Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-...Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-speed rail contact wires,electronic component connectors,and other devices.Overcoming the contradiction between low alloying and high performance is an important challenge in the development of solid solution-strengthened copper alloys.Taking the typical solid solution-strengthened alloy Cu-4Zn-1Sn as the research object,we proposed using the element In to replace Zn and Sn to achieve low alloying in this work.Two new alloys,Cu-1.5Zn-1Sn-0.4In and Cu-1.5Zn-0.9Sn-0.6In,were designed and prepared.The total weight percentage content of alloying elements decreased by 43%and 41%,respectively,while the product of ultimate tensile strength(UTS)and electrical conductivity(EC)of the annealed state increased by 14%and 15%.After cold rolling with a 90%reduction,the UTS of the two new alloys reached 576 and 627MPa,respectively,the EC was 44.9%IACS and 42.0%IACS,and the product of UTS and EC(UTS×EC)was 97%and 99%higher than that of the annealed state alloy.The dislocations proliferated greatly in cold-rolled alloys,and the strengthening effects of dislocations reached 332 and 356 MPa,respectively,which is the main reason for the considerable improvement in mechanical properties.展开更多
In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduce...In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduced for welding.T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser welding.The morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap joints.The microstructure characteristics of the weld zone were observed and compared by optical microscope.The results show that the addition of laser beam swing can eliminate the internal pores of the weld.With the increase of the swing width,the weld depth decreases,and the weld width increases first and then decreases.The influence of welding speed on the weld cross section morphology is similar to that of swing width.With the increase of welding speed,the weld width increases first and then decreases,while the weld depth decreases all the time.This is because that the red laser is used as the main heat source to melt the base metals,with the increase of red laser power,the weld depth increases.As an auxiliary laser source,blue laser reduces the total energy consumption,consequently,the effective heat input increases and the spatter is restrained effectively.As a result,the increase of red laser power has an enhancement effect on the weld width and weld depth.When the swing width is 1.2 mm,the red laser power is 550 W,the blue laser power is 500 W,and the welding speed is 35 mm/s,the weld forming is the best.The lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue laser.The effect rules of laser beam swing on the weld formation were obtained,which improved the quality of the joints.展开更多
Laser-induced breakdown spectroscopy(LIBS)is a capable technique for elementary analysis,while LIBS quantitation is still under development.In quantitation,precise laser focusing plays an important role because it ens...Laser-induced breakdown spectroscopy(LIBS)is a capable technique for elementary analysis,while LIBS quantitation is still under development.In quantitation,precise laser focusing plays an important role because it ensures the distance between the laser and samples.In the present work,we employed spectral intensity as a direct way to assist laser focusing in LIBS quantitation for copper alloys.It is found that both the air emission and the copper line could be used to determine the position of the sample surface by referencing the intensity maximum.Nevertheless,the fine quantitation was only realized at the position where the air emission(e.g.O(I)777.4 nm)reached intensity maximum,and also in this way,a repeatable quantitation was successfully achieved even after 120 days.The results suggested that the LIBS quantitation was highly dependent on the focusing position of the laser,and spectra-assisted focusing could be a simple way to find the identical condition for different samples’detection.In the future,this method might be applicable in field measurements for LIBS analysis of solids.展开更多
China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed...China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed the non-argent Lanthanum-tellurium-copper alloy as a substitute for industry argent-copper. In our research, we were able to successfully apply rare earth lanthanum to copper alloy. The defects as porosity, inclusion, etc. originating from nonvacuum melting processing were controlled. Fine grain was obtained. Meanwhile, the comprehensive properties of the copper alloy, such as strength, conductivity and thermal conductivity were improved. The research results in increasing conductivity and thermal conductivity by 5% and 15%, respectively, while the tensile strength is increased by 6% higher than Ag-Cu alloy. The anti-electric corrosion property is good, and there is no argent-cadmium steam population originating from the electric arc effect. The addition of lanthanum further reduces the content of oxygen and hydrogen. The optimum quantity of the addition of RE lanthanum in the copper alloy is 0.010% - 0.020% .展开更多
