Microstructural Stability and Creep Performance of a Novel Low-Cost Single Crystal Superalloy

Z. H. Tan,X. G. Wang,Y. L. Du,Y. M. Li,Y. H. Yang,J. L. Liu,J. D. Liu,J. G. Li,Y. Z. Zhou,X. F. Sun 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The increasing pursuit of advanced aero-engines with lower ratio between the cost and performance has greatly promotedthe demanding of single crystal superalloys characterized by low cost and outstanding temperature capability. In this study,a novel low-cost single crystal superalloy was designed and the creep tests as well as micro-characterization were carried outon the experimental alloy. The results illustrated that the novel single crystal alloy exhibited an ideal microstructural stabilitywithout precipitating TCP phases, after long-term thermal exposure at the ultimate service temperature of third generationsingle crystal superalloys. Moreover, the experimental alloy with only 3 wt% Re addition demonstrated remarkable creepresistance and maintained a very low minimum creep rate at 1100 °C/137 MPa and 1120 °C/137 MPa, while the accumulationand coalescence of micro-pores had eventually led to the alloy fracture. Apart from that, the compact interfacial dislocationnetworks the 2nd γ′ phase were observed after high-temperature creep rupture, and the typical a < 010 > superdislocationswith relatively poor mobility was found at 1120 °C. At 760 °C/800 MPa, both the minimum creep velocity and entire creepstain was increased evidently, however, the ultimate creep rupture life of the alloy had still reached 200 h. The correspondingdeformation mechanism was identified as the combination of superdislocation pairs shearing and a/3 < 121 > partial dislocationcutting the γ′ phase with a SISF being generated. In general, the novel single crystal alloy characterized by remarkablemechanical properties and cost reduction possesses a great potential for future application in the advanced aircraft engines.

수험생활 중 경주 및 포항 지진 경험

김선주,김유영,김은주,박솔민,배지윤,이민영,이유진,정재원,Li Keying,Wuyingjinzhu,신수진,도지영 이화여자대학교 간호과학대학 2019 이화간호학회지 Vol.- No.53

Purpose: The purpose of this study was to understand the experiences of Gyeongju and Pohang earthquakes during the examinees’ life. Methods: This study applied Colaizzis’s Phenomenological method. The Data was collected through in-depth interviews with a total 8 students of university in Seoul. Results: On the analysis of the interviews, their experience can be expressed as ‘Feeling embarrassed and frightened by earthquakes’, ‘Reduced susceptibility to earthquake hazards due to heavy exam pressure’, ‘Increased exam stress due to earthquake’, ‘Feeling the inadequacy of examinees' earthquake related safety measures in retrospect’. Conclusion: This study was meaningful in deeply understanding of their experiences and revealing that the examinees were more focused on studying rather than actively coping with the disaster. Furthermore, it reconsider the social climate surrounding college admission exams. This study meaningfully discovered that examinees could not stably prepare for both the exam and the earthquake evacuation procedures due to the timing of the earthquake in relation to their upcoming college admission test. Therefore, this study highlighted the examinees’ difficulties due to the earthquakes and increased the necessity of acute phase nursing intervention in relation to the seismic safety education system.

증강화학 발광 면역법을 이용한 잡상선 홀몬 측정평가

김순기 ( S K Kim ),김용남 ( Y N Kim ),허순자 ( S Z Her ) 대한임상검사과학회 1991 대한임상검사과학회지(KJCLS) Vol.23 No.1

