High Conductivity Copper Alloys Research Articles

Microstructure and mechanical properties of Cu-Cr-Zr alloy prepared by electron beam additive manufacturing and laser-MIG hybrid welding

Cu-Cr-Zr alloys are widely used as medium-strength and high-conductivity copper alloys in aerospace, transportation and electronic information fields. The application of additive manufacturing technology is expected to realize the preparation of Cu-Cr-Zr alloy parts with complex structure and superior property. However, the commonly used laser additive manufacturing technology is not applicable to the preparation of copper alloys due to its intrinsic high reflection to laser. In this study, we adopted two technologies, i.e., electron beam additive manufacturing (EBAM) and laser-metal inert gas hybrid welding (laser-MIG), for the preparation of Cu-Cr-Zr alloys. Finite element simulation was employed to simulate the temperature field and residual stress field of the material during solidification. The microstructure, relative density, microhardness, tensile properties and electrical conductivity of the as-fabricated samples were characterized. The results showed that samples with better moldability were obtained by both methods at a line energy density of 600 J/mm. In the top area, both methods exhibit medium-sized equiaxed grains with more precipitated phases, showing the best comprehensive properties. The EBAM method demonstrates superior formability, better relative density and electrical conductivity due to more stable temperature field changes. On the other hand, the laser-MIG method obtains finer grains and higher mechanical properties because of a faster cooling rate, but leads to a decrease in relative density and electrical conductivity. This study presents new experimental data for Cu-Cr-Zr alloys prepared by EBAM and laser-MIG methods, contributing to extend the application of additive manufacturing in the preparation of Cu alloys.

Additively manufactured copper alloy with heterogeneous nanoprecipitates-dislocation architecture for superior strength-ductility-conductivity synergy

Employing a single strategy that overcomes the strength-ductility-conductivity trade-off in copper alloys has proven to be challenging. In this study, we introduced a novel heterogeneous nanoprecipitate–dislocation (HND) architecture in CuCrNb alloy consisting of a multi-modal core–shell grain structure and an interconnected dislocation network pinned by abundant nanoprecipitates. Our CuCrNb-HND alloy exhibited superior strength–ductility synergy at both room and elevated temperatures. In particular, aging treatment-induced high-density coherent Cr secondary nanoprecipitates into the HND skeleton endowed the CuCrNb-HND450 alloy with a high tensile strength of over 1 GPa and a conductivity of ∼50%, surpassing those of most of the reported additively manufactured copper alloys. An in situ transmission electron microscopy heating experiment revealed the superior thermal stability of the HND architecture. Hierarchical strengthening contributed to the enhancement of mechanical properties. At the micrometer scale, the harmonic grain structure with a strong fine-grained shell and a ductile coarse-grained core effectively improved mechanical properties by suppressing localized plastic deformation. At the nanometer scale, the synergistic effect of the nanoprecipitate–dislocation network further improved the alloy strength by slowing down dislocation movement. Overall, our proposed HND architecture provides an efficient pathway for developing high-strength and high-conductivity copper alloys.

First-principles study on the high-strength and high-conductivity modification mechanism of C7035 copper alloy by Ni, Si, and Co solid solution

In order to investigate the effects of matrix solid solution, precipitate phases, and microscale interfaces on the mechanical and electrical properties of copper alloys, we employed first-principles calculations based on density functional theory study aimed to understand how alloying elements enhance the strength and conductivity of copper. The results demonstrated that doping Co atoms into the copper matrix using the Dop2 structure model exhibited the most significant improvement in both mechanical and electrical properties. The Young's modulus was doubled compared to pure copper, and the hardness increased several times. The electrical conductivity reached 59.8 % of the International Annealed Copper Standard (IACS), showing a 6.6 % enhancement compared to Si doping. To validate computational results, we conducted experiments that confirmed the accuracy of the predicted mechanical and electrical properties. Furthermore, the introduction of Co effectively reduced electron losses at the interface between the precipitate phase and the copper matrix. The electron transmission rate through the Co2Si (211)/Cu (111) interface reached 78.6 %, representing a 94.1 % improvement compared to the Ni2Si (111)/Cu (111) interface. In conclusion, Co can simultaneously enhance the mechanical and electrical properties of Cu–Ni–Si alloys, providing theoretical guidance for the design and fabrication of high-strength and high-conductivity copper alloys.