The electrodeposition of A1 and A1-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing A1C13-EtaNHC1 was studied. The electrochemical behavior of the electrolyte and the ...The electrodeposition of A1 and A1-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing A1C13-EtaNHC1 was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry (CV), and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). A1 of 70μm in thickness and an A1-Cu alloy of 30μm in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the A1 deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be (30±5) and (29±5) nm, respectively, for A1 and A1-Cu alloys. Potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopic (EIS) measurements showed that Al-Cu alloys are more corrosion resistant than Al.展开更多
Al2O3 dispersion copper alloy powder was prepared by intemal oxidation, and three consolidation methods--high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)--were used to prepare Al2O3 disp...Al2O3 dispersion copper alloy powder was prepared by intemal oxidation, and three consolidation methods--high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)--were used to prepare Al2O3 dispersion-strengthened copper (Cu-Al2O3) alloys. The microstructures and properties of these alloys were investigated and compared. The results show that the alloys prepared by the HP and HE methods exhibited the coarsest and finest grain sizes, respectively. The alloy prepared by the HVC method exhibited the lowest relative density (98.3% vs. 99.5% for HP and 100% for HE), which resulted in the lowest electrical conductivity (81% IACS vs. 86% IACS for HP and 87% IACS for HE). However, this alloy also exhibited the highest hardness (77 HRB vs. 69 HRB for HP and 70 HRB for HE), the highest compressive strength (443 MPa vs. 386 MPa for I/P and 378 MPa for HE), and the best hardness retention among the investigated alloys. The results illustrate that the alloy prepared by the HVC method exhibits high softening temperature and good mechanical properties at high temperatures, which imply long service life when used as spot-welding electrodes.展开更多
The grain boundary structure of Cu alloy was observed and the characteristic of the boundaries was studied,including 70∶30 cupronickel and 70∶30 brass. The results show that in the case of the 70∶30 cupronickel thi...The grain boundary structure of Cu alloy was observed and the characteristic of the boundaries was studied,including 70∶30 cupronickel and 70∶30 brass. The results show that in the case of the 70∶30 cupronickel thin platelets with nickel and iron enrichment in it precipitate intergranular so that the alloy was sensitive to seawater corrosion. In the case of 70∶30 brass the situation of grain boundary segregation of different inclusions made the corrosion resistance of the alloy even worse. All of those were discovered through the corrosion behavior of the two different copper alloys served in various environments. The experimental methods used here were, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive of X ray(EDX). The intergranular corrosion morphologies of those copper alloys served in engineering or exposed to seawater for a long term were given.展开更多
An actively water-cooled limiter has been designed for the long pulse operation of an HT-7 device, by adopting an integrated structure-doped graphite and a copper alloy heat sink with a super carbon sheet serving as a...An actively water-cooled limiter has been designed for the long pulse operation of an HT-7 device, by adopting an integrated structure-doped graphite and a copper alloy heat sink with a super carbon sheet serving as a compliant layer between them. The behaviors of the integrated structure were evaluated in an electron beam facility under different heat loads and cooling conditions. The surface temperature and bulk temperature distribution were carefully measured by optical pyrometers and thermocouples under a steady state heat flux of 1 to 5 MW/m^2 and a water flow rate of 3 m^3/h, 4.5 m^3/h and 6 m^3/h, respectively. It was found that the surface temperature increased rapidly with the heat flux rising, but decreased only slightly with the water flow rate rising. The surface temperature reached approximately 1200℃ at 5 MW/m^2 of heat flux and 6 m^3/h of water flow. The primary experimental results indicate that the integrated design meets the requirements for the heat expelling capacity of the HT-7 device. A set of numerical simulations was also completed, whose outcome was in good accord with the experimental results.展开更多
Rapidly solidified aging is an effective way to refine the microstructure of Cu-Cr-Sn-Zn lead frame alloy and enhance its hardness. The artificial neural network methodology(ANN) along with genetic algorithms were use...Rapidly solidified aging is an effective way to refine the microstructure of Cu-Cr-Sn-Zn lead frame alloy and enhance its hardness. The artificial neural network methodology(ANN) along with genetic algorithms were used for data analysis and optimization. In this paper the input parameters of the artificial neural network (ANN) are the aging temperature and aging time. The outputs of the ANN model are the hardness and conductivity properties. Some explanations of these predicted results from the microstructure and precipitation-hardening viewpoint are given. After the ANN model is trained successfully, genetic algorithms(GAs) are applied for optimizing the aging processes parameters.展开更多
