Electrical Conductivity Of Alloy Research Articles

Microstructure and properties of high strength, high conductivity Cu-2.5Fe-0.3Cr-0.3Mg-0.2Si-0.1Ca-0.1Zr alloy treated by multi-stage thermomechanical treatment

In the Cu-2.5Fe-0.3Cr-0.3 Mg-0.2Si-0.1Ca-0.1Zr alloy, a double-scale (micro and nano) FeCrSi second phase has been generated. The orientation relationship between nano-precipitates and the matrix is: (111)Cu//(202)FexCr(3-x)Si, 11¯0Cu//11¯1¯ FexCr(3-x)Si. The influence of the thermomechanical treatment process on the microstructure, mechanical properties and electrical conductivity of the alloy is explored. Results indicate that the final alloy has excellent properties. The hardness, yield strength, tensile strength and electrical conductivity of the final alloy are 204 HV, 635 MPa, 649 MPa and 63.57 %IACS, respectively. The calculations show that precipitation strengthening and dislocation strengthening have essential contributions to the strength of the final alloy. The former mainly comes from the strengthening effect of the FeCrSi nano-precipitates, and the latter is related to the multi-stage thermomechanical treatment process.

Influence of cerium and yttrium addition on strength and electrical conductivity of pure aluminum alloys

To develop pure aluminum alloys with high conductivity and strength, Al-0.2Ce and Al-0.2Ce-0.1Y alloys were prepared by rolling and annealing processes in this study. The effects of trace rare earth elements on the strength and electrical conductivity of the pure aluminum alloys were investigated. It is revealed that the addition of Ce and Y to pure aluminum can effectively enhance the strength and electrical conductivity of the alloys. In Al-0.2Ce, the addition of Ce can effectively refine the grain size of α-Al, with an average grain size of 90.68 μm in the as-cast state. The grain size of the alloy is further reduced to 87.55 μm by the simultaneous addition of Y. The synergistic addition of Ce and Y changes the properties of the alloy. The addition of Ce and Y also produces the Al11Ce3 and Al3Y second phases, which have coherent relationship with α-Al. The two-dimensional mismatch degree was calculated to be only 4.43% and 0.85%, respectively, which can provide a certain amount of nucleation substrate for α-Al in the incubation stage. The interfacial match between the L12 structure of Al3Y and α-Al was calculated using first-principles simulations. The results indicate that Al3Y has a strong bonding effect with α-Al. Nanoscale second phases at grain boundaries can be effective in reducing resistivity due to dislocation motion. Nanoscale second phases with better matching interfaces to the substrate have no positive effect on the scattering motion of electrons.

The wear resistance of Al–Si–Re alloys for electrical contact applications

We prepared aluminum–silicon–rare earth (Al–Si–Re) elements alloys for electrical contact applications. Three Si weight percentages (wt.%) — 10%, 20% and 30% — were used, and rare earth (Re) elements were kept at 0.35 wt.%. The spraying forming process was adopted, and high-pressure hot isostatic pressing (HIP) was conducted to obtain the bulk materials from the as-deposited billets. The electrical conductivity of alloys with 10% and 20% Si reached 40% International Annealed Copper Standard (IACS). The hardness of Al–Si alloys significantly increased with Si content and HIP processing times. The hardness of alloy with 30% Si reached [Formula: see text]90 HV. Meanwhile, HIP reduced weight loss in the wear resistance by reducing the microcracks and materials removal. The current study proposes an approach to manufacture Al–Si alloys with high electrical conductivity and high wear resistance.

Relationship and mechanism between double cold rolling-aging process, microstructure and properties of Cu–Ni–Si alloy prepared by two-phase zone continuous casting