Whereas radioimmunoassay technique which is very sensitive as well as accurate has been widely used for the assay of most endocrinological hormones, numbers of related problems launched the search for many lab. techniques that can replace the use of radioisotopes. Authors employed "Enhanced Luminescence Immunoassay" (ELlA) technique as the one to assay and evaluate thyroid hormone(T3, T 4) and thyroid stimulating hormone( TSH). The results are as follows : 1. Precision rate was calculated by assaying T 3, T 4. TSH and 25 times repetitively at 3 diffeerent concentration for each-low, medium, high -. and so was judged excellent as the coefficient of variation(CV) was 5.6% 1.6% 3% (Low), 3.2%, 2 .1%, 1.5% (medium). 5 .0%, 3%. 1.5% (High). 2. Control serum sample with known assay value labelled as Low, Medium, High was tested for 20 times for each and the results are 0. 45ng/ml (0.36-0.5), 1.37ng/ml(l.07-2.34), 3.3ng/ml (2.34-3.5) for T 4 : 3.0,ug/dl(2.3-4.1), 9.2,ug/ dl(8.0-0.18), 15Jlg/dl(12.0-18.2) for T4: and 0 .16JLIU/ml (0 .8-0 .18), 5. 65JLIU/ml (4. 6--6. 8), 29.4JLIU/ml(20.06-3l.O)for TSH. They are all in permissable range shown in the parenthesis and close the mean value, and so was judged relatively accurate. 3. Comparison with other techniques. 1) For 27 samples of T 3, 31 T4 samples, 27 TSH samples which show different values from the assay values by radioimmunoassay technique, the slope was Y=0.99x+0.06, Y=0.98x+0.27, Y = x + 0. 04 (Y =ELlA, x =RIA) and the correlation coefficient was 0. 986, 0. 958, 0. 99 in good correlation, and so did not show any statistically appreciable difference (p < 0. 01, p < 0. 05) . 2) For comparison with IMx which is also a enzyme immunoassay technique, 25 samples of T3, 36 T4 samples, 33 TSH samples were tested. The resultant slope was Y = 0. 83x + 0 .17, Y = 0. 77 x + 1.82, Y = 0. 75x+0.10(Y =ELlA, x = IMx) and the correlation coefficient was 0. 938, 0. 869, 0. 896 in good correlation for each. Accroding to the above results Amerlite, a "Enhanced Luminescence Immunoassay" technique, may be regarded as a substitute for RIA technique and the E. 0. S method (Economy of Standard) was not only economic but also able to manipulate a large quantity speedily.

R&D Status of High-current Accelerators at IFP

J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61

High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.

Size-resolved cloud condensation nuclei concentration measurements in the Arctic: two case studies from the summer of 2008

Zá,bori, J.,Rastak, N.,Yoon, Y. J.,Riipinen, I.,Strö,m, J. Copernicus GmbH 2015 Atmospheric Chemistry and Physics Vol.15 No.23

<P>Abstract. The Arctic is one of the most vulnerable regions affected by climate change. Extensive measurement data are needed to understand the atmospheric processes governing this vulnerability. Among these, data describing cloud formation potential are of particular interest, since the indirect effect of aerosols on the climate system is still poorly understood. In this paper we present, for the first time, size-resolved cloud condensation nuclei (CCN) data obtained in the Arctic. The measurements were conducted during two periods in the summer of 2008: one in June and one in August, at the Zeppelin research station (78°54´ N, 11°53´ E) in Svalbard. Trajectory analysis indicates that during the measurement period in June 2008, air masses predominantly originated from the Arctic, whereas the measurements from August 2008 were influenced by mid-latitude air masses. CCN supersaturation (SS) spectra obtained on the 27 June, before size-resolved measurements were begun, and spectra from the 21 and 24 August, conducted before and after the measurement period, revealed similarities between the 2 months. From the ratio between CCN concentration and the total particle number concentration (CN) as a function of dry particle diameter (Dp) at a SS of 0.4 %, the activation diameter (D50), corresponding to CCN / CN = 0.50, was estimated. D50 was found to be 60 and 67 nm for the examined periods in June and August 2008, respectively. Corresponding D50 hygroscopicity parameter (κ) values were estimated to be 0.4 and 0.3 for June and August 2008, respectively. These values can be compared to hygroscopicity values estimated from bulk chemical composition, where κ was calculated to be 0.5 for both June and August 2008. While the agreement between the 2 months is reasonable, the difference in κ between the different methods indicates a size dependence in the particle composition, which is likely explained by a higher fraction of inorganics in the bulk aerosol samples. </P>

Hygrothermal stress analysis of laminated composite porous plates

Y.Z. Yüksel,Ş.D. Akbaş 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.1

This paper presents the stress analysis of a composite laminated simply supported plate with porosity under hygrothermal rising. In the displacement-strain relation of the plate structure, the first shear plate deformation theory is used. Material properties of laminas are considered as orthotropic. Three different porosity distributions are used. In the solution process, the Navier method is implemented for simply supported laminated composite plate. Non-uniform temperature and moisture rising are considered for laminated plate with three laminas. In the numerical results, the stress distributions of the laminated plate are presented and discussed for different values of moisture, temperature, stacking sequence of laminas and orientation angle of layers. The numerical results show that the hygrothermal condition is very effective in the stress behavior of laminated plates.

