• Title/Summary/Keyword: Cu-alloy

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A New Cu-Hf-Al-Be Bulk Amorphous Alloy with High Glass Forming Ability (우수한 비정질 형성능을 가지는 Cu-Hf-Al-Be 4원계 벌크 비정질 합금)

  • Shin, Sang-Soo;Lim, Kyoung-Mook;Kim, Seong-Nyeong;Kim, Eok-Soo
    • Journal of Korea Foundry Society
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    • v.31 no.4
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    • pp.186-190
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    • 2011
  • A new Cu-Hf-Al-Be monolithic bulk amorphous alloy was developed utilizing minimal use of toxic and expensive Be. The developed alloy exhibits a large glass forming ability (GFA) (${\Phi}8$ mm). The possible mechanisms underlying the enhancement of the glass forming ability by this alloy are discussed based on the dimensionless parameter ${\gamma}$. In addition, alloy design strategy for the improvement of GFA is proposed in the viewpoint of heat of mixing (${\Delta}H_{mix}$)difference and atomic packing state.

A surface chemical analysis strategy for the microstructural changes in a CuAgZrCr alloy cast under oxidation conditions

  • Ernesto G. Maffia;Mercedes Munoz;Pablo A. Fetsis;Carmen I. Cabello;Delia Gazzoli;Aldo A. Rubert
    • Advances in materials Research
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    • v.13 no.2
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    • pp.141-151
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    • 2024
  • The aim of this work was to determine the behavior of alloy elements and compounds formed during solidification in the manufacturing process of the CuAgZrCr alloy under an oxidizing environment. Bulk and surface analysis techniques, such as Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Raman and X-ray diffraction (XRD) were used to characterize the phases obtained in the solidification process. In order to focus the analysis on the on grain boundary interface, partial removal of the matrix phase by acid attack was performed. The compositional differences obtained by SEM-EDX, Raman and XPS on post-manufacturing materials allowed us to conclude that the composition of grain boundaries of the alloy is directly influenced by the oxidizing environment of alloy manufacturing.

Grain Refining and Age Hardening of Mg-Zn Alloys by Addition of Cu and Si (Cu 및 Si첨가에 의한 Mg-Zn합금계의 입자미세화 및 시효경화)

  • Hwang, Jin-Hwan;Nam, Tae-Hyeon;An, In-Seop;Kim, Yu-Gyeong;Heo, Gyeong-Cheol;Heo, Bo-Yeong
    • Korean Journal of Materials Research
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    • v.5 no.6
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    • pp.682-689
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    • 1995
  • In order to refine the grain size of Mg-Zn alloy 0.5 to 6wt.%Cu or Si elements were added. Alloy ingot was made under vacuum atmosphere of 4 ${\times}$ 10$\^$-4/ Torr in the quartz tube coated by BN. Grain size and hardness were measured after solution treatment for 8 hours at 435$^{\circ}C$. Optimal condition for grain size refining effect was obtained at the minimum composition of 2wt.%Cu or 1.5wt.%Si addition to Mg-6wt%Zn alloy. Age hardening behavior was experimented at the optimal compositions of the Mg-6wt.%Zn, Mg-6wt.% Zn-2wt.%Cu and Mg-6wt.% Zn-1.5wt.%Si. The hardness increment due to fine grain size was higher at the Mg-Zn-Cu alloy system, but that due to age hardening was higher at the Mg-Zn-Si alloy system.

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Effect of Cu content on Hot Tearing Susceptibility in Al-Si-Cu Aluminum Casting Alloy (Al-Si-Cu 알루미늄 주조 합금의 열간 균열 민감성에 미치는 Cu 함량의 영향)