Intelligent Design of High Strength and High Conductivity Copper Alloys Using Machine Learning Assisted by Genetic Algorithm

Intelligent Design of High Strength and High Conductivity Copper Alloys Using Machine Learning Assisted by Genetic Algorithm

Study on wear properties of high hardness and high thermal conductivity copper alloy for crystallization roller

The crystallization roller in thin strip continuous casting combines the cooling function of the plate crystallizer with the rolling function of the roll, thereby significantly enhancing process efficiency. This also imposes higher demands on the thermal conductivity and hardness of the crystallization roller. During the utilization of the crystallization roller, as it comes into contact with the billet, the base material must exhibit exceptional wear resistance. The thermal conductivity and mechanical properties of high-strength beryllium copper alloy C17200 and traditional crystallization material CrZrCu alloy C18150 were assessed at various temperatures using a laser thermal conductivity meter (LFA-427) and microhardness meter (ZD-HVZHT-10), respectively. Detailed analysis confirms the potential suitability of C17200 as an alternative material for crystallization rollers. The hardness of C17200 was twice that of C18150 while maintaining the original thermal conductivity. The wear characteristics of C17200 were investigated at room temperature (25 °C) and simulated operating conditions (300 °C) using a reciprocating wear tester (MZF-1). Additionally, the wear mechanism of C17200 at different temperatures was studied using scanning electron microscopy (SEM). The findings demonstrated that C17200 exhibited favorable wear resistance even at a temperature of 300 °C, thereby satisfying the performance criteria for the crystallization roller during operational usage.

Influence of the thermal conductivity of different CuCr0.8 substrate state on the formability of laser directed energy deposition Inconel718 single track

One effective method for fabricating liquid rocket engine thrust chambers involves using laser directed energy deposition (LDED) to produce Cu/Ni bimetals by depositing Ni-based superalloys onto a High Strength and High Conductivity (HSHC) copper alloy. However, it is difficult to fabricate strengthening layer to the surface of HSHC Cu alloy due to its extremely high thermal conductivity. This paper investigates the influence of states of the HSHC CuCuCr0.8 substrate e.g., as-built of LPBF, rolled and annealed, and direct age after LPBF at 480 °C for 4 h, on the formability of In718 single track by LDED. The results indicate that the thermal conductivity is significantly influenced by the state of the HSHC CuCuCr0.8 substrate. At room temperature and 300 °C, the order of the thermal conductivity from low to high is as-built of LPBF, rolled and annealed, and direct age after LPBF at 480 °C for 4 h, while at 500 °C, the as-built of LPBF substrate has the lowest thermal conductivity, while the rolled and annealed substrate has the largest thermal conductivity. Thermal conductivity has a significant effect on the formability of LDED. The LPBF-ed substrate has the best formability, with a minimum Ra value of 9.72 ± 0.12 μm, a maximum deposition depth of 193.00 ± 4.32 μm, and a minimum grain size of 5.2 ± 2.6 μm because of its smallest thermal conductivity. These findings demonstrate that using an as-built LPBF-ed substrate can improve the LDED formability of the In718 single track compared with the other two substrates. This paper presents a new approach for LDED on alloy surfaces with high thermal conductivity.

CALPHAD-assisted composition and processing design of high-strength and high-conductivity copper alloy

In this work, a Cu–Cr–Ag–Mg–Sn alloy was developed assisted by a CALPHAD technique, by which a suitable chemical composition (Cu-0.5Cr-0.1Ag-0.05Mg-0.05Sn) and processing parameters were efficiently designed. The achieved alloy exhibited yield strength and conductivity values of 642 MPa and 74.2% IACS, respectively, which greatly surpassed the commercial C18150 alloy. Transmission electron microscopy observation demonstrated that such a good comprehensive performance was attributed to numerous nano-scale Cr precipitates that possessed a strong coherent relationship with the Cu matrix. Further microstructure characterizations demonstrated that these beneficial Cr precipitates were associated with subgrain boundaries in the alloy introduced by a cold-rolling→short-time secondary solid solution. Atom probe tomography analysis demonstrated that Sn atoms that readily attached to the surfaces of Cr precipitates.

