• Title/Summary/Keyword: Zr-base alloys

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Surface Reaction between Phosphate bonded $SiO_2$ Investment and Ti-Zr-(Cu) based Alloys for Dental castings (인산염계 $SiO_2$ 주형재와 치과주조용 Ti-Zr-(Cu)계 합금의 계면반응)

  • Joo, Kyu-Ji
    • Journal of Technologic Dentistry
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    • v.27 no.1
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    • pp.57-63
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    • 2005
  • Experimental Ti-13%Zr and Ti-13%Zr-5%Cu alloys were made in an argon-arc melting furnace. The grade 2 CP Ti was used to control. To investigate the surface reaction layers produced by the reaction with mold materials and the influence of the reaction layers on the hardness of castings, A phosphate bonded $SiO_2$ base investment was used as mold material, and microstructure observation and hardness test were performed. The surface reaction layers of Ti-13%Zr and Ti-13%Zr-5%Cu alloys were thinner than that of CP Ti had a clearly multiple structure. A difference of the hardness between surface and inner of the Ti-13%Zr and Ti-13%Zr-5%Cu alloys became less than that of CP Ti. From the results, it was found that the Ti-Zr-(Cu) based alloys were possible to cast with $SiO_2$ base investment without the great changes of mechanical properties of the castings.

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Mechanical Properties of Al-Ti Base Alloys Processed Via Rapid Solidification and Mechanical Alloying (급냉응고 및 기계적 합금화된 Al-Ti계 합금의 기계적 성질)

  • 최철진
    • Journal of Powder Materials
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    • v.2 no.1
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    • pp.36-43
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    • 1995
  • Rapidly solidified and mechanically alloyed Al-Ti base alloys were prepared by gas atomization and attritor milling separately. The gas atomized and the mechanically alloyed powders were consolidated after preheating at $450^{\circ}C$, and then heat treated isochronally for 1 hour to observe the microstructures and to investigate the mechanical properties. Stable phases of precipitates in the Al-Ti-Si and the Al-Ti-Zr alloys were identified as DO22-$(Al,Si)_3Ti$ and $Do_{23}-Al_3(Ti, Zr)$ each. Among the alloys, the mechanically alloyed Al-l0Ti-2Si alloy showed superior thermal stability and mechanical properties at elevated temperature. The additions of third elements, such as Si and Zr, to Al-Ti alloys seemed to improve the mechnical properties remarkably by stabilizing the microstructure and the precipitate phases in the consolidated alloys.

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Precipitation Behaviors of Rapidly Solidified and Hot Worked Al-Zr Base Alloys (급냉응고 및 열간가공된 Al-Zr계 합금의 석출거동)

  • Park, Won-Wook
    • Journal of Korea Foundry Society
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    • v.15 no.2
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    • pp.194-200
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    • 1995
  • Rapidly Solidified (RS) Al-Zr base splats with various alloy contents were prepared by atomization-splat quenching method to understand the continuous and discontinuous precipitation in the aged alloys. And the RS alloys were consolidated by hot extrusion and swaging to analyze the effect of plastic deformation on the precipitation behavior. Discontinuous precipitation dominated at relatively low temperature in the Al-Zr alloy, whereas both V additions to Al-Zr alloys and hot metal working appeared to suppress the discontinuous precipitation. As continuous precipitation is favored in the grain interiors, the driving force for discontinuous precipitation become to disappear with a further process.

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Effects of Zr, B and P Additions the Grain Refinement of CuZn36 Alloys. (CuZn36 합금의 입자 미세화에 미치는 Zr, B, P 첨가의 영향)

  • Kim, Chung-Keun;Lee, Dong-Woo
    • Journal of Korea Foundry Society
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    • v.13 no.2
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    • pp.168-174
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    • 1993
  • It has been known that the grain refinement of Cu base alloys greatly improved mechanical properties, castability, workability and hot shortness resistance etc. In this study CuZr50, CuP7, CuFe7, CuMg10 binary alloys were added as grain refiners in CuZn36 alloy. The alloys melted in vacuum and controlled in mixed gas conditions and casted at $1050^{\circ}C$. Zr-P-X compound has significantly grain refined but oxygen has been found detrimental to grain refinement. In the case of Zr /B ratio below 4, B acted as grain growth element in this alloy.

