Papers by Keyword: Copper Alloy

Abstract: The semi-solid extruded ZCuSn10P1 copper alloy were annealed at different temperatures and time. The influences of heat treatment temperature and holding time on the microstructure of semi-solid ZCuSn10P1 copper alloy were investigated. The results show that with the increase of heat treatment temperature, the morphology of the semi-solid microstructure was improved, the sharp angle around the primary phase α-Cu and the liquid droplets were reduced. With the increase of heat treatment time, the solid-liquid segregation of the semi-solid structure was improved. The average grain size of the solid phase increased with the increasing of the holding time. After heat treatment, the solid solubility of the primary phase α-Cu increased, and the Sn and P elements in the liquid phase continued to diffuse to the primary phase α-Cu. The microstructure of semi-solid copper alloy was the most uniform after heat treatment at 350°C for 120 min.

Abstract: Additive manufacturing (AM) is a prominent technology in the industrial fields such as aerospace, medical, automotive and so on. Especially, selective laser melting (SLM) process is available to create three-dimensional complicated structures of various alloys such as stainless steel, titanium alloy, aluminium alloy, nickel-based superalloy and so on. And also, copper and copper alloys are used as a material for products with complicated shape, electrical components, and a heat exchanger because of having the high electrical conductivity and the high thermal conductivity. It is known that copper alloys show a good shape memory behaviour by adding Al, Ni and Zn. Especially, Cu-Al-Ni alloy shows a good shape memory properties at high temperature. However, it is difficult to fabricate high-density Cu-Al-Ni alloy by the SLM process. This is mainly because Cu-Al-Ni alloy has high elastic anisotropy and brittleness in polycrystalline state. In this research, the optimum fabrication condition of Cu-Al-Ni alloy by SLM process was investigated. The optimum laser power and scan speed were able to be found by evaluating the surface morphology, density and microstructure of the as-build specimens.The maximum density of the as-built specimen was 99.47%.

Abstract: The microstructure evolution and mechanical properties of a copper alloy subjected to deformation at temperatures of 20 °C and 400 °C to total strains from 1 to 4 were examined. The formation of planar low-angle boundaries with moderate misorientations occurs within initial grains at relatively small strains regardless of deformation temperature. Upon further processing the misorientations of these boundaries progressively increase and the new ultrafine grains develop. Continuous dynamic recrystallization takes place during deformation at ambient and elevated temperatures. The kinetics of dynamic recrystallization is discussed in terms of a modified Johnson-Mehl-Avrami-Kolmogorov relationship. The large plastic straining results in significant strengthening, the ultimate tensile strength increases from 190 MPa in the initial state to 440 MPa and to 400 MPa after total strain of 4 at 20 °C and 400 °C, respectively. A modified Hall-Petch relationship is applied to evaluate the contribution of grain refinement and dislocation density to the overall strengthening.

Abstract: National Institute for Fusion Science (NIFS) launched in 2014 a research program for developing Dispersion Strengthened (DS) Cu alloys for application to the heat sink materials of divertors of fusion reactors, using newly installed ball-milling, encapsulation, and Hot Isostatic Pressing (HIP) facilities. A unique feature of these facilities is that the entire process can be performed without exposing the materials to air, enabling precise impurity control. Cu-Al, Cu-Zr and Cu-Y alloys have been produced in this program. Various technological advancement has been made for the fabrication, such as suppression of powder adhesion to the wall of containers during the ball milling, and encapsulation technology including development of small volume tubular capsules.

Abstract: Nowadays virtual prototyping has a great impact in the design process of an industrial component. Numerical techniques based on the Finite Element Method (FEM) are mature to provide computational tools that permit complex phenomena to be accurately simulated, even when dealing with multi-physical problems. This work puts in evidence that an inaccurate assessment of the material properties may compromise the benefit of such complex modelling techniques. For this purpose, firstly the case of thermo-mechanically loaded structures will be presented. Considering fire walls for naval applications, the influence of the rock wool elastic modulus in the safety behavior will be emphasized. In the case of steel making component, the paper proofs that only a correct cyclic plasticity model of the material (copper alloy) permits a durability analysis to be accurately performed. Finally, in the case of an energy-harvesting device, the importance of taking into account the orthotropic properties of the material will be highlighted.