Phase Equilibria, Thermodynamics and Solidified Microstructure in the Copper–Zirconium–Yttrium System

A copper alloy with the addition of zirconium and yttrium is an attractive high strength and high conductivity (HSHC) copper alloy. The study of the solidified microstructure, thermodynamics and phase equilibria in the ternary Cu-Zr-Y system is expected to provide new insight into designing an HSHC copper alloy. In this work, the solidified and equilibrium microstructure and phase transition temperatures in the Cu-Zr-Y ternary system were studied by X-ray diffraction (XRD), electron probe microanalysis (EPMA) and differential scanning calorimeter (DSC). The isothermal section at 973 K was experimentally constructed. No ternary compound was found, while the Cu6Y, Cu4Y, Cu7Y2, Cu5Zr, Cu51Zr14 and CuZr phases substantially extended into the ternary system. According to the experimental phase diagram data from the present work and the literature, the Cu-Zr-Y ternary system was assessed using the CALPHAD (CALculation of PHAse diagrams) method. The isothermal sections, vertical section and liquidus projection calculated by the present thermodynamic description agree well with the experimental results. This study not only establishes a thermodynamic description of the Cu-Zr-Y system, but also contributes to the design of a copper alloy with the required microstructure.

Precipitate Size in GRCop-42 and GRCop-84 Cu-Cr-Nb Alloy Gas Atomized Powder and L-PBF Additive Manufactured Material

Laser powder bed fusion (L-PBF) of Glenn Research Copper 42 or 84 (GRCop-42 or GRCop-84) produces a Cr2Nb precipitation-hardened high-conductivity copper alloy with tensile strength superior to other competing copper alloys. Precipitate diameters within GRCop-42 gas-atomized powder increase with powder diameter due to slower cooling rates, however, unlike GRCop-84, no threshold diameter above which extensive precipitate agglomerations form was observed in GRCop-42. Large Cr2Nb crystals were observed in GRCop-42 powder particles, implying formation within the crucible melt. A consistent precipitate volume of ~7% over a range of powder particle diameters indicated a consistent atomization process. Occasional voids were observed in GRCop-42 powder. Precipitate size was refined in L-PBF GRCop-42 to a greater extent than in GRCop-84, improving Orowan strengthening, however, this benefit was lost after heat treatment due to greater coarsening of precipitates. Precipitates in GRCop-42 accumulated on grain boundaries during heat treatment to a greater extent than in GRCop-84.

Effects of pre-aging on microstructure and properties of Cu-Ni-Si alloys

Thermal-mechanical treatment is critical for the synthesis of Cu-Ni-Si alloys with high strength and conductivity. In this work, a high-temperature/short-time pre-aging treatment (600 °C, 10 min) was introduced to the thermomechanical processes of Cu-Ni-Si alloys, and the effects of pre-aging on the microstructure and properties of the alloy were investigated in detail. The results showed that Ni2Si particles precipitated from the matrix during pre-aging, promoting the formation of a nanoscale microstructure after cold rolling (cold rolled by 85% reduction). The pre-precipitated Ni2Si particles that formed during pre-aging consumed part of the dissolved Ni and Si solutes in the copper matrix, resulting in a higher initial conductivity before the final aging process. The grain refinement effect and high deformation-stored energy benefited the subsequent final aging by lowering the aging temperature and improving the alloys’ high performance. This provided a guideline for the design and development of high-strength, high-conductivity copper alloys. The strengthening mechanism and corresponding microstructure evolution are also systematically investigated. The pre-existing Ni2Si particles strongly hinder the mobility of dislocations during cold rolling and retard the recovery of sub-structures at room temperature, leading the grain refinement in the nanoscale.

Investigating the influence of the scanning rotation angle on the microstructure and properties of LPBFed CuCr0.8 alloy

The fabrication of high-strength and high-conductivity (HSHC) copper alloys by laser powder bed fusion (LPBF) has attracted great interest in recent years. Owing to the excellent strength and high electrical and thermal conductivity of HSHC copper alloy. Moreover, the characteristics of LPBF are suitable for fabricating HSHC. In this paper, the QCr0.8 copper alloy samples with four scanning rotation angles of 0°, 67°, 90°, and 105° were fabricated by LPBF using the high laser power of 2000 W. The results indicate that the scanning rotation angles have no significant influence on the relative density. When the scanning rotation changes to 0°, 67°, 105°, and 90°, the order of the grain size is from large to small. With the 90°scanning rotation angle, the as-built sample has the smallest ultimate tensile strength (UTS) and electrical conductivity. After direct aging, its UTS up to 468.0 Mpa and electrical conductivity is up to 98.3 %IACS. Equally, as a result of precipitation strengthening, the UTS of samples with different scanning rotation angle all increase significantly. This study is to provide theoretical guidance and reference for the selection of scanning rotation angles in the HSHC alloy fabrication process.

