• Title/Summary/Keyword: Alloy Composition Ratio

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Thermoelectric characteristics depend on compositions of $Bi_2Te_3$ in mixed alloy with PbTe

  • Jung, Kyoo-Ho;Yim, Ju-Hyuk;Kim, Jin-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03a
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    • pp.11-11
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    • 2010
  • In order to design for nano structured materials with enhanced thermoelectric properties, the alloys in the pseudo-binary $Bi_2Te_3$-PbTe system were investigated for their micro structure and thermal properties. For this synthesis the liquid alloys were cooled by water quenching method. The micro structure images were taken by using electron probe micro analyzer (EPMA). Dendritic and lamellar structures were clearly observed with the variation in the composition ratio between $Bi_2Te_3$ and PbTe. It was confirmed that a metastable compounds is $PbBi_2Te_4$ in the The $Bi_2Te_3$-PbTe system. The change in the composition increasing $Bi_2Te_3$ ratio causes to change structure from dendritic to lamellar. Seebeck coefficient of alloys 5 which the mixture rate of $Bi_2Te_3$ is 83% was measured as the highest value. In contrast, the others decreased by increasing $Bi_2Te_3$. n-type characteristics was observed at all condition except alloy 6 which $Bi_2Te_3$ ration is 91%. The power factors of all samples were calculated with Seebeck coefficient and resistivity. Also the thermal conductivity was measured by using laser flash analyzer (LFA). In this work, the microstructures and thermal properties have been measured as a function of ratio of $Bi_2Te_3$ in the $Bi_2Te_3$-PbTe system.

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Computer-Aided Alloy Design of Insert Metal for Transient Liquid Phase Bonding of High Aluminum Ni-base Superalloys

  • Nishimotd, Kazutoshi;Saida, Kazuyoshi
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.803-808
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    • 2002
  • A computer-aided alloy-designing technique to develop the insert metal for transient liquid phase (TLP) bonding was applied to high aluminum Ni-base superalloys. The main procedure of a mathematical programming method was to obtain the optimal chemical composition through rationally compromising the plural objective performances of insert metal by a grid-search which involved data estimation from the limited experimental data using interpolation method. The objective function Z which was introduced as an index of bonding performance of insert metal involved the melting point, hardness (strength), formability of brittle phases and void ratio (bonding defects) in bond layer as the evaluating factors. The contour maps of objective function Z were also obtained applying the interpolation method. The compositions of Ni-3.0%Cr-4.0%B-0.5%Ce (for ${\gamma}$/${\gamma}$/${\beta}$ type alloy) and Ni3.5%Cr-3.5%B-3%Ti (for ${\gamma}$/${\gamma}$ type alloy) which optimized the objective function were determined as insert metal. SEM observations revealed that the microstructure in bond layers using the newly developed insert metals indicated quite sound morphologies without forming microconstituents and voids. The creep rupture properties of both joints were much improved compared to a commercial insert metal of MBF-80 (Ni-15.5%Cr-3.7%B), and were fairly comparable to those of base metals.

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Effect of Carbon on the Coefficient of Thermal Expansion of As-Cast Fe-3 0 wt.%Ni-12.5wt.% Co-xC Invar Alloys

  • 김봉서;유경재;김병걸;이희웅
    • Transactions of Materials Processing
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    • v.8 no.3
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    • pp.247-247
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    • 1999
  • The segregation (distribution) of nickel and the composition of its constituents influence the low thermal expansion characteristics (Invar effect) in Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy. The change of coefficient of the thermal expansion and magnetic properties were studied as an aspect of carbon addition causing the segregation of Ni in primary austenite of as-cast Fe-30 wt.% Ni-12.5 wt.% Co Invar alloy. The coefficient of thermal expansion of Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy showed its lowest value at 0.08 wt.% carbon, increased with increasing carbon content in the range of 0.08-1.0 wt.%C, kept constant at 1.0-2.0 wt.%C and decreased at carbon higher than 2.0 wt.%. The effective distribution of the coefficient of nickel in as-cast Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy increased with increasing carbon content. The volume fraction of they phase of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy increased with increasing carbon content. The microstructure of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy changed with the carbon content was independent of the coefficient of thermal expansion. The Curie temperature changed linearly with the carbon content and was similar to the change of the coefficient of thermal expansion. Moreover, the coefficient of thermal expansion decreased when the ratio of saturation magnetization to Curie temperature ($\sigma_s/T_c$) increased, decreasing the Curie temperature and showed a specific relationship with the magnetic properties of the Fe-30 wt.% Ni-12.5 wt.% Co-xCInvar alloy.