Developing Cu–Ni–Si alloy with high strength and high electrical conductivity is a key issue in the electrical conductor industries. The C70250 copper alloy was prepared by two-phase zone continuous casting (TZCC) technology first, and then carried out by double cold rolling-aging process. The relationship between different double cold rolling-aging processes, microstructure, mechanical properties and electrical conductivity of the alloy was studied in detail, the mechanism was revealed. The results show that the C70250 copper alloy strip fabricated by TZCC technology can be subjected to large deformation double cold rolling-aging treatment. When the alloy is primary cold rolled by 97.5% reduction rate, primary aged at 400 °C for 30 min, second cold rolled by 60% reduction rate, second aged at 400 °C for 45 min, the tensile strength and electrical conductivity of the alloy can reach 879 MPa and 48.9% IACS respectively, owning excellent comprehensive properties. The Ni2Si phases inside C70250 copper alloy after primary aging effectively pin dislocations during the secondary cold rolling process, which forms high density dislocation entanglement, promotes the further precipitation of Ni2Si phase during the process of secondary aging, and finally produces a large number of fine, dispersed, multi-scale mixed and evenly distributed Ni2Si phases, the increase of alloy strength is mainly ascribed to dislocation and Orowan strengthening effect. Solute atoms inside the C70250 copper alloy get adequately precipitated after large deformation double cold rolling-aging treatment, the recrystallization is delayed, and the fibrous microstructure along the rolling direction is produced, the scattering effect of transverse grain boundaries and solute atoms on electrons is significantly reduced, which is helpful to improve the electrical conductivity of the C70250 copper alloy.

Hardness, quench sensitivity, and electrical conductivity of 7xxx Al alloys with high Zn concentrations

In this study, 7xxx (Al-Zn-Mg-Cu) alloys with high Zn concentrations were fabricated by increasing the Zn contents of 7085 Al alloys. The hardness, quench sensitivity, and electrical conductivity of the alloys and a 7085 Al alloy under peak-aged state were studied. The high Zn concentration alloys had higher η′ phase densities and lower quantities of Mg solid atoms than the 7085 Al alloy and thus exhibited higher hardness and electrical conductivity. The high Zn concentration alloys also exhibited slightly higher quench sensitivity than 7085 Al alloy, and the depth of the quenching layer of the alloy with 11.27 wt% Zn content reached 100 mm. This work confirmed that the novel 7xxx alloy with high Zn concentration showed balanced performance, exhibiting enhanced hardness and conductivity and reasonable quench sensitivity compared with the 7085 commercial Al alloy.

Development of Heat-Resistant Aluminum Alloys for Electrical Engineering Purposes Based on the Al – Fe – Si System

The effect of small additions of Mn, Ni, and Cr on a set of mechanical properties at room and elevated temperatures and electrical conductivity of alloys based on the Al – Fe – Si system is studied. It is shown that nickel increases electrical conductivity by 3% for alloys based on the Al – Fe – Si system, and chromium and manganese reduce it by 5 – 10%, which is connected with formation of a more alloyed solid solution. It is established that as a result of cold deformation treatment a dispersed structure forms within the alloy with an average excess phase size up to 0.7 μm. Excess phases of this size are effective recrystallization barriers, and therefore a cold-worked structure is retained in all alloys up to 300°C, which points to good thermal stability of the experimental alloys.

Effect of Zr on as-cast microstructure and properties of Cu-Cr alloy

Cu-15Cr and Cu-15Cr-0.24Zr alloys were prepared by means of vacuum medium frequency induction melting technology. The effects of Zr on the as-cast microstructure of Cu-15Cr alloy were studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Besides, the effect of Zr on the tensile strength and electrical conductivity of Cu-15Cr alloy was also studied after heavy drawing deformation. The experimental results show that the addition of Zr leads to the formation of thin CuZr compound phase. Moreover, the formation of eutectic Cr phase is inhibited, so that the content of eutectic Cr is much lower than that of Cu-15Cr alloy. The size of dendritic Cr is refined as well. Furthermore, the addition of Zr improves the tensile strength of the alloy, which has little effect on the electrical conductivity. It is observed that when the dependent variable η is 6.44, the tensile strength and electrical conductivity of the alloy can reach 1023 MPa and 72 %IACS respectively, which increases 117 MPa and reduces only by 2 %IACS.

