Electrical Conductivity Of Cu Research Articles

Arc erosion behaviour of Cu–diamond composites at different load voltages in air atmosphere

ABSTRACT To investigate the arc erosion performance of Cu–diamond composites, Cu–5vol.-% diamond composites were fabricated using the hot-pressing sintering method. Compared to pure copper, Cu–5vol.-% diamond composites exhibited improvements in Brinell hardness of 60.1 HB. The relative density and electrical conductivity of Cu–5vol.-% diamond composites were 97.54% and 83.29% IACS (International Annealing Copper Standard), respectively, with no significant decrease compared to pure copper. The thermal conductivity was 423.48 W·(m·K)−1, showing a slight enhancement. The effect of different load voltages on the arc erosion behaviour of Cu–5vol.-% diamond composites was investigated. Experimental results indicated that as the voltage rose from 3 to 7 kV, the breakdown strength decreased from 7.164 × 106 V m–1 to 2.535 × 106 V m–1, while the arc duration increased from 21.752 × 10−3 s to 28.864 × 10−3 s, and the breakdown current rose from 10.8 to 27.2 A. Additionally, the presence of diamond particles enhanced the viscosity of the molten pool, thus the splashing phenomenon of copper liquid during arc discharge was not obvious, indicating that the material loss was small. Few cracks and holes were detected. The Cu–5 vol.-% diamond composites possess good resistance to arc erosion.

Effect of Cu–Al Ratio on Microstructure and Mechanical Properties of Cu–Al Alloys Prepared by Powder Metallurgy

Cu–Al alloys are widely used in electronics, new energy, and other fields due to the combination of th excellent corrosion resistance and electrical conductivity of Cu and the light weight of Al. In this paper, the powder metallurgy and equal-channel angular pressing compound technology was used to fabricate a Cu–Al alloy joint, which can be used to replace armor. Devices such as an optical microscope, electron scanning microscope, and microhardness scale were used to characterize the microstructure and mechanical properties of the Cu–Al alloys. The finite element analysis software Abaqus was used to analyze stress distribution during equal-channel angular pressing. The results indicated that the microstructure and properties of Cu–Al alloys were closely related to the volume ratio of Cu–Al. The microhardness and tensile strength were significantly increased by increasing the volume ratio of Cu–Al. As the volume ratio of Cu–Al varied from 1:2 to 2:1, the ultimate tensile strength of the Cu–Al alloys increased from 79.9 MPa to 164.9 MPa at room temperature and the microhardness increased from 60 HV to 101 HV. However, the elongation of the Cu–Al alloys hardly changed; this was about 4.4%. Crack initiation occurred at the Cu–Al interface and spread along the bonding surface of the Cu–Al alloys during the tensile process.

Effects of multistage thermomechanical treatment on the microstructure and properties of Cu–Ni–Co–Si–Mg alloy strip by HCCM horizontal continuous casting

Multistage thermomechanical treatment experiments were conducted on Cu–Ni–Co–Si–Mg alloy strip prepared by the Heating Cooling Combined Mold (HCCM) horizontal continuous casting-cold rolling process. Effects of various heat treatments on the microstructure, mechanical properties, and electrical conductivity of the alloy were studied. The strengthening mechanisms and factors influencing the performance of each process has been analyzed. The tensile strength, yield strength, and electrical conductivity of Cu–Ni–Co–Si–Mg alloy can reach 894 MPa, 855 MPa, and 47.1 %IACS after a third-stage of thermomechanical treatment (TTMT). The cold rolling in first-stage of thermomechanical treatment (FTMT) not only caused work hardening of the alloy but also promoted the precipitation of solute atoms and the growth of second phase particles, limiting the increase in strength. Second-stage of thermomechanical treatment (STMT) effectively hindered the excessive growth of second phase particles in FTMT but shortened recrystallization process. The superior performance of Cu–Ni–Co–Si–Mg alloy after TTMT was attributed to dispersive precipitation of Ni, Co, and Si elements as (Ni, Co) 2Si phases in the copper matrix, strengthening the interaction between the precipitates and dislocations. A short process of HCCM horizontal continuous casting-cold rolling-thermomechanical treatment was developed to produce a high strength and highly electrically conductive Cu–Ni–Co–Si alloy strip used in lead frames.