Copper alloys suitable for laser cladding on cast iron are selected trom rune types of conventional powders. There are a poor spreading ability and porosity of copper alloy over the surface of castiron. Copper alloy s...Copper alloys suitable for laser cladding on cast iron are selected trom rune types of conventional powders. There are a poor spreading ability and porosity of copper alloy over the surface of castiron. Copper alloy surface is easily oxidized in atmosphere. These shortages have been overcome by ad- ding deoxidizers of Si and H_3BO_3. Laser parameters, stress and coefficient of friction have been ex- amined, and the larger smooth surface of Cu/cast iron for friction by laser cladding has been made for the application of the guide shoes of machine.展开更多
The experimental investigation of different transition metals was carried out in the diffusion bonding joints of Cu alloys (CuAlBe) to stainless steel (1Cr18Ni9Ti). The microstructure of the joint was analyzed with mi...The experimental investigation of different transition metals was carried out in the diffusion bonding joints of Cu alloys (CuAlBe) to stainless steel (1Cr18Ni9Ti). The microstructure of the joint was analyzed with microscopic examination, SEM, EPMA and X ray diffraction. Following conclusions have been drawn: (1) The joint strength with the Ni interlayer was higher than that with Cu interlayer when the welding parameters were same;(2)When Ni interlayer was thinner,Al could interact with Ni and Fe,and the intermetallic compounds,such as Fe 3Al etc,were formed in the interface,which decreased the strength of the joints;(3)When the bonding temperature was higher,because of the diffusion of Cu in Ni being faster than Ni in Cu,a Kirkendall effect was produced,which also decreased the strength of the joints.展开更多
The cleaning process of removing oxides on the surface of copper alloy sheetswas investigated systematically. Through optimizing, a perfect process was selected that is fit forremoving oxides on the surface. By acid p...The cleaning process of removing oxides on the surface of copper alloy sheetswas investigated systematically. Through optimizing, a perfect process was selected that is fit forremoving oxides on the surface. By acid pickling, all kinds of copper oxides are removedcompletely, furthermore, no poisonous gases are given out and a smooth and clean surface of copperalloys is obtained. At present, the process is applied successfully in the copper-processingindustry.展开更多
Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-cond...Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.展开更多
Electroreduction of carbon dioxide(CO_(2)) into value-added chemicals offers an entrancing approach to main-taining the global carbon cycle and eliminating environmental threats.A key obstacle to achieving long-term a...Electroreduction of carbon dioxide(CO_(2)) into value-added chemicals offers an entrancing approach to main-taining the global carbon cycle and eliminating environmental threats.A key obstacle to achieving long-term and large-scale implementation of electrochemical CO_(2) reduction technology is the lack of active and selective cat-alysts.Copper(Cu)is one of the few candidates that can facilitate C–C coupling to obtain high-energy oxygenates and hydrocarbons beyond carbon monoxide(CO),but it suffers from poor selectivity for products of interest and high overpotentials.Alloying is an effective way to break the linear scaling relations and uniquely manipulate the reactivity and selectivity,which is hard to achieve by using monometallic compositions alone.By alloying Cu with other metals,one could change the catalytic properties of the catalyst by tuning the local electronic structure and modulating the adsorption strength of the reaction intermediates,thus improving the catalytic activity and selectivity.In this review,we focus on the recently developed Cu-based alloy catalysts(including conventional alloys,high-entropy alloys and single-atom alloys)that have been applied in electrocatalytic CO_(2) reduction(ECR).Theoretical calculations and experimental advances in understanding the key rate-limiting and selectivity-determining steps in those alloys are summarized,with a particular focus on identifying binding energy de-scriptors and the dynamic product formation mechanisms.In addition,we outline the opportunities and chal-lenges in the fundamental understanding of ECR by recommending advanced in-situ characterization techniques and standardized electrochemical methods and offer atomic-level design principles for steering the reaction pathways to the desired products.展开更多