Influence of various types of treatment on the structure, density, and electrical conductivity of deformed alloys of the Al–Mg system

A comparative investigation on the influence of AlZr4, AlZr10, and AlSc2 modifying master alloys, as well as magnetic-pulsed treatment (MPT) on density (in the liquid and solid states), electrical conductivity (in a solid state), and macrostructure of AMg5 and AMg6 alloys is performed. Mater melts are poured into special facilities providing cooling rates during the crystallization of ~102, ~103, and ~106C/s. Master alloys are introduced into the melts in an amount of 0.01% by the modifier element. It is shown that the modifying treatment of the melts by additives of nucleating master alloys promotes an increase in alloy densities in liquid and solid states. The electrical conductivity of alloys with additives of AlZr4 and AlZr10 master alloys lowers. The introduction of the AlSc2 master alloy increases in electrical conductivity of AMg5 and AMg6 alloys. This effect is established for the first time and requires additional investigations. It is established that, when compared with AlZr4 and AlZr10 master alloys, the AlSc2 master alloy prepared by crystallization in a water-cooled roll crystallizer most strongly affects the physical properties of alloys. It also provides the maximal macrograin refinement. MPT of alloys according to the axial effect scheme, similarly to the introduction of modifying master alloys, promotes an increase in the density of alloys in liquid and solid states. Electrical conductivity increases after MPT like after the addition of the AlSc2 master alloy into the melts. Alloy macrograin refining during MPT is comparable with the modification with the AlZr4 master alloy. Based on comparative investigations, it is concluded that MPT can be attributed to physical modification methods. It is proposed to use the determination procedures of density and electrical conductivity for the express evaluation of the modifying efficiency of studied effects.

INFLUENCE OF VARIOUS TREATMENT TYPES ON THE STRUCTURE, DENSITY, AND ELECTRICAL CONDUCTIVITY OF AL–MG SYSTEM WROUGHT ALLOYS

A comparative study was carried out to determine the effect of AlZr4, AlZr10 and AlSc2 modifying master-alloys and magnetic-pulse treatment (MPT) on the density (in liquid and solid state), electrical conductivity (in solid state) and macrostructure of AMg5 and AMg6 alloys. Molten master alloys were poured into special devices to ensure a cooling rate of ~10 2 , ~10 3 and ~10 6 °C/s during crystallization. Master alloys were introduced into the melts at the rate of 0.01% per modifier element. It is shown that melt modification with nucleating additives contributes to higher alloy density in liquid and solid states. The electrical conductivity of the alloys with AlZr4 and AlZr10 master alloys added is lower. The AlSc2 master alloy introduction causes an increase in the electrical conductivity of AMg5 and AMg6 alloys. This effect is observed for the first time and requires additional research. It is found that the AlSc2 master alloy obtained by crystallization in a water-cooled roller mold has the greatest influence on the physical properties of alloys in comparison with AlZr4 and AlZr10 master alloys. It also provides maximum macrograin refinement. Magnetic-pulse treatment (MPT) of melts following the axial scheme of impact contributes to higher density of alloys in liquid and solid states similar to the introduction of modifying master alloys. Electrical conductivity increases after MPT as with the AlSc2 master alloy added to melts. Alloy macrograin refinement at magnetic-pulse treatment is comparable with the addition of the AlZr4 modifying master alloy. The comparative studies allow for the conclusion that magnetic-pulse treatment can be attributed to physical modification methods. The methods of density and electrical conductivity determination can be used for express evaluation of the studied effects for their modifying effectiveness.

Effects of Fe and P Additions on Microstructures and Properties of Cu-Cr-Zr Resistance Spot Welding Electrode Alloy

In this paper, the effects of contents of Fe and P on the microstructures and properties of Cu-Cr-Zr resistance spot welding electrode alloys have been studied by means of electrical conductivity and hardness measurements and optical microscopy. By the addition of 2.5%Fe and 0.03P%, after being aged for 6h, the Cu-Cr-Zr-Fe-P alloy has the highest hardness of 125HV. At this time, the electrical conductivity of alloy is 60%IACS. The addition of 0.1%Zn contributes very little to hardness and electrical changes.

Effect of Ag Addition on the Microstructure and Properties of Cu-5Cr Base Alloys

Small amount of Ag was added to high conductivity Cu-5%Cr alloy in order to increase the strength without sacrificing the conductivity. The typical microstructure of thermo-mechanically processed specimen mainly consists of Cu matrix and relatively large Cr phase. Although this typical microstructure was not changed with varied process variables, both the micro-hardness and conductivity were significantly affected by them. The electrical conductivity of alloy was slightly decreased by the Ag addition, but the micro-hardness could be enhanced by it. TEM analyses indicated that very fine Cr precipitates were formed in addition to the relatively large Cr phase in the Cu matrix. It is suggested that the properties of Cu-5Cr-xAg alloys can be optimized by carefully controlling the precipitation of the fine precipitates.