Phase Changes and Microstructural Properties of Ti Alloy Powders Produced by using Attrition Milling Method (어트리션 밀링법으로 제조된 티타늄합금의 상변화 및 미세조직특성)

  • Cha, Sung-Soo
    • Journal of Technologic Dentistry
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    • v.23 no.1
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    • pp.9-19
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    • 2001
  • Microstructure and phase transformation of Ti-Ni-Cu alloy powders produced by using attrition milling method were studied. Mixed powders of Ti-(50-X)Ni-XCu ($X=0{\sim}20$ at%) in composition range were mechanically alloyed for maximum 20 hours by using SUS 1/4" ball in argon atmosphere. Ball to powder ratio was 50: 1 and impeller speed was 350rpm. Mechanically alloyed with attrition millimg method. powder was heat treated at the temperature up to $850^{\circ}C$ for 1 hour in the $10^{-6}$ torr vacuum. Ti-Ni-Cu alloy powders have been fabricated by attrition milling method. and then phase transformation behaviours and microstructual properties of the alloy powders were investigated to assist in improving the the high damping capacity of Ti-Ni-Cu shape memory alloy powders. The results obtained are as follows: 1. After heat treating of fully mechanically alloyed powder at $850^{\circ}C$ for 1hour. most of the B2 and B 19' phases was formed and $TiNi_3$ were coexisted. 2. The B 19' martensite were formed in Ti-Ni-Cu alloy powders whose Cu-content is less than 5a/o. where as the B19 martensite in those whose Cu-content is more than 10at%. 3. The powders of as-milled Ti-Ni-Cu alloys whose Cu-contents is less than 5at% are amorphous. whereas those of as-milled Ti-Ni-Cu alloys whose Cu-content is more than 10at% are crystalline. This means that Cu addition tends to suppress amorphization of Ti-Ni alloy powders.

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Compositional Effect on the Magnetic Properties of Nd-Fe-Co-B and Nd-Fe-Co-Zr-B Bonded Magent (합금조성에 따른 Nd-Fe-Co-B 및 Nd-Fe-Co-Zr-B계 본드자석의 자기특성)

  • 최승덕;이우영;양충진
    • Journal of the Korean Magnetics Society
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    • v.1 no.2
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    • pp.60-68
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    • 1991
  • In compacting the melt-spun $Nd_{14}Fe_{76}Co_{4}B_{6}$ and $Nd_{10.5}Fe_{79}Co_{2}Zr_{15}B_{7}$ magnetic powders. the difference in composition induces a different behavior of closed packing rate as a function of aspect ratio of the powders. The $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy having a low Co/Fe ratio (low density) shows the better green density to have an enhanced closed packing rate. An empirical power equation relating the green density with the compacting pressure was obtained such as ${\phi}(g/cm^{2})=5.2~5.6{\times}P^{0.045~0.065}(ton/cm^{2})$. The $Nd_{14}Fe_{76}Co_{4}B_{6}$ alloy having a high Nd/Fe ratio possesses much finer grain size(50~60 nm) than that of $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy and shows the higher coercivity($iH_{c}=14~15kOe$). The higher Nd/Fe ratio in the melt-spun Nd-Fe-Co-B alloy, where the domain wall pinning mechanism was found to be predominant, assists the formation of Nd-rich grain boundary phase acting as a pinning site. The grain boundary ranges over $12~16\;{\AA}$ thick in the Nd-Fe-Co-B alloy while it ranges over $8~12\;{\AA}$ thick in the Nd-Fe-Co-Zr-B alloy.

