High Strength Copper Research Articles

AUSTRAL WRIGHT ALLOY B25 (UNS C17200)

Abstract Austral Wright Alloy B25 (UNS C17200) is a wrought beryllium copper alloy. It provides the highest strength of any copper alloy, with electrical conductivity considerably greater than that of other high-strength copper alloys. Since it is heat treated after forming, it provides excellent formability and ductility. This alloy features good stress relaxation resistance and high fatigue strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Cu-943. Producer or source: Austral Wright Metals.

High-strength copper foil prepared with 2-mercaptothiazoline by direct current electrodeposition

A kind of new additive for ultra-thin copper foils with high tensile strength is reported in this work. The highest strength is about 700 MPa with 12 mg/L 2-mercaptothiazoline, and the strengthening effects and mechanisms in different concentrations are studied in detail. 2-Mercaptothiazoline significantly improves the tensile strength of electrolytic copper foils by refining the grains and effectively impeding the slips of dislocations. Fine grains also provide a smooth and flat surface for foils, and weaken the preferred orientation of grains in the cross-section, contributing to the high strength of copper foils at different aspects. The addition of the 2-mercaptothiazoline obviously inhibits the electron transfer process of metal electrodeposition and enhances the electrochemical polarization, resulting in high nucleation density and small nuclei to form fine grains. The high-strength copper foils with a very thin thickness are placed great expectations on the industrial application of lithium-ion batteries.

Influence of processing innovations on joint strength improvements in friction stir welded high strength copper alloys

One of the major challenges in welding the Cu–Cr–Zr alloys is that the high welding temperature often causes the coarsening of the precipitates, resulting in lower joint strength. Various strategies were studied to reduce the welding temperature below the aging temperature for limiting the precipitate coarsening. The results showed that great challenges existed in reducing the friction stir welding (FSW) temperature below the peak-aging temperature of Cu–Cr–Zr alloy (420–480 °C) without using coolant. Through softening the Cu–Cr–Zr alloys to the supersaturated solid solution state prior to FSW, the peak temperature during FSW of Cu–Cr–Zr alloy under water was reduced to ∼481 °C, which is close to the aging temperate of the Cu–Cr–Zr alloy. After post-weld aging heat treatment, the stir zone exhibited higher hardness than the peak-aged Cu–Cr–Zr alloy due to the combination of the high density of precipitates 10.5 nm in diameter and refined grains 0.65 μm in diameter, enabling the achievement of high joint strength equal to the peak-aged base metal. In addition, the FSW zone also exhibited a high electrical conductivity of 88.9% IACS, which is higher than that of the peak-aged base material (81.0% IACS).

Effect of Surface Modification of Carbon Nanotubes on the Properties of High-Strength and High-Conductivity Copper Matrix Composites

The use of carbon nanotubes (CNTs) as the reinforcing phase to prepare copper-based composite materials can improve the strength and high conductivity of copper-based conductors. In order to analyze the effect of surface oxidation modification on the structural properties of carbon nanotubes and its strengthening effect on composite materials, this article combines heterogeneous copolymerization liquid phase mixing method and spark plasma sintering molding method; prepares the carbon nanotubes/copper composite materials using carbon nanotubes under different oxidation treatment conditions as the reinforcing phase (the volume fraction of carbon nanotubes is 3%); and characterizes the microstructure, mechanical properties, and electrical and thermal conductivity of the composite material. Studies have shown that the tensile strength and hardness of composite materials first increase with the increase of CNT oxidation treatment time and then decrease with the increase of oxidation treatment time. When the oxidation treatment time is 4 h, CNTs are uniformly dispersed in the matrix while maintaining good structural integrity and load-bearing capacity, and the composite material has the highest mechanical properties. The tensile strength of the composite material made of 80‐ nm CNTs reaches 452.4 MPa, which is 1.6 times that of pure copper, and the hardness reaches 127.4HV, which is twice that of pure copper. The electrical conductivity and thermal conductivity of the composite material first increase with the increase of the oxidation treatment time of carbon nanotubes and then decrease with the increase of the oxidation treatment time. The 80 nm CNT reinforced composite material has better CNT dispersion performance and higher conductivity than that of 15 nm CNT preparation. The electrical conductivity of the composite material reaches the maximum value of 92% IACS when the CNT oxidation treatment time is 4 hours, which is 95% of the pure copper sample, and the electrical conductivity is significantly better than that of the CNT/Cu composite material and copper alloy prepared by other methods. The thermal conductivity of composite materials is lower than that of pure copper. The thermal conductivity of carbon nanotubes with an oxidation treatment time of 2 h decreases most obviously, indicating that the thermal resistance generated by the interface and agglomeration phases in the composite material affects its thermal conductivity.

