• 한국주조공학회지
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• 제34권4호
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• pp.130-135
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• 2014

Efforts have been made to develop new silicon-free aluminum casting alloys that possess high electrical and thermal conductivity. In this research Al-Fe-Cu-Mg alloys with various Cu and Mg contents were investigated for their various properties. As the Cu or Mg content was increased, the electrical conductivity gradually decreased, while the tensile strength of the Al-Fe-Cu-Mg alloy tended to be improved. It was found that fluidity was generally inversely proportional to the Cu content, but the alloys containing 1%Mg showed considerably low fluidity, regardless of the Cu content.

• 한국주조공학회지
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• 제30권2호
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• pp.83-88
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• 2010

Bulk amorphous alloys with reasonable glass forming ability and large plasticity were found in Zr-Cu-Al alloys. Further increase in the GFA and the ductility is expected by appropriately choosing a fourth element. In this study, we select Be as the fourth element and added to the Zr-Cu-Al system to synthesize $(Zr_{57.4}Cu_{38.1}Al_{4.5})_{100-x}Be_x$(x=0~16) alloys and the glass forming ability and the plasticity were measured. With Be addition, the supercooled liquid region (${\Delta}T_x$), the plasticity and GFA as high as $134^{\circ}C$, 20.5%, 7 mm, respectively, can be obtained. Herein, we present the effect of Be addition on the variations of various mechanical properties and thermal characteristics of the $(Zr_{57.4}Cu_{38.1}Al_{4.5})_{100-x}Be_x$ alloys.

• 한국분말재료학회지
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• 제30권6호
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• pp.470-477
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• 2023

The effects of annealing on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Si alloys fabricated by high-energy ball milling (HEBM) and spark plasma sintering (SPS) were investigated. The HEBM-free sintered alloy primarily contained Mg₂Si, Q-AlCuMgSi, and Si phases. Meanwhile, the HEBM-sintered alloy contains Mg-free Si and θ-Al₂Cu phases due to the formation of MgO, which causes Mg depletion in the Al matrix. Annealing without and with HEBM at 500℃ causes partial dissolution and coarsening of the Q-AlCuMgSi and Mg₂Si phases in the alloy and dissolution of the θ-Al₂Cu phase in the alloy, respectively. In both alloys, a thermally stable α-AlFeSi phase was formed after long-term heat treatment. The grain size of the sintered alloys with and without HEBM increased from 0.5 to 1.0 ㎛ and from 2.9 to 6.3 ㎛, respectively. The hardness of the sintered alloy increases after annealing for 1 h but decreases significantly after 24 h of annealing. Extending the annealing time to 168 h improved the hardness of the alloy without HEBM but had little effect on the alloy with HEBM. The relationship between the microstructural factors and the hardness of the sintered and annealed alloys is discussed.

• 한국주조공학회지
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• 제41권5호
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• pp.419-433
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• 2021

Al-Si-Cu 합금은 구리 첨가에 따른 석출경화로 경도와 강도가 현저하게 강한 합금을 생성하는 장점이 있습니다. 그러나 구리를 첨가하면 Al-Si-Cu 합금의 응고 범위가 확장되고 합금은 응고 중에 발생하는 가장 흔하고 심각한 파단 현상 중 하나 열간 균열이 발생하기 쉽습니다. 합금의 열간 균열 특성에 대한 기존의 평가 방법은 이 특성에 대한 정량적 데이터를 제공하지 않는 상대적이고 정성적인 분석 방법입니다. 이 연구에서 Al-Si-Cu 주조 합금의 열간 균열 특성에 대한 더 신뢰할 수있는 정량 데이터를 얻기 위해 Instone et. al 이 개발 한 장치를 부분적으로 수정되었습니다. Cu 원소의 영향을 평가하기 위해 Al-Si-Cu 계 합금에서 4 가지 수준의 Cu 함량을 (0.5, 1.0, 3.0, 5.0) wt. %로 설정하고 각 합금에 대해 열간 균열 특성을 평가했습니다. Cu 함량이 증가함에 따라 열간 균열 강도는 (2.26, 1.53, 1.18, 1.04) MPa)로 감소했습니다. 열간 균열이 발생하는 시점, Cu 함량이 증가함에 따라 고액 공존 범위가 증가하여 동일 온도에서 해당 고상율 및 응고 속도가 감소하였다. 파단면의 형태는 수상 돌기에서 잔류 액상으로 덮인 수상 돌기로 바뀌었고, 열간 균열 발생 인근에서 CuAl₂ 상이 관찰되었다.

• 한국재료학회지
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• 제22권7호
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• pp.329-334
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• 2012

Two types of nanoclusters, termed Cluster (1) and Cluster (2) here, both play an important role in the age-hardening behavior in Al-Mg-Si alloys. Small amounts of additions of Cu and Ag affect the formation of nanoclusters. Two exothermic peaks were clearly detected in differential scanning calorimetry(DSC) curves by means of peak separation by the Gaussian method in the base, Cu-added, Ag-added and Cu-Ag-added Al-Mg-Si alloys. The formation of nanoclusters in the initial stage of natural aging was suppressed in the Ag-added and Cu-Ag-added alloys, while the formation of nanoclusters was enhanced at an aging time longer than 259.2 ks(3 days) of natural aging with the addition Cu and Ag. The formation of nanoclusters while aging at $100^{\circ}C$ was accelerated in the Cu-added, Ag-added and Cu-Ag-added alloys due to the attractive interaction between the Cu and Ag atoms and the Mg atoms. The influence of additions of Cu and Ag on the clustering behavior during low-temperature aging was well characterized based on the interaction energies among solute atoms and on vacancies derived from the first-principle calculation of the full-potential Korrinaga-Kohn-Rostoker(FPKKR)-Green function method. The effects of low Cu and Ag additions on the formation of nanoclusters were also discussed based on the age-hardening phenomena.