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Restoration and Scientific Analysis of Casting Bronze Type in Joseon Dynasty (조선왕실 주조 청동활자의 복원과 과학적 분석)

  • Yun, Yong-Hyun;Cho, Nam-Chul;Lee, Seung-Cheol
    • Journal of Conservation Science
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    • v.25 no.2
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    • pp.207-217
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    • 2009
  • After replicating 10 bronze types such as Gyemija, Gyeongjaja, Eulhaeja, etc. before the Imjin war, we studied the change of microstructure from each casting process, method, and alloy ratio by Gyechukja replicated from "Donggukyeojiseungnam". We selected the average of compositions of Eulhaeja in the National Museum of Korea as the standard(Cu 86.7%, Sn: 9.7%, Pb: 2.3%) of bronze types, so we decided on the alloy's composition of Cu 87%, Sn 15%, Pb 8% added to 5% Sn and Pb contents because of evaporating the Sn and the Pb. Before replicating major metal types, we made master-alloy first, melting it again, and then replicated metal types. The composition of the 1'st replicated Gyechukja showed the range of Cu 85.81~87.63%, Sn 9.27~10.51%, Pb 3.05~3.19%. The 2'nd replicated Gyechukja made using the branch metal left after casting the 1st replica. The 2nd replicated Gyechukja showed the composition range of Cu 87.21~88.09%, Sn 9.06~9.36%, Pb 2.80~3.05%. This result decreases a little contents of Sn and Pb as compared with metal types of the 1st replica. However, it's almost the same as the Eulhaeja's average composition ratio in the National Museum of Korea. As a result of observing the microstructure of restored Gyechukja, it showed the dendrite structure of the typical casting structure and the segregation of Pb. There is no big difference of microstructure between the 1st and the 2nd restored metal types, even though the 2nd restored types partially decreases the eutectoid region in comparison with the 1st types. The systematic and scientific restoration experiment of metal types using Joseon period will be showed the casting method and alloy ratio, and this will be of great help to the study of restoration metal types in the future.

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Jangdo(Small Ornamental Knives) manufacturing process and restoration research using Odong Inlay application (오동상감(烏銅象嵌)기법을 활용한 장도(粧刀)의 제작기술 및 복원연구)

  • Yun, Yong Hyun;Cho, Nam Chul;Jeong, Yeong Sang;Jang, Chu Nam
    • Korean Journal of Heritage: History & Science
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    • v.49 no.2
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    • pp.172-189
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    • 2016
  • In this research, literature research on the Odong material, mixture ratio, casting method and casting facility was conducted on contemporary documents, such as Cheongong Geamul. Also, a long sword was produced using the Odong inlay technique. The sword reproduction steps were as follows; Odong alloying, silver soldering alloying, Odong plate and Silver plate production, hilt and sheath production, metal frame and decorative elements, such as a Dugup (metal frame), production, Odong inlay assembly and final assembly. For the Odong alloy production, the mixture ratio of the true Odong, which has copper and gold ratio of 20:1, was used. This is traditional ratio for high quality product according to $17^{th}$ century metallurgy instruction manual. The silver soldering alloy was produced with silver and brass(Cu 7 : Zn 3) ratio of 5:1 for inlay purpose and 5:2 ratio for simple welding purpose. The true Odong alloy laminated with silver plate was used to produce hilt and sheath. The alloy went through annealing and forging steps to make it into 0.6 mm thick plate and its backing layer, which is a silver plate, had the matching thickness. After the two plates were adhered, the laminated plate went through annealing, forging, engraving, silver inlaying, shaping, silver welding, finishing and polishing steps. During the Odong colouring process, its red surface turns black by induced corrosion and different hues can be achieved depending on its quality. To accomplish the silver inlay Odong techniques, a Hanji saturated with thirty day old urine is wrapped around a hilt and sheath material, then it is left at warm room temperature for two to three hours. The Odong's surface will turn black when silver inlay remains unchanged. Various scientific analysis were conducted to study composition of recreated Odong panel, silver soldering, silver plate and the colouring agent on Odong's surface. The recreated Odong had average out at Cu 95.57 wt% Au 4.16wt% and Cu 98.04 wt% Au 1.95wt%, when documented ratio in the old record is Cu 95wt% and Au 5wt%. The recreated Odong was prone to surface breakage during manufacturing process unlike material made with composition ratio written in the old record. On the silver plate of the silver and Odong laminate, 100wt% Ag was detected and between the two layers Cu, Ag and Au were detected. This proves that the adhesion between the two layers was successfully achieved. The silver soldering had varied composition of Ag depending on the location. This shows uneven composition of the silver welding. A large quantities of S, that was not initially present, was detected on the surface of the black Odong. This indicates that presence of S has influence on Odong colour. Additional study on the chromaticity, additional chemical compounds and its restoration are needed for the further understanding of the origin of Odong colour. The result of Odong alloy testing and recreation, Odong silver inlay long sword production, scientific analysis of the Odong black colouring agent will form an important foundation of knowledge for conservation of Odong artifact.

