variations of C-V characteristics with aging time. For the hydrogenation of isothermal and isochronal annealing SiN film deposited by PECVD, the characteristics of Poly-Si TFT are improved with increasing annealing temperature and are not largely changed with increasing annealing time. This results is good in agreement with the hydrogen reduction in Sin film as variations of annealing temperature and time.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.611-616
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• 2011

본 연구에서는 무배향 PLA 필름의 어닐링(annealing) 단계를 통하여 온도별 PLA 필름의 avrami 결정화 속도식을 도출하고 결정화 속도상수(k)를 비교함으로써 최적화된 어닐링 온도를 제안하였다. 120, 130, $140^{\circ}C$ 온도에서 결정화된 필름의 결정화 속도상수(k)는 각각 1.64, 1.68, 1.26이었다. 필름표면에 대한 어닐링은 필름의 표면조도와 동마찰계수에 영향을 주는데 80, 110, 120, 130, $140^{\circ}C$의 온도조건에서 표면조도(Ra)는 각각 0.006, 0.009, 0.015, 0.027, 0.029 ${\mu}m$로 높아졌고 동마찰계수(${\mu}_k$)는 0.45, 0.43, 0.33, 0.31, 0.27로 낮아졌다. 탈크를 1, 3, 5 wt%씩 첨가하는 경우 PLA 필름의 결정화 속도상수(k)는 0.58, 0.46, 0.39로 낮아졌다.

• 한국세라믹학회지
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• 제43권2호
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• pp.69-73
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• 2006

A full retention of the tetragonal phase with coarse grains $(50\~60\;{\mu}m)$ was possible with the specimen $ZrO_2-1.9\;mol\%\;Y_2O_3$. In these coarse grains, $\{101\}_t$ annealing twins were frequently observed, although they do not exist in the usual fine grained specimens. The morphology and growth rate of the isothermally formed individual products are studied at an optical microscopic level. The habit planes of both products are also identified by performing two-surface trace analysis on the grains whose orientations are determined by the Electron Back Scattering Pattern (EBSP) method. The morphologies of isothermal martensite were well-defined thin plates and lenticular types. The growth rate in their longitudinal directions was quite slow and temperature-dependent. A two-surface trace analysis, incorporated with the EBSP method, identified the habit planes near $\{013\}_c$, in agreement with previous reports obtained from TEM works.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.9-12
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• 2001

The microstructure evolution and the peritectic solidification of Sm$Ba_{2}$$Cu_{3}$ $O_{7-\delta}$ superconducting materials during the isothermal annealing were studied over the temperature range 1030-$1060^{\circ}C$ The faceted growth of the peritectic phase and its dependence upon Sm-diffusion in the liquid phase are discussed. A growth model is proposed to explain the growth shape of Sm123 crystals.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.263-266
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• 2009

Transformation induced plasticity (TRIP) steel consisting of ferrite, austenite, and bainite phases was regarded as an excellent candidate for automotive applications due to the good combination of ductility and strength. The aim of the present study was to understand the microstructural characteristics of ultrafine grained (UFG) TRIP low-carbon steel fabricated via equal channel angular pressing accompanied with intercritical- and isothermal-annealing treatments. When compared to coarse grained counterpart, only the volume fraction of austenite phase in UFG TRIP steel remained unchanged, but all other microstructural variables such as size and morphology were different. It was found that UFG TRIP steel showed the homogeneous distribution of each constituent phase, which was discussed in terms of annealing treatments done in this study.

• 한국세라믹학회지
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• 제30권5호
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• pp.389-396
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• 1993

We studied the crystallization behavior of amorphous PbTiO3 thin film grown at 30$0^{\circ}C$ by RF magnetron sputtering on Pt substrate. Crystallization to full perovskite phase was observed after annealing at 475$^{\circ}C$, for 9min, without PbO volatilization. The higher the annealing temperature, the shorter the time required for crystallization. The isothermal kinetic study at 475$^{\circ}C$ showed that the Avrami constant was approximately 4, which implies that the crystallization can be characterized by isotropic 3-dimensional growth with a constant nucleation rate. The TEM study revealed that the crystallized thin film was composed of very fine (20~100nm) grains oriented randomly without any evidence of 90$^{\circ}$domain boundaries.

• 열처리공학회지
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• 제11권3호
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• pp.216-226
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• 1998

Heat treatment conditions and the formation of microstructures were studied for improving the transformation-induced plasticity(TRIP) effect of retained austenite and mechanical properties of Fe-0.2%C-1.5%Si-1.5%Mn sheet steel. An excellent combination of elongation about 30% and high strength over 760MPa was achieved by processing of intercritical annealing and isothermal holding Intercritical annealing the sheet steel produced fine particles($1{\sim}2{\mu}m$) of retained austenite which were stabilized due to C enrichment by subsequent holding in bainite transformation range. Heat treatment conditions were depended on the shape and distribution of second phases as well as the volume fraction and stability of retained austenrte. In this work, the heat treatment condition of optimal strength-elongation balance was obtained by holding the steel at $400^{\circ}C$ for 200sec, after intercritical annealing at $790^{\circ}C$ for 300sec.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.143-146
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• 1996

In (GeTe)$_{100-x}$(Sb$_2$Te$_3$)$_{x}$(x=33.5, 50, 66.5, 80 at.%) thin films, the optical properties of amorphous and crystalline thin film, XRD were studied. Also, the application for the phase change optical recording materials with the high stability and rapid erasing ability were studied. In the (GeTe)$_{100-x}$(Sb$_2$Te$_{3}$)$_{x}$ the transmittance was decreased with the increase of x. In all thin films, the transmittance was decreased and the reflectance was increased by annealing and particularly, the reflectance before and after annealing showed the large reflectance ratio. The XRD pattern, it was confined that these change of optical properties was due to the crystallization of amorphous thin films. The reflectance change was investigated using isothermal annealing condition.ion.ion.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권3호
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• pp.146-152
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• 2011

Thermal stability of $Ge_2Sb_2Te_5$ (GST) and $SiO_2$ doped GST (SGST) films for phase change random access memory applications was investigated by observing the change of surface roughness, layer density and composition of both films after isothermal annealing. After both GST and SGST films were annealed at $325^{\circ}C$ for 20 min, root mean square (RMS) surface roughness of GST was increased from 1.9 to 35.9 nm but that of SGST was almost unchanged. Layer density of GST also steeply decreased from 72.48 to 68.98 $g/cm^2$ and composition was largely varied from Ge : Sb : Te = 22.3 : 22.1 : 55.6 to 24.2 : 22.7 : 53.1, while those of SGST were almost unchanged. It was confirmed that the addition of a small amount of $SiO_2$ into GST film restricted the deterioration of physical and chemical properties of GST film, resulting in the better thermal stability after isothermal annealing.