• Title/Summary/Keyword: Cu alloys

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A Study on the Solidification Structure in the Al-Cr Alloys (Al-Cr계 합금의 응고 조직에 관한 연구)

  • 배석천;조순형
    • Journal of Welding and Joining
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    • v.13 no.3
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    • pp.46-54
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    • 1995
  • The structural changes of Al-Cr alloys due to the difference in the growth rates were investigated in the study using the water cooled copper chill apparatus, the levitation apparatus, and the melt spinner. Growth rate was evaluated by means of thermal analysis could measured the cooling rate up to 10$^{5}$ K/sec. The transformation from the cell structure to the massive transformed structure was obtained the Al-3.43wt%Cr alloy in the melt spinner method.

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Formation and Properties of Mg-Cu-(Si, Ge) Amorphous Alloys

  • Kim, Sung-Gyoo;Park, Heung-Il
    • Journal of Korea Foundry Society
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    • v.17 no.5
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    • pp.458-464
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    • 1997
  • Mg-Cu-Si과 Mg-Cu-Ge계 3원 합금에서 비정질 생성범위와 열적, 기계적 성질을 조사하였다. Mg-Cu-Si계에서는 $15{\sim}45%Cu$, $0{\sim}10%Si$, Mg-Cu-Ge계에서는 $15{\sim}45%Cu$, $0{\sim}5%Ge$의 조성범위에서 각각 비정질 단상이 생성되었고, $15{\sim}22.5%Cu$, 2.5%Si(or Ge)의 조성범위에서 생성되는 비정질상은 180도 밀착굽힘을 하여도 파단되지 않는 양호한 인성을 가지고 있었으며, $Mg_{82.5}Cu_{15}Ge_{2.5}$비정질합금의 최대인장강도는 800 MPa로 결정질 Mg기 합금의 최대치인 300 MPa에 비해 월등히 높은 값을 나타내었다. 그러고 비정질합금의 결정화는 다음과 같은 과정으로 일어났다. 1) Si(or Ge) ${\le}$ 2.5%: 비정질 ${\to}$ 비정질+$Mg_2Cu$+Mg ${\to}$ $Mg_2Cu$+Mg+$Mg_2Si$(or Ge), 2) Si(or Ge)=5%: 비정질 ${\to}$ $Mg_2Cu$+Mg+$Mg_2Si$(or Ge), 3) Si=10%: 비정질 ${\to}$ 비정질+$Mg_2Si$ ${\to}$ $Mg_2Si$+$Mg_2Cu$+Mg.

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Surface segregation of NiZr and CuZr alloys.

  • Kang, H.J.;Park, N.S.;Kim, M.W.;O'Conner, D.J.;Macdonald, R.J.
    • Proceedings of the Korean Vacuum Society Conference
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    • 1994.02a
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    • pp.35-35
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    • 1994
  • The surface segragation of NiZr, CuZr alloy has been studied wi th X-ray Imotoelectron spectroscopy(XPS), Auger electron spectroscopy(AES) and low energy ion scattering(LEIS). The composition of outmost atomic layer has been determinded by the use of LEIS at several incident energies using Ar+ ion. In the LEIS analysis, the effect of charge exchange has been estimated by a novel measurment of the charge exchange parameters while simul taneous determining the relative concentrations of Ni and Zr and the complementary information obtained will be described. The composition of the clean annealed surface, measured with AES only, will be contrasted wi th the surface concentration of the preferentially sputtered surface. The experimental results has been clearly demonstrated that when the NiZr ruld CuZr alloys are exposed to continuous Ar+ ion bombardment the outermost atomic layer is Zr rich due to preferential sputtering of Ni atoms. where Ni is preferentially sputtered, but the difference in sputtering yields is not sufficient to explain the observed composition. Therefore, it is necessary to consider other processes such as Radiation Induced Segregation(RIS). The surface composition of the heated sample surface predicts that Zr should surface segregate which futher supports the view that part of the Zr enrichment is due to RIS.to RIS.