Effect of Alloying Elements of Mn and Ni on the Pitting Corrosion Resistance of 22Cr Lean Duplex Stainless Steel (22Cr 린 듀플렉스 스테인리스강의 공식저항성에 미치는 Mn과 Ni 첨가의 영향)

  • Ahn, Y.S.;Bae, K.K.
    • Journal of Power System Engineering
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    • v.16 no.5
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    • pp.76-82
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    • 2012
  • Duplex stainless steels have the dual microstructure of austenite and ferrite phases. This steel exhibits generally a high corrosion resistance and higher mechanical strength compared with austenitic stainless steels. The steels used in the investigation have the chemical composition of Fe-22Cr-xNi-yMn-0.2N in which the contents of Ni and Mn were varied with maintaining the equal [Ni/Cr] equivalent. The fraction of ferrite phase was increased with the increase of annealing temperature. The impact factor of Mn element on the [Ni] equivalent was amended on the basis of the results of the investigation. 4Mn-2Ni alloy showed the highest pitting corrosion resistance. The fraction ratio, grain size and misorientation angle between grains were measured, and the correlation with pitting potential was investigated.

Variation of Asymmetric Hysteresis Loops with Chemical Composition of Amorphous Ferromagnetic Alloys (비정질 자성 합금의 조성에 따른 비대칭 자기 이력 곡선의 변화)

  • 신경호;민성혜;이장로
    • Journal of the Korean Magnetics Society
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    • v.5 no.4
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    • pp.261-268
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    • 1995
  • In order to investigate the origin of the asymmetric magnetization reversal effect, we studied the variation of magnetic hysteresis loops with the alloy composition in amorphous ferromagnetic alloy ribbons of ${(Fe_{1-x}Co_{x})}_{75}Si_{10}B_{15}$ system annealed at $380^{\circ}C$ for 16 hours in a zero field condition. The asymmetric magnetization reversal effect developed more strongly in amorphous ribbons having two metallic components than in ribbons having a single metallic component. The effect developed more strongly in ribbons showing a smaller value of the saturation mag¬netostriction. The development of the asymmetric magnetization reversal effect was affected by the ratio of two metallic components as well as the magnitude of the saturation magnetostriction.

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A Study on the Anisotropy of Al 7075 Rolling Material in Fatigue Crack Growth Process (Al 7075 압연재의 피로균열 성장과정에서의 이방성에 관한 연구)

  • 최병기
    • Journal of the Korean Society of Safety
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    • v.14 no.2
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    • pp.19-25
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    • 1999
  • The research has extracted two kinds of specimen, one is rolling direction material(R-material) and the other rectangular of rolling direction(V-material), from Al alloy 7075 rolled. We have come to a conclusion by measuring crack propagation behavior with movement type microscope and Replica. 1) R-material shows 130% higher, approx. 39.2MPa in fatigue strength than V-material, approx. 29.4MPa. 2) In crack proportion, contrary to V-material growing directly toward specimen axis, R-material grows neared to shear direction. 3) The life proves that R-material is approx. 122% higher than V-material at 43.1MPa and approx. 135% higher at 47MPa. 4) The correlation between fatigue crack length and fracture life ratio applied to 'log(2a)=A+B ($N/N_f$)'equation shows inappropriate, because property value of Al alloy is low and the difference of chemical composition is high comparing with steel material.

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