Cu-Ni-Al alloys at different concentrations were obtained using a high frequency induction melting unit, keeping a balance in the nominal compositions. Light alloys are important to be used in industrial applications....Cu-Ni-Al alloys at different concentrations were obtained using a high frequency induction melting unit, keeping a balance in the nominal compositions. Light alloys are important to be used in industrial applications. Aluminum additions result in a positive hardness increment of the ternary alloys in comparison with the binary Cu-Ni alloys. Generalized wear mechanisms of the alloys with low aluminum content are basically type abrasive, while samples with 5 and 10 at.% Al present an oxidative-adhesive wear mechanism. Wear results have indicated that aluminum addition affects positively the wear resistance, mainly in samples with high aluminum content product of the creation during the test of different oxides corresponding to the elements present in the alloys.展开更多
Microstructures have profound effects on the hardness and strength of Cu-Cr alloys. The microstructures of a Cu-Cr alloy cast in a water-cooled copper mold were studied in the present work. The scanning electron micro...Microstructures have profound effects on the hardness and strength of Cu-Cr alloys. The microstructures of a Cu-Cr alloy cast in a water-cooled copper mold were studied in the present work. The scanning electron microscopy (SEM) results show that there are the copper matrix saturated with chromium, spherical precipitates of chromium separated from liquid phase during cooling before the initiation of so- lidification, and a eutectic phase in grain boundary areas. To investigate the effect of age-hardening treatment on the microstructures and properties of the material, some samples were subsequently age-hardened in a salt bath and investigated by transmission electron microscopy (TEM). The results show that coherent precipitates with the diameter of 11 nm are detectable in the samples before and after the age-hardening stage. Of course, the volume fraction of coherent precipitates is higher after the aging process.展开更多
The compression tests were carried out by Gleeble-1500 thermo-mechanical simulator with samples of semi-solid ZCuSnl0 alloy prepared by strain-induced melt activation (SIMA) process. The original microstruc- ture an...The compression tests were carried out by Gleeble-1500 thermo-mechanical simulator with samples of semi-solid ZCuSnl0 alloy prepared by strain-induced melt activation (SIMA) process. The original microstruc- ture and the deformation temperature of semi-solid ZCuSnl0 alloy are different. The strain is 0.2, and the strain rate is 1 s-1 for the compression test. The results show that when the semi-solid ZCuSnl0 alloy was pre- pared by SIMA process, the liquid fraction of semi-solid microstructure increases, and the solid grain is smaller, more uniform and more inclined to be round as the roiling pre-deformation increasing. The results also indicate that the deformation resistance of ZCuSnl0 alloy in semi-solid state decreases with the deformation temperature increas- ing or the solid fraction of original microstructure de- creasing. The stress-strain curves of the isothermal compression can be divided into quasi-elastic deformation stage and plastic deformation stage, and there are three deformation zones in the samples after isothermal com- pression, namely the difficult deformation zone, the large deformation zone and the free deformation zone. In the three deformation zones, the main deformation mechanism is flow of liquid incorporating solid particles (FLS) mechanism, plastic deformation of solid particles (PDS) mechanism and liquid flow (LF) combining with FLS mechanism, respectively.展开更多
The microstructure and nano-hardness of the pure copper and oxide dispersion-strengthened(ODS) copper alloy subjected to 1.4 Me V Au ions irradiation at room temperature were investigated. After irradiation, disloca...The microstructure and nano-hardness of the pure copper and oxide dispersion-strengthened(ODS) copper alloy subjected to 1.4 Me V Au ions irradiation at room temperature were investigated. After irradiation, dislocation-loops form in both materials, while voids can only be generated in the pure copper. Compared with the irradiated pure copper, larger average diameter and lower number density of irradiation-induced dislocation-loops were detected in the ODS copper alloy, revealing that high-density dislocation and large volume of Al2O3 particles existing in the ODS copper alloy can act as effective sinks for the irradiation-induced defects. It was also detected that irradiation hardening in the ODS copper alloy is lower than that in the pure copper. The microstructure and nano-hardness results reveal that the ODS copper alloy has a better irradiation tolerance than the pure copper. In addition, the average diameter of the Al2O3 particles in the ODS copper alloy decreases after irradiation, because the Al–O chemical bonds are decomposed and the atoms are redistributed in the matrix during the irradiation process. This work reveals that the irradiation tolerance of the copper can be effectively enhanced by adding nano-sized Al2O3 particles into the matrix.展开更多