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Microstructural Characterization of Hot Extruded Al-Zn-Mg-Cu Alloys Containing Sc (Sc을 첨가한 Al-Zn-Mg-Cu 합금 압출재의 열처리에 따른 미세구조 변화)

  • 이혜경;서동우;이상용;이경환;임수근
    • Transactions of Materials Processing
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    • v.13 no.1
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    • pp.53-58
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    • 2004
  • The microstructural changes of Al-Zn-Mg-Cu alloy containing Sc during hot extrusion and post heat treatment were investigated. Two kinds of Al-Sc alloys with different alloying elements (B1, B2) were hot extruded to make T-shape bars at extrusion temperature of $380^{\circ}C$, then the bars were solution treated at $480^{\circ}C$ for 2hrs followed by artificial aging at $120^{\circ}C$ for 24hrs. The interior microstructure of as extruded bar consisted of elongated grains, however, fine equiaxed grains were also observed around surface. The microstructural gradient suggested that different restoration process could proceed during the hot extrusion. For B1 and B2, different grain growth behaviors were found around the surface during the post heat treatment. Rapid grain growth behavior was observed for B1 around the surface, however, it was not observed for B2. Orientation pinning, which was related with the evolution of preferred orientation, and precipitation were thought to be responsible for the rapid grain growth.

A Study on the Formation of Functionally Composite Layer on Al Alloy Surface by Plasma Transferred Arc Overlaying Process (Plasma Transferred Arc 오버레이법에 의한 Al 합금 표면층의 복합기능화에 관한 연구)

  • 임병수;황선효;서창제
    • Journal of Welding and Joining
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    • v.17 no.5
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    • pp.107-115
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    • 1999
  • The objective of this research was to study the formation of the thick hardened layer with the addition of metal powder(Cu) and ceramics powders(TiC) on the aluminum 5083 alloys by plasma transferred arc process(PTA process) and to characterize the effect of overlaying conditions on the overlaid layer formation. This was followed by investigating the microstructures of the overlaid layers and mechanical properties such as hardness and wear resistance. The overlaid layer containing copper powder was alloyed and intermetallic compound($CuAl_2$) was formed. The overlaid layers with high melting point TiC powders, however, did not react with base metal. Wear resistance of the alloyed layer was remarkably improved by the formation of $CuAl_2$, precipitate phase, which prevented wear of base aluminum alloys and at higher wear speed, accelerated sliding of the counter part. Wear resistance of the composite layer was also remarkably improved because TiC powder act as a load barring element and Fe debris fragments detached from the counter part act as a solid lubricant on the contact surface.

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Effect of Ca and Al Additions on the Magnetic Properties of Nanocrytalline Fe-Si-B-Nb-Cu Alloy Powder Cores

  • Moon, Sun Gyu;Kim, Ji Seung;Sohn, Keun Yong;Park, Won-Wook
    • Journal of Magnetics
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    • v.21 no.2
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    • pp.192-196
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    • 2016
  • The Fe-Si-B-Nb-Cu alloys containing Ca and Al were rapidly solidified to thin ribbons by melt-spinning. The ribbons were ball-milled to make powders, and then mixed with 1 wt.% water glass and 1.5 wt.% lubricant. The mixed powders were burn-off, and then compacted to form toroidal-shaped cores, which were heat treated to crystallize the nano-grain structure and to remove residual stress of material. The characteristics of the powder cores were analyzed using a differential scanning calorimetry (DSC) and a B-H meter. The microstructures were observed using transmission electron microscope (TEM). The optimized soft magnetic properties (${\mu}_i$ and $P_{cv}$) of the powder cores were obtained from the Ca and Al containing alloys after annealing at $530^{\circ}C$ for 1 h. The core loss of Fe-Si-B-Nb-Cu-based powder cores was reduced by the addition of Ca element, and the initial permeability increased due to the addition of Al element.