Pure Alloy Additive or Preliminary Alloy: A Comparative Study on Obtaining High-Strength Copper Magnesium Alloys Designed for Electrical Power Systems

Due to the increasing demand for electrical energy in modern society, there is a huge requirement for conducting materials and, due to the development of electromobility, this demand is forecasted to grow each year. This is one of the reasons why copper and copper alloys manufacturing and processing industries tend to evolve and improve. One of the improvement paths is the design of new conducting materials for electrical power systems, electrical energy transmission, and energy storage systems. This paper presents a comparative study on obtaining high-strength copper magnesium alloys in terms of the alloy additive used during the metallurgical synthesis process, because this is a crucial, initial element in obtaining the final conducting product, such as wires. The obtained ingots were tested in terms of their chemical composition, and mechanical and physical properties. The provided results prove that there is a significant increase in the materials’ hardness (and thus the ultimate tensile strength), and a slight decrease in density, impact resistance, and electrical conductivity, as the Mg content increases. Scanning electron microscopy (SEM) and phase analysis were additionally conducted in order to determine the distribution and origin of Mg precipitations. Collectively, the results show that the CuMg alloys may successfully replace other alloys, such as CuNiSi or CuZn, as carrying and conducting materials because their properties are superior to those of the aforementioned materials.

High Throughput Calculation and Screening of High Strength and High Conductivity Cu-Cr-Sn Copper Alloy

In this paper, based on the first principles, the exchange correlation functional (GGA) and modified functional (PBE) are used for the calculation of Cu-Cr-Sn high strength and high conductivity copper alloy. The cloud high-throughput cloud computing and screening platform such as Matcloud and cluster expansion method are mainly used. Starting from the most basic components of micro atoms, electrons, ions and energy bands, the high-throughput crystal structure modeling and screening optimization algorithm are adopted, The electronic structure, electromigration and diffusivity of the matrix and the second phase of the material were studied. The theoretical criteria for the collaborative optimization and control of the key performance parameters of the matrix and the characteristic microstructure were established. The characteristic microstructure and material component sequences with excellent mechanical, electrical and thermodynamic properties were predicted and screened.

High Strength and High Electrical Conductivity C70250 Copper Alloy with Fibrous Structure Reinforced by High Density, Multi-Scale Nano-Precipitates and Dislocation

High Strength and High Electrical Conductivity C70250 Copper Alloy with Fibrous Structure Reinforced by High Density, Multi-Scale Nano-Precipitates and Dislocation

Dynamic Tensile Properties of Clay Bricks

It is commonly known that materials behave differently under static and dynamic loads. There is still a lack of understanding of dynamic material properties of clay bricks. Our previous study investigated the dynamic compressive properties of clay bricks. This paper focuses on the dynamic tensile properties of clay bricks. Quasi-static and dynamic tests are carried out on three types of clay bricks, i.e., high-strength Copper Brown, mid-strength Limestone Hue, and low-strength Common Solid bricks. Both direct tensile test and indirect split-tensile test (Brazilian disc test) are conducted to determine the brick tensile properties at various strain rates. Dynamic tensile strength, corresponding failure strain, Young's modulus at strain rates between 1.33 × 10−6 s−1 and 26 s−1 are determined. Correlation between dynamic split-tensile strength and dynamic direct tensile strength is examined and a conversion relationship is proposed. The results are compared with existing data on brick, mortar and concrete. An empirical formula of DIF (dynamic increase factor) for brick tensile strengths at different strain rates are derived for easy and accurate engineering analysis and numerical modelling of clay brick response under dynamic loading.