Insights into the Tribological Properties and Electrical Conductivity of Cu–C Coating Under Grease Lubrication

Insights into the Tribological Properties and Electrical Conductivity of Cu–C Coating Under Grease Lubrication

Tailoring the microstructure, mechanical properties, and electrical conductivity of Cu–0.7Mg alloy via Ca addition, heat treatment, and severe plastic deformation

Tailoring the microstructure, mechanical properties, and electrical conductivity of Cu–0.7Mg alloy via Ca addition, heat treatment, and severe plastic deformation

Effect of Microstructure on Strength and Electrical Conductivity of Cu–3.8 wt%Zr Alloy Wires

Effect of Microstructure on Strength and Electrical Conductivity of Cu–3.8 wt%Zr Alloy Wires

High strength and electrical conductivity of nanostructured Cu–1Cr–0.1Zr alloy processed by multi–stage deformation and aging

The effects of equal channel angular pressing (ECAP), multiple cryogenic rolling and aging treatment on the microstructure, mechanical properties, and electrical conductivity of Cu–1Cr–0.1Zr alloy were investigated. The results showed that multi-stage deformation and aging (ECAP at ambient temperature + primary cryogenic rolling 50 % + 450 °C aging for 1h + secondary cryogenic rolling 80 % + 150 °C aging for 1h) can lead to the rational comprehensive performance of Cu–1Cr–0.1Zr alloy with tensile strength of 730 MPa and electrical conductivity of 75.5 % IACS. The microstructure characterization revealed that in the Cu–1Cr–0.1Zr alloy a subject to the multistage deformation and aging, there ultrafine grains, nanotwins, nanoprecipitates and micrometer precipitates constituted the nanostructured state. The increase in tensile strength was mainly attributed to fine grain strengthening and precipitation strengthening, followed by dislocation strengthening due to low temperature deformation. The ECAP resulted in the refinement of grain, and the increased dislocation density. The following primary cryogenic rolling refined the grains up to ultrafine-grained (UFG) size and created nanotwins. The introduction of nano-precipitated phases by intermediate aging pinned dislocations and impeded the motion of dislocation entanglements, allowing the alloy to achieve higher strength. Multi-stage deformation and aging resulted in a higher density of twin boundaries in the nanostructure and dilute solid solution in comparison with one stage treatment. These microstructural features were responsible for the excellent electrical conductivity.

Improved mechanical strength, ductility, and electrical conductivity of Cu–Ni–Si alloys after multi-pass continuous extrusion and aging processes

The manufacture of high strength, high electrical conductivity, and high ductility of Cu–Ni–Si strips in the industry is a challenging problem due to the mutually exclusive relationships among the three properties. However, the results obtained in the present study demonstrated that the trade-offs can be improved by employing a multi-pass continuous extrusion and aging process. The mechanical strength and electrical conductivity increase with the increase of extrusion number before three passes with the help of dynamically occurred recrystallization and precipitation. The yield strength, however, drops after four-pass extrusion, suggesting that a too-high strain deformation during continuous extrusion is not favorable. After aging, alloys that suffer fewer extrusion passes exhibit higher yield strengths, indicating that it is the precipitates rather than the microstructure that dominates the mechanical properties of Cu–Ni–Si alloys. Interestingly, the fracture elongation after aging for alloys experienced more pass number increases, which can be attributed to the refined grain size and reduced dislocation densities. After a two-pass continuous extrusion and aging process, the tensile strength and fracture elongation can reach 629 MPa and 16.5%, respectively, increasing approximately by 28.8% and 13.4% compared with those before aging. It is therefore significant to design an appropriate deformation process (strain) for continuous extrusion to obtain high strength, high conductivity, and high ductility Cu–Ni–Si strips.

Properties and mechanism of Cu(OH)2 nanoarray reinforced cement composites

This experiment investigates the effect of Cu(OH)2 nanoarray on the properties of cementitious materials. Cu(OH)2 nanoarray is a novel nanomaterial with excellent electrical conductivity and chemical stability. At present, the interaction mechanism between Cu(OH)2 nanoarray and cementitious materials has not been explored. In this paper, the effect of Cu(OH)2 nanoarray on the properties of cement mortar was investigated by testing the mechanical strength and electrical conductivity of Cu(OH)2 nanoarray. The microstructure of Cu(OH)2 nanoarray cement mortar and the development of hydration products were analyzed using XRD, SEM, EDS and MIP tests. The results showed that when 0.5% Cu(OH)2 nanoarray was added, the 28d compressive strength and flexural strength of the cement mortar increased by 50.29% and 41.28%, respectively, and its electrical resistivity decreased by 50%. The Cu(OH)2 nanoarray optimized the mechanical strength and workability of the cement mortar by modulating the hydration products and improving the microstructure.