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Study on the Recovery and Recrystalligation of Cold-lolled Zr-based Alloys by Thermoelectric Power Measurement During Isothermal Annealing (TEP 분석을 이용한 냉간가공된 Zr-based 합금의 등온열처리에 따른 회복 및 재결정 거동에 관한 연구)

  • O, Yeong-Min;Jeong, Heung-Sik;Kim, Seon-Jin
    • Korean Journal of Materials Research
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    • v.11 no.6
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    • pp.483-491
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    • 2001
  • The recovery and recrystallization behavior of cold-rolled Zr-based alloys during isothermal annealing at temperatures from $575^{\circ}C$ to $650^{\circ}C$ was studied by thermoelectric power and Vickers microhardness measurement. The recovery and recrystallization resulted in the increase of TEP doe to the extinction of lattice defect, vacancy, dislocation and stacking fault during isothermal annealing after cold- rolling. The completion of recrystallization could be determined much clearly by TEP behavior than by microhardness change in Zr-based alloys. Especially, the recovery and recrystallization were classified separately by TEP behavior in Zr-0.4Nb-xSn alloys. From the analysis of TEP behavior and microhardness, the addition of Sn caused to form the interaction between stain field and dislocation, which resulted in the delay of recovery in Zr-based alloys. The precipitation due the addition of Nb suppressed the grain growth after recrystallization effectively in Zr-based alloys.

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A Study on the Comparison of Brazed Joint of Zircaloy-4 with PVD-Be and Zr-Be Amorphous alloys as Filler Metals (PVD-Be와 비정질 Zr-Be 합금을 용가재로 사용한 Zircaloy-4의 브레이징 접합부의 비교 연구)

  • Hwang, Yong-Hwa;Kim, Jae-Yong;Lee, Hyung-Kwon;Koh, Jin-Hyun;Oh, Se-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.2
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    • pp.113-119
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    • 2006
  • Brazing is an important manufacturing process in the fabrication of Heavy Water Reactor fuel rods, in which bearing and spacer pads are joined to Zircaloy-4 cladding tubes. The physical vapor deposition(PVD) technique is currently used to deposit metallic Be on the surfaces of pads as a filler metal. Amorphous Zr-Be binary alloys which are manufactured by rapid solidification process are under developing to substitute the conventional PVD-Be coating. In the present study, brazed joint with PVD and amorphous alloys of $Zr_{1-x}Be_{x}(0.3{\le}x{\le}0.5)$ as filler metals are compared by mechanism, microstructure and hardness. The thickness of brazed joint with amorphous alloys became much smaller than that of PVD-Be. The erosion of base metal did not occur in the brazed joint with amorphous alloys. The brazing mechanism for PVD-Be seems to be Be diffusion into Zr-4 with capillary action resulting from eutectic reaction while that for amorphous alloys are associated with the liquid phase formation in the brazed joint. The brazed joint microstructure with PVD-Be consists of dendrite while that with amorphous alloys is globular. The $Zr_{0.7}Be_{0.3}$ alloy shows the smooth interface with little erosion in the base metal and is recommended a most suitable brazing filler metal for Zircaloy-4.