Additive manufacturing of high strength copper alloy with heterogeneous grain structure through laser powder bed fusion

Laser powder bed fusion (L-PBF) additive manufacturing was utilized to fabricate high-strength copper (Cu) alloys through inoculation of pure Cu powder with cobalt (Co) submicron particles. It was found that when the addition level of Co is lower than its maximum solid solubility in Cu (4.75 wt.%), the microstructure of Cu-Co alloys is characterized by coarse columnar grains. Further addition of Co over 4.75 wt.% led to a heterogeneous grain structure, with large equiaxed grains or columnar grains near the centers of melt pools whereas ultrafine equiaxed grains sitting on the melt pool boundaries. Microstructure characterization showed that the in-situ formed dual phase nanoparticles with Co shell and cobalt oxide (CoO) core acted as heterogeneous nucleation sites of Cu, which allowed ultrafine, equiaxed grains to form. The heterogeneously structured as-built Cu-Co alloy achieved a tensile strength of 381.4 ± 2.9 MPa and an elongation of 31.6 ± 1.3%. Co nanoprecipitation driven by post L-PBF heat treatment further increased the tensile strength of the Cu-Co alloy up to 491.1 ± 12.6 MPa without notably sacrificing the ductility. The combination of high strength and high ductility distinguishes Cu-Co alloys from most conventionally and additively manufactured Cu alloys. This study shows a strategy to produce Cu alloys with high performance through remarkable grain refinement by heterogeneous nucleation.

Experimental study of the simultaneous effects of severe plastic deformation and secondary radial strain on copper

Due to the widespread use of copper wires in electrical power transmission, the need for raw materials with a homogeneous structure and high strength while maintaining their conductive properties is of high importance. The present study investigates the production of copper wire with improved mechanical properties and homogeneous microstructure due to its nanometre-sized structure. Therefore, the commercial pure copper specimens were subjected to severe plastic deformation (SPD) by means of equal channel angular pressing (ECAP) during four steps at ambient temperature. Due to the creation of a structure with elongated grains in the ECAP process, the deformed specimens were subjected to the direct extrusion operations; thus, a more homogeneous structure was created in them due to the appearance of a secondary radial strain. The obtained results indicate that by applying the simultaneous effects of SPD and direct extrusion on the microstructure, the mechanical properties such as strength and hardness have improved significantly, while the electrical conductivity of pure copper decreased slightly. The outcome can be used as an alternative to current methods for producing high-strength copper wires with suitable electrical conductivity properties.

Additive Manufacturing of High Strength Copper Alloy With Heterogeneous Grain Structure Through Laser Powder Bed Fusion

The low laser processability of pure copper (Cu) commonly causes high porosity, and therefore low strength of additively manufactured (AMed) Cu parts. The current work reports an effective approach to solve this problem through inoculation of pure Cu powder with cobalt (Co) submicron particles. Co addition enabled increase in laser absorptivity, and therefore dense Cu was fabricated through laser powder bed fusion even though typical AM featured coarse columnar grains were produced when Co addition was 4 wt.% or less. Significant grain refinement with heterogeneous grain structure (HGS) was achieved when the addition level was greater than the maximum solid solubility of Co in Cu (4.75 wt.%), such as 6 and 8 wt.%. HGS is characterized with ultrafine equiaxed grains close to melt pool boundaries and coarser equiaxed grains or columnar grains near centres of melt pools. Heterogenous nucleation of Cu near melt pool boundaries, where were associated with larger thermal undercooling due to faster cooling rate, was responsible for the formation of ultrafine equiaxed grains. In contrast, heterogeneous nucleation near centres of melt pools was suppressed. Detailed substructure examination indicated that heterogenous nucleation occurred on dual phase nanoparticles containing Co shell and cobalt oxide (CoO) core. The higher affinity of Co to oxygen caused formation of CoO. HGS of Cu significantly improved both strength and ductility. After direct ageing at 600°C for one hour, a tensile strength of 491.1±12.6 MPa, elongation of 27.3±2.5% and electrical conductivity of 61.5% IACS (International Annealed Copper Standard) were achieved.