Achieving high strength and high conductivity synergy through hierarchical precipitation stimulated structural heterogeneities in a Cu-Ag-Zr alloy

Cu alloys can be plastically deformed to reach ultra-high strength, but often at an expense of their electrical conductivity. Here we report that the introduction of hierarchical precipitations and the resultant microstructural heterogeneities at different scales could overcome the strength-conductivity tradeoff in Cu-Ag-Zr alloy. The intrinsic particle size dependent precipitation behavior, owing to the different cooling rate during powder atomization, has been inherited after hot isostatic pressing (HIP) of powders into bulk sample. The following cold rolling and aging created multi-scale structures with the sub-micron particles at grain boundaries and sub-micron-to-nano scale precipitates in the grain interior. Those introduced heterogeneous precipitate configurations also altered the evolution of deformation structures during cold rolling and aging, with partially recrystallized grains embedded in highly deformed matrix featured by high density of dislocation and substructures, which results in an excellent combination of tensile strength (704 MPa), electrical conductivity (88.7% IACS), and tensile elongation (14.9%). Besides, no significant coarsening in the micro-nano structures is observed after annealing at 450 °C for 1 h. The findings in this work proposed a novel approach for designing high-strength, high-conductivity, and high-thermal stability copper alloys based on hierarchical precipitation-stimulated structures at nano-to-micron scale.

Strengthening caused by precipitates with different morphologies in Cu–Cr–Ti alloys: The role of dislocation bending angle

Addition of a small amount of Ti can significantly improve strength of Cu–Cr alloys. Previous work found that addition of Ti produced both spherical and cubic-shaped Cr particles. In this work, the hindering effect of Cr particles with different morphologies on dislocation was further studied. Transmission electron microscopy and high-resolution transmission electron microscopy were used to observe the bending angle of dislocations cutting through precipitated phase particles at about 108° or 54°. The angle of dislocations cutting through the spherical particles was 108° and that of the cubic particles was 54°. Theoretical calculations of dislocation bending angle to enhance strength determined that the bending angle of dislocations cutting cubic particles is about 54°. This study provides new insights for the design and preparation of high-strength and high-conductivity copper alloys.

Effects of Si addition on properties and microstructure of CuCrZr alloy

In order to develop high-strength and high-conductivity copper alloys with better comprehensive properties, the effects of Si addition on the mechanical properties, electrical conductivity and microstructure of CuCrZr alloy were investigated in this paper. The addition of Si element can improve the hardness, strength and ductility of CuCrZr alloy. The optimal peak aging parameter for CuCrZrSi alloy is 430 °C for 3 h, the hardness 228.92 HV, the tensile strength 646.76 MPa, and the elongation after fracture 10.67%. Compared with the CuCrZr alloy under the same process, the mechanical properties are increased by 10.3%, 11.9% and 16.9%, respectively. The conductivity is 4 ± 1%IACS lower than that of the sample without Si addition. The addition of Si element refines the deformation substructure and produces more Σ3n (n = 1, 2, 3) grain boundaries, thus providing more nucleation sites and higher driving forces for the precipitation phases. In both CuCrZr and CuCrZrSi alloys, the fine precipitation phases (<10 nm) fcc-Cr phase and orthorhombic-Cu8Zr3 phase, together with coarse precipitation phases (>100 nm) bcc-Cr phase and hcp-Zr phase can be observed. The orientation relationship among the two fine precipitation phases and the matrix is (1¯1¯1)[11¯0]Cu∥(1¯1¯1)[11¯0]Cr∥(133)[01¯1]Cu8Zr3. The Si element tends to precipitate together with the Cr phase and Zr phase, and acts to refine and spheroidize the precipitation phases.