By means of Precipitation hardening, a cast copper alloy with high strength and heatresistance named Cu-6Ti-Cr-Al has been developed. This alloy has good castability. After water quenching at 860℃ for 1 h and aging a...By means of Precipitation hardening, a cast copper alloy with high strength and heatresistance named Cu-6Ti-Cr-Al has been developed. This alloy has good castability. After water quenching at 860℃ for 1 h and aging at 450℃ for 4 h, the tensile strength, σ_b, is greater than 890MPa and the compressive strength, σ_(bc), reaches 1300MPa, while the ratio of compression, ε_c, is maintained at 20%. When the environmental temperature is raised to 450℃, the mechanical properties do not show any appreciable loss. These copper alloy castings have been used on the roll sleeves of rubber formers and the journal bearings of sheet mills. The results have shown that the service life of these parts is much longer than that of aluminium bronze and 904alloy castings. In the present work, the microstructure, mechanical properties and strengthening mechanism were investigated.展开更多
Choosing two different elements of rare earth, the absorptivity of them on copper and its alloys were researched from the category of rare earth, melting point, adding methods, casting temperature, time of heat preser...Choosing two different elements of rare earth, the absorptivity of them on copper and its alloys were researched from the category of rare earth, melting point, adding methods, casting temperature, time of heat preservation, quantity of rare earth additives etc. The laws of affecting the absorptivity are found through the research. The distributing of rare earth, existent state and the formed compounds on copper and its alloys were observed in the casting state. The absorptivities of rare earth on copper and its alloys were analyzed.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3803101)the National Natural Science Foundation of China(Nos.52022011,51974028,and 52090041)+1 种基金the Xiaomi Young Scholars ProgramChina National Postdoctoral Program for Innovative Talents(No.BX20230042)。
文摘Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-speed rail contact wires,electronic component connectors,and other devices.Overcoming the contradiction between low alloying and high performance is an important challenge in the development of solid solution-strengthened copper alloys.Taking the typical solid solution-strengthened alloy Cu-4Zn-1Sn as the research object,we proposed using the element In to replace Zn and Sn to achieve low alloying in this work.Two new alloys,Cu-1.5Zn-1Sn-0.4In and Cu-1.5Zn-0.9Sn-0.6In,were designed and prepared.The total weight percentage content of alloying elements decreased by 43%and 41%,respectively,while the product of ultimate tensile strength(UTS)and electrical conductivity(EC)of the annealed state increased by 14%and 15%.After cold rolling with a 90%reduction,the UTS of the two new alloys reached 576 and 627MPa,respectively,the EC was 44.9%IACS and 42.0%IACS,and the product of UTS and EC(UTS×EC)was 97%and 99%higher than that of the annealed state alloy.The dislocations proliferated greatly in cold-rolled alloys,and the strengthening effects of dislocations reached 332 and 356 MPa,respectively,which is the main reason for the considerable improvement in mechanical properties.
基金supported by Guangdong Science and Technology Plan Project(Grant No.20170902,No.20180902)Yangjiang Science and Technology Plan Project(Grant No.SDZX2020063)+1 种基金Shenzhen Key Projects of Innovation and Entrepreneurship Plan Technology(JSGG20210420091802007)Yunfu 2023 Science and Technology Plan Project(S2023020201).
文摘In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduced for welding.T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser welding.The morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap joints.The microstructure characteristics of the weld zone were observed and compared by optical microscope.The results show that the addition of laser beam swing can eliminate the internal pores of the weld.With the increase of the swing width,the weld depth decreases,and the weld width increases first and then decreases.The influence of welding speed on the weld cross section morphology is similar to that of swing width.With the increase of welding speed,the weld width increases first and then decreases,while the weld depth decreases all the time.This is because that the red laser is used as the main heat source to melt the base metals,with the increase of red laser power,the weld depth increases.As an auxiliary laser source,blue laser reduces the total energy consumption,consequently,the effective heat input increases and the spatter is restrained effectively.As a result,the increase of red laser power has an enhancement effect on the weld width and weld depth.When the swing width is 1.2 mm,the red laser power is 550 W,the blue laser power is 500 W,and the welding speed is 35 mm/s,the weld forming is the best.The lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue laser.The effect rules of laser beam swing on the weld formation were obtained,which improved the quality of the joints.