• 한국주조공학회지
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• 제20권2호
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• pp.89-96
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• 2000

The effects of modification processing on the refinement of primary Si and the wear behavior of hyper-eutectic Al-Si alloys have been mainly investigated. Refining effects of primary Si in Al-17%Si alloy was more efficient than that of B.390 alloy. Optimum condition of getting the finest primary Si microstructure was when AlCuP modifier is added into the melt at $750^{\circ}C$ and held it at $700^{\circ}C$ for 30 minutes. Wear loss in the specimens of as-cast condition decreases as the size of primary Si decreases, in the order of B.390 alloy, B.390 alloy with AlCuP addition, Al-17%Si alloy and Al-17%Si alloy with AlCuP addition. Wear loss in the aged condition of Al-17%Si alloy, B.390 alloy and B.390 alloy with AlCuP addition decreased due to the increase of compressive residual stress in the matrix by the aging treatment. While, wear loss increased in the aged specimens of Al-17%Si alloy with AlCuP addition and Hepworth addition in which compressive residual stress decreases by the aging treatment. Therefore, it is assumed that higher compressive residual stress in the matrix can reduce the wear loss in composite materials such as hyper-eutectic Al-Si alloys.

• 대한치과기공학회지
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• 제31권4호
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• pp.31-36
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• 2009

This study evaluated the grindability of series of Ti-Cu alloys in order to develop a Ti alloy with better grindability than commercially pure titanium(CP Ti). Experimental Ti-Xwt%Cu alloys(X=2, 5, 10) were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at circumferential speed(15000, 30000rpm) by applying a force(250, 300gr). Grindability was evaluated by measuring the amount of metal volume removed after grinding for 2 minutes. Data were compared to those for CP Ti and Ti-6wt%Al-4wt%V alloy. From results, It was observed that the grindability of Ti-Cu alloys increased with an increase in the Cu concentration compared to CP Ti, particularly the 10wt%Cu alloy exhibited the highest grindability at all speeds. By alloying with Cu, the Ti exhibited better grindability at high speed. The continuous precipitation of $Ti_2Cu$ among the ${\alpha}$-matrix grains made this material less ductile and facilitated more effective grinding because small segments more readily formed. The Ti-10wt%Cu alloy has a great potential for use as a dental machining alloy.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 추계학술발표 개요집
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• pp.169-172
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• 1994

• The Journal of Advanced Prosthodontics
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• 제6권3호
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• pp.215-223
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• 2014

PURPOSE. This study aimed to develop a copper-aluminium-nickel alloy which has properties comparable to that of dental alloys used for dental post and core applications with the reasonable cost. MATERIALS AND METHODS. Sixteen groups of experimental copper alloys with variants of 3, 6, 9, 12 wt% Al and 0, 2, 4, 6 wt% Ni were prepared and casted. Their properties were tested and evaluated. The data of thermal, physical, and mechanical properties were analyzed using the two-way ANOVA and Tukey's test (${\alpha}$=0.05). The alloy toxicity was evaluated according to the ISO standard. RESULTS. The solidus and liquidus points of experimental alloys ranged from $1023^{\circ}C$ to $1113^{\circ}C$ and increased as the nickel content increased. The highest ultimate tensile strength ($595.9{\pm}14.2$ MPa) was shown in the Cu-12Al-4Ni alloy. The tensile strength was increased as the both elements increased. Alloys with 3-6 wt% Al exhibited a small amount of 0.2% proof strength. Accordingly, the Cu-9Al-2Ni and Cu-9Al-4Ni alloys not only demonstrated an appropriate modulus of elasticity ($113.9{\pm}8.0$ and $122.8{\pm}11.3$ GPa, respectively), but also had a value of 0.2% proof strength ($190.8{\pm}4.8$ and $198.2{\pm}3.4$ MPa, respectively), which complied with the ISO standard requirement (>180 MPa). Alloys with the highest contents of nickel (6 wt% Ni) revealed a widespread decolourisation zone (5.0-5.9 mm), which correspondingly produced the largest cell response, equating positive control. CONCLUSION. The copper alloys fused with 9 wt% Al and 2-4 wt% Ni can be considered for a potential use as dental post and core applications.

• Journal of Welding and Joining
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• 제10권4호
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• pp.213-221
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• 1992

Al$_{2}$O$_{3}$ ceramic coating layer by gas flame spraying was very porous, therefore it could not have wear and corrosion resistance at all. To get a dense and strong coating layer, a method to infiltrate an alloy into the pores of $Al_{2}$O$_{3}$ ceramic coating was investigated. Cu-Ti alloys, which had good wettability and reactivity with $Al_{2}$O$_{3}$ ceramic, were examined for infiltration. Infiltration of the alloys was performed in vacuum at 1100.deg.C. The melt of Cu-50 at % Ti alloy was well penetrated through the porous $Al_{2}$O$_{3}$ coating and tightly sealed the pores, unbounded area and microcracks in the coating. The alloy melt in the pores reacted with $Al_{2}$O$_{3}$ ceramic to produce a suboxide phase, Cu$_{2}$Ti$_{4}$O. This composite layer which was composed of $Al_{2}$O$_{3}$ and Cu$_{2}$Ti$_{4}$O phase had good microstructure and wear and corrosion resistance. Additionally, microstructures at interfaces between coating layers were greatly improved owing to the effect of vacuum heat treating.