Evaluation of Hot Tear Susceptibility of Al-Si-Mg-Cu Alloy System (Al-Si-Mg-Cu 합금계의 열간 균열 특성 평가방법에 관한 연구)

  • Son, Kwang-Suk;Park, Tae-Eun;Kim, Jin-Su;Kang, Sung-Min;Kim, Donggyu
    • Korean Journal of Metals and Materials
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    • v.48 no.5
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    • pp.436-444
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    • 2010
  • The hot tear susceptibility of Al alloys was investigated by using a constrained-rod mold designed to quantify 8 types of tear tendency. The severity of the crack was scored by 5 grades on a scale of 0 to 4, with 0 being "no crack formed" and 4 being "complete separation by crack". The Hot Tear Susceptibility index (HTS) which consists of crack type scores and position scores, was proposed to compare the hot tear tendency of Al alloys. A356.0 cast alloy and AA6061 wrought Al alloy showed an HTS value of 27.5 and 53 respectively. The effects of Si, Cu, and Mg content on hot tear tendency were also investigated with a constrained-rod mold. The variation of HTS values with alloying elements represents similar behavior in the variation of the solidification range in a pseudo binary phase diagram.

Improvement of R-value in Al-Mg-Si-Cu Alloy Sheets by Cross Rolling (크로스 압연에 의한 Al-Mg-Si-Cu 합금 판재의 소성변형비의 향상)

  • Lee, Kwang-jin;Jeon, Jae-yeol;Woo, Kee-do
    • Korean Journal of Metals and Materials
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    • v.49 no.6
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    • pp.488-492
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    • 2011
  • Heat-treatable Al-Mg-Si-Cu alloy sheets, which are expected to have a growing demand, were fabricated by Cross rolling to improve their formability. The mechanical properties and texture of the sheets after the final annealing process were investigated by a tensile test, EBSD and XRD analysis. The grain size of the cross-rolled sheets was remarkably decreased compared to conventional rolled sheets, and the R-value of the cross-rolled sheets was notably increased by about one and a half times that of the conventional rolled sheet. Cube{001}<100> and cubic system orientations were strongly developed in conventional rolled sheets. However, randomized textures were formed in the cross-rolled sheets without specific texture. It is thought that much shear deformation was induced during the cross rolling. The results show that the cross rolling method is effective for improving the R-value of aluminum alloys sheets and their grain refinement. As a result, it is considered that cross rolling is effective for improving formability.

Densification of Cu-50%Cr Powder Compacts and Properties of the Sintered Compacts (Cu-50%Cr 분말성형체의 치밀화 및 소결체 물성)

  • 김미진;정재필;도정만;박종구;홍경태
    • Journal of Powder Materials
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    • v.7 no.4
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    • pp.218-227
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    • 2000
  • It is well known that the Cu-Cr alloys are very difficult to be made by conventional sintering methods. This difficulty originates both from limited solubility of Cr in the Cu matrix and from limited sintering temperature due to high vapor pressures of Cr and Cu components at the high temperature. Densification of Cu-50%Cr Powder compacts by conventional Powder metallurgy Process has been studied. Three kinds of sintering methods were tested in order to obtain high-density sintered compacts. Completely densified Cu-Cr compacts could be obtained neither by solid state sintering method nor by liquid phase sintering method. Both low degree of shrinkage and evolution of large pores in the Cu matrix during the solid state sintering are attributed to the anchoring effect of large Cr particles, which inhibits homogeneous densification of Cu matrix and induces pore generation in the Cu matrix. In addition, the effect of undiffusible gas coming from the reduction of Cu-oxide and Cr-oxide was observed during liquid phase sintering. A two-step sintering method, solid state sintering followed by liquid phase sintering, was proved to have beneficial effect on the fabrication of high-dendsity Cu-Cr sintered compacts. The sintered compacts have properties similar to those of commercial products.

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