  • Oh, Seung-Hwan;Munkhdelger, Chinbat;Kim, Heon-Joo
    • Journal of Korea Foundry Society
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    • v.41 no.5
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    • pp.419-433
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    • 2021
  • Al-Si-Cu alloys benefit from the addition of copper for better hardness and strength through precipitation hardening, which results in remarkably strong alloys. However, the addition of copper expands the solidification range of Al-Si-Cu alloys, and due to this, these alloys become more prone to hot tearing, which is one of the most common and serious fracture phenomena encountered during solidification. The conventional evaluation method of the hot tearing properties of an alloy is a relative and qualitative analysis approach that does not provide quantitative data about this phenomenon. In the present study, the mold itself part of a device developed in Instone et al. was partially modified to obtain more reliable quantitative data pertaining to the hot tearing properties of an Al-Si-Cu casting alloy. To assess the influence of Cu element, four levels of Cu contents were tested (0.5, 1.0, 3.0, and 5.0 wt.%) in the Al-Si-Cu system alloy and the hot tearing properties were evaluated in each case. As the Cu content was increased, the hot tearing strength decreased to 2.26, 1.53, 1.18, and 1.04 MPa, respectively. At the moment hot tearing occurred, the corresponding solid fraction and solidification rate decreased at the same temperature due to the increase in the solid-liquid coexistence range as the Cu content increased. The morphology of the fracture surfaces was changed from dendrites to dendrites covered with residual liquid, and CuAl2 phases were observed in the vicinity of hot tearing.

Microstructure and Mechanical Properties on Solid Solution Heat Treatment of Al-6Si-2Cu Alloy for Lightweight Automotive (자동차용 Al-6Si-2Cu 합금의 용체화처리에 따른 미세조직 및 기계적 특성 변화)

  • Hong, Seung-Pyo;Kim, Chung-Seok
    • Korean Journal of Materials Research
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    • v.24 no.10
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    • pp.538-542
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    • 2014
  • Microstructural and mechanical characteristics of Al-6Si-2Cu alloy for lightweight automotive parts were investigated. The test specimens were prepared by gravity casting process. Solution heat treatments were applied to as-cast alloys to improve mechanical properties. The microstructure of the gravity casting specimen presents a typical dendrite structure, having a secondary dendrite arm spacing (SDAS) of $37{\mu}m$. In addition to the Al matrix, a large amount of coarsened eutectic Si, $Al_2Cu$ intermetallic phase, and Fe-rich phases were identified. After solution heat treatment, single-step solution heat treatments were found to considerably improve the spheroidization of the eutectic Si phase. Two-step solution treatments gave rise to a much improved spheroidization. The mechanical properties of the two-step solution heat treated alloy have been shown to lead to higher values of properties such as tensile strength and microhardness. Consequentially, the microstructural and mechanical characteristics of Al alloy have been successfully characterized and are available for use with other basic data for the development of lightweight automotive parts.

Variation of Lattice Constant in Ni-W and Ni-W-Cu Alloys for YBCO Coated Conductor (YBCO 초전도 박막 선재용 Ni-W 및 Ni-W-Cu 합금의 격자상수 변화)

  • Kim Min-Woo;Jung Kyu-Dong;Jun Byung-Hyuk;Kim Hyoung-Seop;Kim Chan-Joong
    • Progress in Superconductivity
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    • v.7 no.1
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    • pp.64-68
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    • 2005
  • We fabricated Ni-based alloy substrates for YBCO coated conductor using powder metallurgy. Tungsten and copper were selected as alloy elements due to their mutual solubility to the base element of nickel. The alloying elements were mixed with nickel using ball milling and dried in air. The powder mixtures were packed in a rubber mold, cold isostatic pressed 200 MPa and made into rods. The compacted rods were sintered at $1150^{\circ}C$ for 6 hours for densification. It was confirmed by neutron diffraction experiment that W and Cu atoms made complete solid solution with Ni. Lattice constant of nickel alloy increased by $0.004{\AA}$ for 1at. $\%$ W in Ni-W alloy, $0.0006{\AA}$ for 1 at. $\%$ Cu in Ni-W-Cu alloy.

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A Nanoindentation Based Study of Mechanical Properties of Al-Si-Cu-Mg Alloy Foam Cell Wall (나노인덴테이션에 의한 Al-Si-Cu-Mg 합금 폼 셀 벽의 기계적 물성 연구)

  • Ha, San;Kim, Am-Kee;Lee, Chang-Hun;Lee, Hak-Joo;Ko, Soon-Gyu;Cho, Seong-Seock
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.382-387
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    • 2004
  • Nanoindentation technique has been used to measure the mechanical properties of aluminium alloy foam cell walls. Al-Si-Cu-Mg alloy foams of different compositions and different cell morphologies were produced using powder metallurgical method. Cell morphology of the foam was controlled during production by varying foaming time and temperature. Mechanical properties such as hardness and Young's modulus were calculated using two different methods: a continuous stiffness measurement (CSM) and an unloading stiffness measurement (USM) method. Experimental results showed that hardness and Young's modulus of Al-5%(wt.)Si-4%Cu-4%Mg (544 alloy) precursor and foam walls are higher than those of Al-3%Si-2%Cu-2%Mg (322 alloy) precursor and foam walls. It was noticed that mechanical properties of cell wall are different from those of precursor materials.