Optimizing strength and electrical conductivity of Cu–Fe–Ti alloy by pre-aging treatment

Pre-aging treatment before cold rolling and final aging was introduced to optimize the mechanical properties and electrical conductivity properties of Cu-0.75Fe-0.35Ti alloy. The alloy was pre-aged at 540 °C for 6 h, then cold rolled with thickness reduction of 80%, followed by aging at 460 °C for 2 h (SARA). Vickers hardness, electronic conductivity and uniaxial tensile tests were conducted to measure the mechanical and electrical conductivity properties. Electron backscatter diffraction and transmission electron microscope were used to characterize the microstructural evolution. The results showed that the hardness, tensile strength and electrical conductivity of SARA were up to 198.2 ± 4.8 HV, 622.6 ± 6.3 MPa and 63.8% IACS, respectively, which were superior to those achieved without pre-aging. The enhanced mechanical properties of SARA were attributed to an increase in low angle boundaries (LABs), geometrically necessary dislocation (GND) density and volume fraction of precipitates, while the favorable electrical conductivity was ascribed to the enhancement of precipitation and resultant matrix purification.

Mechanical Strength and Electrical Conductivity of Cu–In Solid Solution Alloy Wires

Mechanical Strength and Electrical Conductivity of Cu–In Solid Solution Alloy Wires

Investigation on the dual-phase co-deformation behavior and strengthening mechanism in cold-drawn Cu–20Fe alloy

In this work, cold drawing deformation was applied aiming to achieve a good combination of strength and electrical conductivity of Cu–20Fe alloy, and also such underlying mechanisms for microstructure evolution and strengthening, as well as variation in conductivity were clarified. It is also found that both Cu matrix grains and Fe-rich dendrites can be significantly refined and transformed into fibrous structure with increasing of drawing strain. The average size of Cu grains and thickness of Fe fiber are 0.47 ± 0.05 μm and 25 ± 5 nm, respectively for alloy subjected to the drawing strain of η = 5.78. In addition, the Fe dendrites exhibit a strong <110> fiber texture, while the corresponding Cu matrix forms a <111> fiber texture. It is demonstrated that the excellent properties with the yield strength of 1173 MPa and the electrical conductivity of 41 %IACS can be reached for cold-drawn Cu–20Fe alloy. In addition, the quantitative analysis on strengthening contributions shows that the high strength of as-drawn Cu–20Fe alloy is dominantly originated from high-density Fe fibers. Meanwhile, the lower electrical conductivity is ascribed to the high solute Fe content and high-density Cu/Fe heterogeneous phase interface.

Effects of Co/Si Atomic Ratio on Hardness and Electrical Conductivity of Cu–Co–Si Alloys

Cu–Co–Si alloys are being intensively studied as alternative candidates for Cu–Ni–Si alloys for integrated circuit lead frames. However, the effects of different precipitate types on the comprehensive properties of Cu–Co–Si alloys are not clear. Herein, several Cu–Co–Si alloys with various precipitates (CoSi, Co2Si, and Co) are designed based on phase diagrams calculation. The designed alloys are melted, cold‐rolled, and aged to test the corresponding hardness and electrical conductivity (EC). X‐ray diffraction and transmission electron microscopy are utilized to analyze the precipitates generated in those alloys. In the alloys with Co/Si ≤ 1, the excess Si atoms are not easy to precipitate from the copper lattice after CoSi precipitation, which seriously damages the EC. Co‐precipitation in alloys with Co/Si &gt; 2 is beneficial to improve EC without sacrificing hardness. According to thermodynamic calculation, precipitates in Cu‐1.62Co‐0.35Si (wt%) alloy with total elements between 1.5 and 2.0 wt% are all Co2Si and have the highest mass fraction in the equilibrium state. The different precipitates are highly dependent on the Co/Si atomic ratio and essential to Cu–Co–Si alloys’ mechanical and electrical performances.