High-temperature deformation behavior of a novel high strength and high elasticity Cu–20Ni–20Mn–0.3Nb–0.3Cr–0.1Zr alloy

The elongation of high-strength copper alloy with tensile strength over 1300 MPa is generally less than 3%. In this paper, a novel Cu–20Ni–20Mn-0.3Nb-0.3Cr-0.1Zr(wt.%) alloy was prepared, of which the tensile strength, elastic modulus and elongation is 1445 MPa, 147 GPa and 6.8%, respectively. The flow stress strain and microstructure evolution during high temperature deformation at different strain temperatures and strain rates are studied to obtain the high temperature deformation law and dynamic recrystallization mechanism of the alloy. The research shows that the flow stress of the design alloy increases rapidly with the increase of the strain during the initial stage of thermal deformation. When the strain rate is higher and the strain temperature is lower, the peak value of flow stress is larger. The thermal activation energy of the designed alloy is 353.31 kJ/mol. When the strain temperature is 650°C–720 °C and the strain rate is 0.1s−1-5s−1, the alloy is in the hot deformation instability zone. The optimal deformation temperature of the alloy is 750°C–850 °C. When the deformation temperature reaches 800 °C, dynamic recrystallization occurs in the alloy structure. When the design alloy is deformed at a temperature of 850 °C, the recrystallization power of the alloy is mainly the deformation stress energy, and the degree of recrystallization mainly depends on the strain rate. At this time, the faster the strain rate is, the more obvious the recrystallization effect is, and even the recrystallization grain growth will occur.

Severe Plastic Deformation of Copper, Binary Cu-Zn Solid-Solution Alloys, and High-Strength Brass by High-Pressure Torsion

Severely-deformed high-strength brasses were investigated by leveraging high-pressure torsion (HPT) processing in order to obtain more enhanced mechanical properties of copper alloys. Pure copper, binary Cu-Zn solid-solution alloys and high-strength brasses including aluminum and manganese additions were selected for experiments. For comparison of these materials, zinc equivalent parameter was used. These materials were subjected to the HPT processing, followed by hardness tests and tensile tests. The maximal hardness value of the nanostructured high-strength brass with β phase matrix was reached 420 HV. The HPT processed high-strength brass with β phase matrix showed significant increase in the yield stress and tensile strength with sacrificing ductility. The tensile specimen of the high-strength brass with β phase matrix was fractured before initiation of necking. It was found that utilizing β phase matrix is also beneficial for controlling enhanced strength of high-strength copper alloys for not only casting process but also severe plastic deformation.

Stress relaxation behaviors and mechanical properties of precipitation strengthening copper alloys

In order to measure cantilever bending stress of elastic alloys during stress relaxation experiment, a homo-made apparatus has been developed. The mechanical properties and stress relaxation resistances of three high strength copper alloys have been investigated. Considering different experimental conditions, the Cu-Ni-Sn alloys exhibit the optimum stress relaxation resistance. The mechanisms of stress relaxation and precipitation strengthening have been discussed. The hardness is recommended to be a critical parameter which can be used to evaluate the stress relaxation resistance simply. Because the interactions between precipitation particles and dislocations which influence the hardness also affect the dynamic recovery of mobile dislocations during stress relaxation. Finally, two effective methods have been proposed to slow down the stress relaxation in the copper alloys.