Thickness induced magnetic anisotropic properties of Tb-Fe-Co thin films

Yüzüak G. Durak,Yüzüak E.,Ennen I.,Hütten A. 한국물리학회 2021 Current Applied Physics Vol.29 No.-

The influence of Tb25Fe61Co14 thin film thicknesses varying from 2 to 300 nm on the structural and magnetic properties has been systematically investigated by using of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, magnetization, and magneto-optic Kerr effect microscopy measurements. Thin film growth mechanism is pursued and controlled by ex-situ X-ray refractometry measurements. X-ray diffraction studies reveal that the Tb25Fe61Co14 films are amorphous regardless of thin films thicknesses. The magnetic properties are found to be strongly related to thickness and preferred orientation. With an increase in film thickness, the easy axis of magnetization is reversed from in-plane to out-of-plane direction. The change in the easy axes direction also affects the remanence, coercivity and magnetic anisotropy values. The cause for the magnetic anisotropy direction change from in-plane to out-of-plane can be related to the preferred orientation of the thin film which depends on the large out-of-plane coercivity and plays an important role in deciding the easy axes direction of the films. According to our results, up to the 100 nm in-plane direction is dominated over the whole system under major Fe-Fe interaction region, after that point, the magnetic anisotropy direction change to the out-of-plane under major Tb-Fe/Tb-Co interaction region and preferred orientation dependent perpendicular magnetic anisotropic properties become more dominated with 2.7 kOe high coercive field values.

Numerical solution for multiple confocal elliptic dissimilar cylinders

Y. Z. Chen 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.2

This paper provides a numerical solution for multiple confocal elliptic dissimilar cylinders. In the problem, the inner elliptic notch is under the traction free condition. The medium is composed of many confocal elliptic dissimilar cylinders. The transfer matrix method is used to study the continuity condition for the stress and displacement along the interfaces. Two cases, or the infinite matrix case and the finite matrix case, are studied in this paper. In the former case, the remote tension is applied in y- direction. In the latter case, the normal loading is applied along the exterior elliptic contour. For two cases, several numerical results are provided.

Band gap engineering of ZnMnO diluted magnetic semiconductor by alloying with ZnS

Yunusov, Z.A.,Yuldashev, Sh. U.,Kwon, Y.H.,Kim, D.Y.,Lee, S.J.,Jeon, H.C.,Jung, H.,Kim, A.,Kang, T.W. North-Holland Pub. Co 2018 Journal of magnetism and magnetic materials Vol.446 No.-

<P><B>Abstract</B></P> <P>In this paper we report the results on the fabrication of diluted magnetic semiconductors Zn<SUB>1−x</SUB>Mn<SUB>x</SUB>O<SUB>1−y</SUB>S<SUB>y</SUB> thin films with manganese x=0.05 and sulfur 0≤y≤0.15 compositions, respectively, by using ultrasonic spray pyrolysis method. The influence of the sulfur concentration on the band gap energy, structural and magnetic properties have been studied by using optical transmission, X-ray diffraction and superconducting quantum interference device (SQUID) measurements, respectively. The morphology and composition of samples were studied by using Scanning Electron Microscope (SEM) and X-ray photoelectron spectroscopy (XPS). With increasing of the sulfur concentration the band gap energy of composition decreases, while the magnetization increases proportional to the sulfur concentration.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of the sulfur dopant concentration on the structural, optical and magnetic properties. </LI> <LI> Band gap energy of the films decreases from 3.2eV to 2.96eV with increasing the sulfur dopant concentration. </LI> <LI> The SQUID and Hall Effect measurements demonstrate the room temperature ferromagnetism in the sulfur doped ZnMnO thin films. </LI> </UL> </P>

Combustion synthesis and photoluminescence properties of CaAl2O4 : Eu2+, Y3+ based long lasting nanophosphors

HALEFOGLU. Y.Z. 한양대학교 세라믹연구소 2014 Journal of Ceramic Processing Research Vol.15 No.4

Phosphorescent materials are known as long lasting materials including lanthanide atom doped nano particles which recently have found wide application field. Phosphorescent, classically, is the materials which have light emission in visible region of electromagnetic spectrum on removal of excitation effect such as radiation, electron beam, electrical field, temperature etc. A novel red long lasting phosphor CaAl2O4 : Eu2+, Y3+ nano phosphors have been prepared using a combustion method. The crystallization, particle sizes and luminescence properties of the samples have been investigated systematically by using powder X-ray diffraction, scanning electron microscopy, luminescence spectrophotometer and FT-IR.