Heat-resistant Al–0.2Sc–0.04Zr electrical conductor

The combined effects of ageing and cold-rolling on the tensile and conductive properties of Al–0.2Sc–0.04Zr alloys were investigated. Both the tensile strength and electrical conductivity of alloys after cold-rolling+ageing or pre-ageing+cold-rolling+ageing treatments are apparently better than that of the only aged alloy; furthermore, the improvements on the properties made by pre-ageing+cold-rolling+ageing are slightly greater than that by cold-rolling+ageing. TEM observations indicate that the increase of strength should be associated with the formation of finer Al3(ScZr) precipitates and substructure with boundaries pinned by nano-sized precipitates while the improvement of conductivity should be caused by the closure of microvoids. As an electrical conductor, the highest working temperature of Al–0.2Sc–0.04Zr with the best strength and conductivity can be as high as 345°C. It strongly suggests that the Al–Sc–Zr alloy has a great application prospect in heat resistant conductor fields.

Effect of Ag Addition on the Microstructure and Mechanical Properties of High Conductivity Cu-1Cr-Mg-P Alloy

High strength high conductivity Cu-1%Cr-Mg-P alloy was selected as a base composition and Ag was added to the alloy in order to further increase the strength without sacrificing the conductivity. SEM and TEM analyses indicated that very fine MgP and Ag(Mg) precipitates were formed in addition to relatively large Cr phase in the Cu matrix. Significantly high strength could be obtained through the special cold rolling at an extremely low temperature using liquid nitrogen. The electrical conductivity of alloy was slightly decreased by the Ag addition, but the tensile strength could be further enhanced by it.

Dipole scattering in highly polar semiconductor alloys

The wide gap polar semiconductors III-V nitrides, II-VI oxides, and ferroelectrics exhibit large spontaneous and piezoelectric polarization due to their nonsymmetric crystal structures. Electrical conductivity in alloys of such crystals is degraded by scattering from the varying polarization coupled to alloy disorder. We have modeled this effect by dipole scattering. We have calculated dipole scattering limited mobility in the relaxation time approximation of the Boltzmann equation. The results are applied to AlxGa1−xN layers coherently strained on GaN. For a typical carrier concentration of 1018(cm−3) in Al0.3Ga0.7N, dipole scattering limited mobilities are 2535 and 3420(cm2∕Vs) at 300 and 77K, respectively. Applying our results to ferroelectric alloys, we reach the interesting conclusion that dipole scattering in such alloys will lead to extremely low mobilities (1–10cm2∕Vs), since it degrades as the square of average dipole moment. This leads us to suggest that digital alloy growth might be necessary to achieve high conductivities in highly polar wide gap alloy semiconductors and ferroelectrics for device applications.

Thermal and electrical properties of Czochralski grown GeSi single crystals

The thermoelectric parameters, thermal conductivity, electrical conductivity and Seebeck coefficient of high quality single crystals of Ge 1− x Si x alloys in various composition of 0.8< x<1, were investigated in the temperature range 300–1000 K for application to a high performance thermoelectric device. Single crystals of the alloys of heavily impurity-doped were grown by the Czochralski technique. The thermal conductivity was mainly controlled by phonon scattering, showing a minimum at x=0.5–0.6. The electrical conductivity of alloys was well controlled to be almost constant with a high magnitude by the suitable doping level. The Seebeck coefficient was 300–400 μV/K at 600°C in the impurity-doped GeSi alloys. The dependence of the Seebeck coefficient on the electrical conductivity was revealed. The dimensionless figure of merit of 0.65 was evaluated in the impurity-doped single crystals of GeSi alloys.