High strength and high electrical conductivity in Cu–Fe alloys with nano and micro Fe particles

Simultaneous improvement of both the strength and electrical conductivity of Cu–Fe alloys (CFAs) through the conventional casting method is an extremely challenging task. In this study, an attempt was made to overcome this issue via preparing CFAs with ultrafine alloy powders embedded with nano Fe particles. Ultrafine CFA powders with various Fe contents ranging from 5 to 50 wt.% were synthesized by a novel rapid solidification route, namely, gas–water combined atomization (GWA) process. The alloy powders prepared via GWA were then processed by pressureless sintering, hot rolling, annealing, and cold rolling. The microstructure evolution, mechanical properties, and electrical conductivity of CFAs were comprehensively investigated. The average size of Cu grain and Fe particles in all sintered CFAs was smaller than 3 and 2 μm, respectively. The grains of sintered CFAs were obviously refined by the Fe particles, and the addition of Fe inhibited the formation of Cu twins. After rolling, the Fe particles elongated and became fibrous along the rolling direction. The degree of formation of fibrous Fe enhanced with the increase of Fe content. Cold-rolled CFAs with 5–50 wt% Fe exhibited the tensile strength of 560–1250 MPa and conductivity of 33–65% IACS, indicating that CFAs in this study achieved superior mechanical and electrical properties. The microstructure evolution and strengthening mechanisms of CFAs were described. These findings can provide new insights into the powder metallurgy manufacturing of high-performance CFAs.

Effect of boron on aging strengthened phase and properties of Cu–Cr–Zr alloy

The effect of trace B on the properties and microstructure of Cu–Cr–Zr alloy was investigated in this work. Aging precipitation phases in Cu matrix were analyzed by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). It was found that Cr is the main precipitation phase and its precipitation process is affected by B. Boron can increase the precipitation rate of the precipitation phase and promote the precipitation of the precipitation phase. After Cu–Cr–Zr alloy aged at 480 °C for 2 h, nanosized Cr particles were coherent with the Cu matrix and formed coherent G.P zones. In Cu–Cr–Zr alloy with 0.03wt% B addition, the aging precipitation process was accelerated, resulting in most of the aging precipitate being bcc Cr. Effect of trace B on hardness and electrical conductivity of Cu–Cr–Zr alloy was tested. It is indicated that B addition improves the hardness and electrical conductivity of the alloy and 0.03wt% B corresponds to the peak value of conductivity and hardness of Cu–Cr–Zr–B alloy.

High electrical conductivity of Cu wires cladded by Gr/Cu coating

Graphene/copper (Gr/Cu) coating-cladded copper (Cu) wires with high electrical conductivity and low surface roughness were successfully prepared from copper (II) sulfate pentahydrate (CuSO4·5H2O) containing graphene (Gr) ranging from 0 to 2.0 g/l by direct current electrodeposition. The Gr defect density, surface morphology, surface roughness and electrical conductivity of Gr/Cu coating-cladded copper wires were investigated. The results revealed that with increasing Gr concentration, the surface roughness and electrical conductivity of Gr/Cu coating-cladded copper wires were enhanced simultaneously. When the Gr concentration was 1.2 g/l, Gr/Cu coating-cladded copper wires possessed the lowest surface roughness of 4.241 μm and the highest electrical conductivity of 105.5% International Annealed Copper Standard. Compared with the counterpart without Gr, the surface roughness was reduced by 10.7%, and the electrical conductivity was increased by 5.4%. Models were developed to evaluate the surface roughness and electrical conductivity of Gr/Cu coating-cladded copper wires.

Enhancing strength and electrical conductivity of Cu–Cr composite wire by two-stage rotary swaging and aging treatments