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How to Improve the Ductility of Nanostructured Materials

  • Eckert J.;Duhamel C.;Das J.;Scudino S.;Zhang Z. F.;Kim, K. B.
    • Journal of Powder Materials
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    • v.13 no.5 s.58
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    • pp.340-350
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    • 2006
  • Nanostructured materials exhibit attractive mechanical properties that are often superior to the performance of their coarse-grained counterparts. However, one major drawback is their low ductility, which limits their potential applications. In this paper, different strategies to obtain both high strength and enhanced ductility in nanostructured materials are reported for Ti-base and Zr-base alloys. The first approach consists of designing an in-situ composite microstructure containing ductile bcc or hop dendrites that are homogeneously dispersed in a nanostructured matrix. The second approach is related to refining the eutectic structure of a Ti-Fe-Sn alloy. For all these materials, the microstructure, mechanical properties, deformation and fracture mechanisms will be discussed.

Cu-based Bulk Amorphous Alloys in the Cu-Zr-Ti-Ni-Pd System (Cu-Zr-Ti-Ni-Pd계 비정질 벌크합금의 형성과 성질)

  • Kim, Sung-Gyoo;Bae, Cha-Hurn
    • Journal of Korea Foundry Society
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    • v.22 no.6
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    • pp.304-308
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    • 2002
  • The new Cu-Zr-Ti-Ni-Pd amorphous alloy system has been introduced and manufactured using melt-spinning and Cu-mold die casting methods. Amorphous formability, the supercooled liquid region before crystallization and mechanical properties of the alloys were examined. The reduced glass transition temperature(Trg = Tg/Tm) and the supercooled liquid region(${\Delta}$Tx = Tx-Tg) of $Cu_{49}Zr_{30}Ti_{10}Ni_5Pb_6$ alloy were 0.620 and 57 K respectively. $Cu_{49}Zr_{30}Ti_{10}Ni_5Pb_6$ amorphous alloy was produced in the rod shape with 2mm diameter using the Cu-mold die casting. The hardness value of the amorphous bulk alloy was 432 DPN.

High Temperature Oxidation of Ti-15Mo-5Zr-3Al Alloy (Ti-15Mo-5Zr-3Al 합금의 고온산화)

  • 우지호;김종성;백종현;이동복
    • Journal of the Korean institute of surface engineering
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    • v.31 no.5
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    • pp.278-285
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    • 1998
  • Alloys of Ti-15Mo-5Zr-3Al(wt%) were oxidized in air between 700 and $900^{\circ}C$. It was found that the oxidation resistance is much better than that of either commercially available pure Ti-6Al-4V(wt%) alloys. The oxide scales were primarily composed of thick Ti-ox-ides which were formed by the inward diffusion of oxygen from the atmosphere. At higher temperatures a thin $\alpha$-$Al_2O_3$ layer was formed on Ti-oxides owing to the outward diffusion of Al from the base alloys. Molybdenum, the noblest metal among the alloy components, was predominantly present behind the oxide-substrate interface. Zirconium, an oxygen active metal, was present at both the oxide layer and the substrate.

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Localized Corrosion of Pure Zr and Zircaloy-4

  • Yu, Youngran;Chang, Hyunyoung;Kim, Youngsik
    • Corrosion Science and Technology
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    • v.2 no.6
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    • pp.253-259
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    • 2003
  • Zirconium based alloys have been extensively used as a cladding material for fuel rods in nuclear reactors, due to their low thermal neutron absorption cross-section, excellent corrosion resistance and good mechanical properties at high temperatures. However, a cladding material for fuel rods in nuclear reactors was contact water during long time at high-temperature, so it is necessary to improve the wear and corrosion resistance of the fuel cladding, At ambient environment, there are few data or paper on the characteristic of corrosion in chloride solution and acidic solution. The specimens used in this work are pure Zr and Zircaloy-4. Zircaloy-4 is a specific zirconium-based alloy containing, on a weight percent basis, 1.4% Sn, 0.2% Fe, 0.1% Cr. Pitting corrosion resistance of two alloys by ASTM G48 is higher than that of electrochemical method. Passive film formed on Zircaloy-4 is mainly composed of $ZrO_2$, metallic Sn, and iron species regardless of formation environments. Also, passive film formed on Zr alloys shows n-type semiconductic property on the base of Mott-Schottky plot.