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The Optimal Solution Treatment Condition in a Al-Si-Cu AC2B Alloy (Al-Si-Cu계 AC2B 합금의 최적 용체화 처리 조건)

  • Jung, Jae-Gil;Park, June-Soo;Ha, Yang-Soo;Lee, Young-Kook;Jun, Joong-Hwan;Kang, Hee-Sam;Lim, Jong-Dae
    • Korean Journal of Metals and Materials
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    • v.47 no.4
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    • pp.223-227
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    • 2009
  • The precipitates, hardness, and tensile properties of Al-6.2Si-2.9Cu AC2B alloy were investigated with respect to solution treatment time at $500^{\circ}C$. $Al(Cu)-Al_2Cu$ eutectic, Si, ${\theta}-(Al_2Cu)$, and $Q-(Al_5Cu_2Mg_8Si_6)$ phases were observed in the as-cast specimen. With increasing the solution treatment time at $500^{\circ}C$, the $Al(Cu)-Al_2Cu$ eutectic and ${\theta}-(Al_2Cu)$ phases were gradually reduced and finally almost disappeared in 5 h. The mechanical properties, such as hardness, tensile strength, and elongation, were improved with solution treatment time until about 5 h due to the dissolution of the $Al_2Cu$ particles. With further holding time, the mechanical properties did not change much. The solution treated specimens for over 5 h at $500^{\circ}C$ exhibit almost the same tensile properties even after aging at $250^{\circ}C$ for 3.5 h. Accordingly, the optimal solution treatment condition of the Al-Si-Cu AC2B alloy is considered to be 5 h at $500^{\circ}C$.

A New TEM Observation of the Copper Precipitate in High Strength Al-Cu-Mg Alloy (고강도 알루미늄 합금(Al-Cu-Mg)에서 새로운 Cu 석출물의 TEM 관찰)

  • Kim, Hwang-Su
    • Applied Microscopy
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    • v.36 no.2
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    • pp.47-55
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    • 2006
  • In this paper a transmission electron microscope (TEM) observation of fine Cu precipitates distributed randomly in Al-2.5Cu-1.5Mg wt.% alloy is first reported. This new observation happened to occur when an ion milling was peformed to remove oxides on the specimen, particularly, aged 100 hours at $150^{\circ}C$. Meanwhile the oxides were identified to be $Cu_2O$ particles. For this work involved with analysis of diffraction rings, the formulation of the electron diffraction rings pattern for powder particles was made. Finally the significance of this unexpected ion milling effort on the alloy was discussed

A Study on the Thermal and Electrical Properties of Fabricated Mo-Cu Alloy by Spark Plasma Sintering Method (방전 플라즈마 소결법으로 제작한 Mo-Cu 합금의 열적, 전기적 특성)

  • Lee, Han-Chan;Lee, Boong-Joo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.11
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    • pp.1600-1604
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    • 2017
  • Mo-Cu alloys have been widely used for heat sink materials, vacuum technology, automobile and many other applications due to their excellent physical and electronic properties. Especially, Mo-Cu composites with 5~20 wt% copper are widely used for the heavy duty service contacts due to their excellent properties like low coefficient of thermal expansion, wear resistance, high temperature strength and prominent electrical and thermal conductivity. In most of the applications, high dense Mo-Cu materials with homogeneous microstructure are required for high performance, which has led in turn to attempts to prepare ultra-fine and well-dispersed Mo-Cu powders in different ways, such as spray drying and reduction process, electroless plating technique, mechanical alloying process and gelatification-reduction process. However, most of these methods were accomplished at high temperature (typically degree), resulting in undesirable growth of large Cu phases; furthermore, these methods usually require complicated experimental facilities and procedure. In this study, Mo-Cu alloying were prepared by planetary ball milling (PBM) and spark plasma sintering (SPS) and the effect of Cu with contents of 5~20 wt% on the microstructure and properties of Mo-Cu alloy has been investigated.