Abstract: Copper molds are adopted in continuous casting to provide an initial solidification of steel. The presence of molten steel induces relevant temperature gradients across mold walls. This, in turn, generates high stress levels, exceeding the yielding limit of the material. Recent works confirm that thermal distortion occurs due to both creep and cyclic plasticity. In this work a numerical investigation is developed, simulating the mold behavior under repeated heating and cooling sequences. The aim of this work is to compare the performances in terms of permanent distortion of different copper alloys usually adopted for such application. It can be observed that both material properties and operating temperature have a significant influence in the permanent distortion evolution.

Abstract: The process of continuous extrusion Conform, relating to modern energy-efficient metalworking technologies, is now widespread in the production of hollow and solid long-cut profiles of various cross-sections made of aluminum and copper alloys. However, in questions relating to the metal flow pattern and the formation of microstructure and mechanical properties, directly at the deformation zone, it has not studied sufficiently [1]. The work aimed at studying the nature of the metal flow and the transformation of the microstructure and mechanical properties of the copper alloy GOST-M1 (DIN-ECu-57) in the deformation zone during the pressing of round (Ø 8, 24, 30 mm) and flat (10 × 30, 10 × 60, 10 × 80, 10 × 100 mm) profiles. It was performed on the basis of New Metallurgical Technologies Ltd. and the department of metal forming of the NUST MISiS. In the pressing process, the templates of these profiles were selected, further samples for experiment were made and the study of the nature of the alloy flow in the longitudinal direction were carried out (continuous casting - deformation center - finished profile).

Abstract: Thin-walled pipes made of copper alloys – the brass grades L96, L68, L63, LANKMc; the bronze grade BrOF (the GOST state standard) are of great demand in aircraft, shipbuilding, automotive, defense, diesel and instrument-making industries. Pipe diameter ranges between 4.0 and 20 mm, and wall thickness is in the range from 0.1 to 0.6 mm. The manufacture of these pipes using traditional technological schemes is characterized by high labor input and low stability in providing quality characteristics, such as dimensional accuracy, the presence of surface defects and the level of mechanical properties. This study presents scientific evidence, new technological schemes developed for manufacturing pipes made of copper alloys with the use of the equipment and technology of multiple drawing on a long movable mandrel and results of their adoption at Revda Non-Ferrous Metal Processing Works JSC.

Abstract: Gas atomization is one of the most cost-effective methods for preparing spherical powders. The Cu-9.7Sn-0.2P alloy powder for 3D printing was prepared by a self-developed double nozzle gas atomization technique with different deliver tube diameters, and the particle size and shape of the powder were characterized. Results show that the powder particles are mostly nearly spherical, mixed with a few irregular powders. The average O. Bluntness of the powders are 60~70%, the average Outgrowths are lower than 18%. The deliver tube diameter affects the powder characteristics directly. The increase of the diameter increases the particle size of the powder and reduces the sphericity. At the same time, the adhesion of the satellite powder decreases, the flowability becomes better and the oxygen content drop. The surface and internal structure of the powder are mainly cellular and dendritic structures.

Abstract: A comparative study on the friction and wear properties of three kinds of copper alloys, including Cu-Ni based, Cu-Al and Cu-Be alloys was carried out in this study. The friction pair was stainless steel, and both dry and MoS₂ lubrication friction experiments were investigated. During the experiments, different loads were chosen for different alloys. It was found that under dry friction condition, the friction coefficients of both Cu-Ni based and Cu-Al alloys did not change as the loads changes, whereas the friction coefficient of Cu-Be alloy increased as the loads increases. Under lubrication friction condition, the friction coefficients of all three alloys did not change as the load changes. The results show that the dry friction coefficient of Cu-Ni based alloy was the largest (0.74), the Cu-Al alloy next (0.60), and the Cu-Be alloy had the smallest dry friction coefficient (0.54). The lubrication friction coefficient of Cu-Ni based and Cu-Be was equal and relatively smaller (0.12), whereas the Cu-Al alloy had a relative larger lubrication friction coefficient (0.27). The microstructure observations were consistent with the friction and wear performance, and the SEM results show that different wear mechanisms were dominated for different alloys.