The wide application of Cu–Cr composites is greatly limited by their trade-off of tensile strength and electrical conductivity . In this work, we employed an industrial method of rotary swaging (RS) and subsequent aging to improve the combination of strength and electrical conductivity of Cu-3.11Cr composite wire and reveal the microstructural evolutions during the processes. It is found that the matrix grains of Cu-3.11Cr have been significantly refined and elongated during the deformation and a fibrous structure has been formed. The average diameter of the grains has been reduced to about 3.9 μm after RS processing for an equivalent strain ∼3.5. Moreover, most of the initial micron sized Cr particles are elongated severely along axial direction which plays a role of fiber composite strengthening and reduces the scattering effect of electrons. Besides, lots of nano sized Cr particles re-precipitated in the matrix during the subsequent aging process. After the two-stage swaging and aging, the Cu-3.11Cr composite wire obtained a good comprehensive property with an ultimate tensile strength of 580 MPa and the electrical conductivity of 81.1% IACS (international annealed copper standard). We rationalized the high strength is attributed to dislocation, grain refinement, dispersion and precipitation as well as fiber-composite strengthening. The precipitation of Cr atoms from the Cu matrix during the aging treatment is vital for the enhancement of the electrical conductivity without loss of strength. These findings can provide some new insights in the mass production of the high performance Cu–Cr composites. • Cu–Cr composite wire with enhanced strength and electrical conductivity was prepared. • Two-stage rotary swaging and aging treatments was proposed. • High strength comes from dislocation, grain refinement, dispersion and precipitation.

Effect of ECAP processing on distribution of second phase particles, hardness and electrical conductivity of Cu−0.81Cr−0.07Zr alloy

The effect of equal-channel angular pressing (ECAP) processing at room temperature and 300 °C on the distribution of the second phase particles and its influence on hardness and electrical conductivity of the commercial Cu−0.81Cr−0.07Zr alloy were investigated. Microstructural characterization indicated that the area fraction of coarse Cr-rich particles decreased after ECAP processing. This reduction was attributed to the Cr dissolution induced by plastic deformation. The electrical conductivity of the alloy decreased by 12% after 4 ECAP passes at room temperature due to the increase of electrons scattering caused by higher Cr content in solid solution and higher density of defects in the matrix. These results were supported by the reduction of the Cu lattice parameter and by the exothermic reactions, during differential scanning calorimetry (DSC) analysis, observed only in the samples subjected to ECAP processing. Aging heat treatment after ECAP processing promoted an additional hardening effect and the complete recuperation of the electrical conductivity, caused by the re-precipitation of the partially dissolved particles. The better combination of hardness (191 HV) and electrical conductivity (83.5%(IACS)) was obtained after 4 ECAP passes at room temperature and subsequent aging at 380 °C for 1 h.

Effect of trace silicon addition on microstructure and properties of a Cu–0.26Cr–0.14Mg alloy

In this study, Cu-0.26Cr-0.14Mg and Cu-0.26Cr-0.14Mg-0.02Si (wt.%, nominal composition) alloys were used to study the effect of adding a small amount of Si on the comprehensive properties, microstructure by thermo-mechanical treatment. The properties results showed that the Cu–0.26Cr–0.14Mg–0.02Si alloy had a higher strength and electrical conductivity than Cu–0.26Cr–0.14Mg alloy. After 80% cold rolling and aging at 500 °C for 20 min, the hardness, tensile strength, and electrical conductivity of Cu–0.26Cr–0.14Mg–0.02Si alloy reached 162.8 HV, 523 MPa, and 82.0 %IACS, respectively. The microstructure results showed that Cr particles existed in the form of G.P zones in the early stage of aging, and there were three forms of existence in the later stage of aging: coffee-beans, Moiré fringes, and rod-like precipitates. The addition of Si greatly promoted the precipitation of the alloying elements, increased the fraction of the precipitates, refined the size of the precipitates, and thus improved the Orowan-Ashby strengthening and dislocation strengthening effects.

Effects of Fe content on microstructure and properties of Cu–Fe alloy

Cu–Fe alloys with different Fe contents were prepared by vacuum hot pressing. After hot rolling and aging treatment, the effects of Fe content on microstructure, mechanical properties and electrical conductivity of Cu–Fe alloys were studied. The results show that, when w(Fe)<60%, the dynamic recrystallization extent of both Cu phase and Fe phase increases. When w(Fe)≥60%, Cu phase is uniformly distributed into the Fe phase and the deformation of alloy is more uniform. With the increase of the Fe content, the tensile strength of Cu–5wt.%Fe alloy increases from 305 MPa to 736 MPa of Cu–70wt.%Fe alloy, the elongation decreases from 23% to 17% and the electrical conductivity decreases from 31%IACS to 19%IACS. These results provide a guidance for the composition and processing design of Cu–Fe alloys.