Quaternary Cu-0.7%Cr-0.3%Fe-X alloys

This research is part of a project whose scope was to investigate the engineering properties of new non-commercial alloy formulations based on the Cu rich corner of the Cu-Fe-Cr ternary system with the primary aim of exploring the development of a new cost-effective high-strength, high-conductivity copper alloy. The aim of the present work was to increase the electrical conductivity and strength of the Cu-0.7wt%Cr-0.3wt%Fe alloy through selective minor additions (≤0.15 wt%) of elements expected to promote precipitation of dissolved Fe: Ti, B, P, Ni & Y. Such quaternary alloys with reduced Fe in solid solution would be expected to have properties equivalent to or better than those of the Cu-1%Cr reference alloy (Alloy Z). The investigation showed that none of the trace element additions significantly improved the size of the age hardening response or the peak aged electrical conductivity of Alloy A, although further work is required on the influence of Ti. Additions of P and B were detrimental. Other trace additions had little or no effect apart from causing some slight changes to the precipitation kinetics. The mechanical properties of the Cu-0.7%Cr-0.3%Fe alloy made with less expensive high carbon ferrochrome were found to be inferior to those of the equivalent alloy made with low carbon ferrochrome.

Theory of the conductivity of ordered alloys

A theory of the electrical conductivity of alloys going beyond the coherent potential approximation and taking into account statistical correlations in the scattering of the electrons by the atoms is developed. The two-particle Green's functions for the electrons is calculated with allowance for scattering by pairs of atoms (the zeroth approximation corresponds to the coherent potential approximation), the correlations being described by means of the parameters of the short-and long-range order. It is shown that the change in the electron spectrum on ordering leads to a significant change of the alloy conductivity.

COPPER ALLOY No. C18700

Abstract Copper Alloy No. C18700 is a copper-base alloy containing lead (nominally 1.0%). The lead is added to impact free-cutting properties to the metal. Although the lead lowers the electrical conductivity of Alloy No. C18700 slightly below that of tough-pitch copper, it still has high electrical conductivity well within the limits needed for most current-carrying requirements. Typical uses comprise electrical motor and switch parts, electrical connectors and screw-machine parts requiring high conductivity. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Cu-441. Producer or source: Copper and copper alloy mills.

Address of the President Sir Alan Hodgkin at the Anniversary Meeting, 30 November 1972

The Copley Medal is awarded to Sir Nevill Mott, F. R. S. At an early stage in his career Mott had already established a reputation as a pioneer in the field of atomic collision theory based on the new wave mechanics. He was the first to show that Rutherford’s scattering law remains exactly valid when this mechanics is employed, and to point out the importance of symmetry in scattering problems. He was also the first to apply Dirac’s relativistic theory to these problems and showed that under certain conditions electrons may be polarized by double scattering. Even as early as 1932 he realized the importance of conservation laws in limiting reaction cross sections. All of this work was characterized by a remarkable degree of originality and physical insight combined with mathematical skill. When, at the age of 27, he became professor of theoretical physics at Bristol, he abandoned the study of atomic collisions to work on the theory of metals and alloys, in order that he might relate his work more closely to that of a new group of experimenters. Within a few years he was recognized as one of the leading inter­national authorities in this field, to which he contributed a number of important papers on electronic bands in metals and on the electrical conductivity of alloys and its temperature coefficient.

Address of the President Sir Alan Hodgkin at the Anniversary Meeting, 30 November 1972

The Copley Medal is awarded to Sir Nevill Mott, F.R.S. At an early stage in his career Mott had already established a reputation as a pioneer in the field of atomic collision theory based on the new wave mechanics. He was the first to show that Rutherford’s scattering law remains exactly valid when this mechanics is employed, and to point out the importance of symmetry in scattering problems. He was also the first to apply Dirac’s relativistic theory to these problems and showed that under certain conditions electrons may be polarized by double scattering. Even as early as 1932 he realized the importance of conservation laws in limiting reaction cross sections. All of this work was charac­terized by a remarkable degree of originality and physical insight combined with mathematical skill. When, at the age of 27, he became professor of theoretical physics at Bristol, he abandoned the study of atomic collisions to work on the theory of metals and alloys, in order that he might relate his work more closely to that of a new group of experimenters. Within a few years he was recognized as one of the leading inter­national authorities in this field, to which he contributed a number of important papers on electronic bands in metals and on the electrical conductivity of alloys and its temperature coefficient.