Microstructure and properties of a novel ultra-high strength, high elasticity and high plasticity Cu–20Ni–20Mn-0.3Nb-0.3Cr-0.1Zr alloy

The elongation of high-strength copper alloy with tensile strength over 1300 MPa is generally less than 3%. In this paper, a novel Cu–20Ni–20Mn-0.3Nb-0.3Cr-0.1Zr (wt.%) alloy with high strength, high elasticity and high plasticity was prepared. Its tensile strength, elastic modulus and elongation is 1445 MPa, 147 GPa and 6.8%, respectively. On the basis of Cu–20Ni–20Mn alloy, microalloying Nb, Cr, Zr elements were added to restrain discontinuous precipitation and improve the properties of the alloys. By matching reasonable heat treatment process, a fine and highly uniform grain structure was obtained, which is the main reason for the increase of elongation. TEM and 3DAP results suggested that a large number of nanoscale NiMn precipitates are the main source of high strength in the alloy. The designed alloy has excellent comprehensive properties, which can be used for the preparation of precision sensing parts, elastic components.

Development of Lead-Free High-Strength Copper Alloy

Development of Lead-Free High-Strength Copper Alloy

Applicability of friction-assisted tube straining method to produce high-strength copper tubes

This paper shows the capability of friction-assisted tube straining (FATS) method to fabricate high-strength long tubes. For this reason, copper tubes were successfully processed via 1–7 passes of the FATS. Mechanical properties of the processed tubes were investigated via longitudinal and peripheral tensile tests. Polarize microscopy and scanning electron microscopy were executed to study microstructure evolutions. Finite element analysis was used to determine strain and temperature fields. Results show significant improvement in mechanical properties where flow stress, ultimate tensile stress, and microhardness increased 9.3, 1.8, and 2 times more than the initial values. Average grain size of the FATSed tube was significantly decreased to 1.4 μm from an initial value 30 μm after 7 passes. Investigation of the tensile properties of the longitudinal and the peripheral samples resulted in a maximum 19% anisotropy which was considerably improved comparison with the same SPD methods.

High-Strength Cu–Ta–W Composite

High-strength copper conductor composites have been used in pulse magnet applications and as internal reinforcement in superconductor wires. The required property is high strength while maintaining high conductivity. Heavily worked pure copper has a strength of 450-500 MPa. Increasing the strength of copper by alloying additions without affecting the conductivity drastically is a significant challenge. Mixing pure copper with a higher modulus, higher strength tantalum alloys is an option to meet the challenge. This work reports on the use of a tantalum-tungsten alloy to strengthen high-purity copper through a multi-filament approach. The tantalum tungsten has a high modulus and very low solubility in copper. A composite wire containing 133 filaments of Ta-W (25% by volume) has a conductivity of 80% International Annealed Copper Standard and ultimate tensile strength of over 650 MPa with a modulus over 140 GPa. The wire has good ductility and toughness. These results are comparable or better than current options, and the potential to improve this product is explored.

고강도 구리 라이너가 적용된 종횡비 2.73 성형작약탄의 제트형성 및 표적관통 특성에 대한 수치해석 연구

고강도 구리 라이너가 적용된 종횡비 2.73 성형작약탄의 제트형성 및 표적관통 특성에 대한 수치해석 연구

Mechanochemical processing of Cu-Y2O3 alloy by MA-HIP for heat sink materials application

Fabricating high-strength copper (Cu) alloys with high conductivity are extremely desirable for a range of applications, such as heat sink materials in fusion reactors. This study reports an in-situ mechanochemical process combining Mechanical Alloying (MA) and Hot Isostatic Pressing (HIP) to prepare Cu-Y2O3 composites. It is found that MA of Cu and Y powders led to formation of a Cu(Y) solid solution, accompanied by lattice expansion, grain refinement, melting point decline, and hardness increase. When the Cu(Y) solid solution powder was milled with CuO powder, reaction between Cu(Y) and CuO occurred, with a shrinkage of the lattice, and increase in both the melting point and hardness. The MA powder was then consolidated by HIP, and the existence of Y2O3 was confirmed by X-ray diffraction. An unexpected decrease of the electrical conductivity of the consolidated bulk material was observed and the reason was analyzed. This study will provide helpful information to optimize the preparation of copper-based materials through process control.