First Principle Calculation and Thermodynamic Analysis of Coexisting Phase of Cu-Cr-Sn Copper Alloy

Based on the idea of material genetic engineering, according to the innovative design of the whole material chain and taking high-strength and high conductivity copper alloy as the research object and carrier, this paper carries out high-throughput integrated calculation and design methods such as alloy characteristic microstructure, interface chemistry, thermodynamics and kinetics, establishes the prediction model of material composition structure process performance relationship, and realizes the high-throughput preparation and characterization technology of materials, Form a low-cost and rapid development capability oriented by application objectives. In this paper, the mixed matrix and characteristic microstructure sequence are optimized by high-throughput calculation, the thermodynamic and kinetic conditions of material preparation and synthesis are analyzed, and the phase diagram and solidification technology are calculated by CALPHAD to optimize the content, morphology and distribution of characteristic microstructure in the alloy. By designing polycrystalline and peritectic platforms, the microstructure type, morphology and content of characteristic microstructure can be controlled. At the same time, the type, content and distribution of the second phase are regulated by multi-element alloy equilibrium calculation phase diagram and non-equilibrium solidification path calculation, so as to realize the integrated calculation of materials and the selection of composition and process sequence range.

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.

Intelligent Design of High Strength and High Conductivity Copper Alloys Using Machine Learning Assisted by Genetic Algorithm

Intelligent Design of High Strength and High Conductivity Copper Alloys Using Machine Learning Assisted by Genetic Algorithm

Densification Behavior and Microstructure of High Strength and High Conductivity Copper Alloy Fabricated by Selective Laser Melting

Densification Behavior and Microstructure of High Strength and High Conductivity Copper Alloy Fabricated by Selective Laser Melting

A multiphase strengthened Cu-Nb-Si alloy with high strength and high conductivity

There is a challenging trade-off between the high strength and high electrical conductivity in copper-based alloys. Designed Cu-3.65 wt%Nb (CN) and Cu-3.48 wt%Nb-0.11 wt%Si (CNS) alloys were fabricated by vacuum melting and followed by thermal-mechanical treatment. Microstructure evolutions and properties measurements were studied. Results indicate that morphologies of the Nb 3 Si phase in the CNS alloy are solid or hollow regular polygons whose boundaries are parallel to one of Nb 3 Si's crystal faces. The Nb 3 Si's precipitation can effectively improve the strength, while the Nb 3 Si tip is easy to form stress concentration, which leads to crack and failure. The high electrical conductivity of the CNS alloy was because of the decomposition precipitation of Nb and Nb 3 Si during aging treatment. After hot-rolled by 80% at 900 °C, cold-rolled with a strain of 2.30, the ultimate tensile strength of CN and CNS alloys were 488 MPa and 510 MPa, electrical conductivities were 88.06%IACS (International Annealed Copper Standard) and 93.20%IACS, and elongation rates were 9.3% and 7.1%, respectively. These findings reported a new method to fabricate high-strength and high-conductivity copper alloy. • A multiphase strengthened Cu-Nb-Si alloy with high strength and conductivity was fabricated. • Nb 3 Si particles' morphologies are mainly solid or hollow regular polygon and controlled by crystal surface energy. • The Nb 3 Si particles have a stress concentration at the boundary, which caused transverse cracks.

Effects of solid–liquid doping and spark plasma sintering on the microstructure and mechanical properties of Y2O3-doped copper matrix composites

High-strength and high-conductivity copper alloys have a wide range of applications, such as an important electrical contact material. In this work, Cu–Y2O3 composite material was prepared through solid–liquid doping, calcination reduction, and spark plasma sintering. The effect of different yttrium oxide content (1, 3, and 5 wt%) on the microstructure and mechanical properties of the composite was studied. Results showed that the surface of the calcined and reduced copper powder was uniformly covered with yttrium oxide particles. After spark plasma sintering, the relative density of the blocks almost reached 100%. With the increase in yttrium oxide content, the distribution of yttrium oxide transformed from dispersion to agglomeration, and the grain size gradually decreased. There is a good bond between the copper matrix and yttrium oxide, and the particle size of yttrium oxide particles is approximately 150 nm. In terms of mechanical properties, the Cu-3wt.% Y2O3 sample obtained the best comprehensive mechanical properties with strength of 290.1 MPa, hardness of 125.7 HV, and conductivity maintained at a high level of 95% International Annealed Copper Standard (hereinafter called IACS).