基金financially supported by the Provincial Key Research and Development Program of Shandong,China(No.2019GHZ010)the Natural Science Foundation of Shandong Province(No.ZR2020MF123)+1 种基金National Natural Science Foundation of China(Nos.61975190 and12174359)the Fundamental Research Funds for the Central Universities(No.202161002)。
文摘Laser-induced breakdown spectroscopy(LIBS)is a capable technique for elementary analysis,while LIBS quantitation is still under development.In quantitation,precise laser focusing plays an important role because it ensures the distance between the laser and samples.In the present work,we employed spectral intensity as a direct way to assist laser focusing in LIBS quantitation for copper alloys.It is found that both the air emission and the copper line could be used to determine the position of the sample surface by referencing the intensity maximum.Nevertheless,the fine quantitation was only realized at the position where the air emission(e.g.O(I)777.4 nm)reached intensity maximum,and also in this way,a repeatable quantitation was successfully achieved even after 120 days.The results suggested that the LIBS quantitation was highly dependent on the focusing position of the laser,and spectra-assisted focusing could be a simple way to find the identical condition for different samples’detection.In the future,this method might be applicable in field measurements for LIBS analysis of solids.
基金Project supported by the National Scientific and Technological Achievements Spread Project (2004EC00299)Science and Technology Type Middle and Small Business Technique Invention Fund (04C26225121390)
文摘China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed the non-argent Lanthanum-tellurium-copper alloy as a substitute for industry argent-copper. In our research, we were able to successfully apply rare earth lanthanum to copper alloy. The defects as porosity, inclusion, etc. originating from nonvacuum melting processing were controlled. Fine grain was obtained. Meanwhile, the comprehensive properties of the copper alloy, such as strength, conductivity and thermal conductivity were improved. The research results in increasing conductivity and thermal conductivity by 5% and 15%, respectively, while the tensile strength is increased by 6% higher than Ag-Cu alloy. The anti-electric corrosion property is good, and there is no argent-cadmium steam population originating from the electric arc effect. The addition of lanthanum further reduces the content of oxygen and hydrogen. The optimum quantity of the addition of RE lanthanum in the copper alloy is 0.010% - 0.020% .
基金financial support from ISRO under RESPOND scheme(No.ISRO/RES/3/580/2007-08)
文摘The electrodeposition of A1 and A1-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing A1C13-EtaNHC1 was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry (CV), and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). A1 of 70μm in thickness and an A1-Cu alloy of 30μm in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the A1 deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be (30±5) and (29±5) nm, respectively, for A1 and A1-Cu alloys. Potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopic (EIS) measurements showed that Al-Cu alloys are more corrosion resistant than Al.
基金financially supported by Guangdong Provincial Industrial High-tech Project (No. 2015A010105020)Guangzhou Science & Technology New Star of Pearl River Project (No. 2012J2200096)+3 种基金the Open Research Fund of State Key Laboratory of Powder Metallurgy of Central South UniversityGuangdong Provincial Innovation Ability Construction Project (No. 2016B070701024)Guangzhou Innovation Platform Construction and Sharing Project (No. 201509010003)Guangdong Provincial Science & Technology Basic Condition Construction Field Project (No. 2014B030301012)
文摘Al2O3 dispersion copper alloy powder was prepared by intemal oxidation, and three consolidation methods--high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)--were used to prepare Al2O3 dispersion-strengthened copper (Cu-Al2O3) alloys. The microstructures and properties of these alloys were investigated and compared. The results show that the alloys prepared by the HP and HE methods exhibited the coarsest and finest grain sizes, respectively. The alloy prepared by the HVC method exhibited the lowest relative density (98.3% vs. 99.5% for HP and 100% for HE), which resulted in the lowest electrical conductivity (81% IACS vs. 86% IACS for HP and 87% IACS for HE). However, this alloy also exhibited the highest hardness (77 HRB vs. 69 HRB for HP and 70 HRB for HE), the highest compressive strength (443 MPa vs. 386 MPa for I/P and 378 MPa for HE), and the best hardness retention among the investigated alloys. The results illustrate that the alloy prepared by the HVC method exhibits high softening temperature and good mechanical properties at high temperatures, which imply long service life when used as spot-welding electrodes.
文摘The grain boundary structure of Cu alloy was observed and the characteristic of the boundaries was studied,including 70∶30 cupronickel and 70∶30 brass. The results show that in the case of the 70∶30 cupronickel thin platelets with nickel and iron enrichment in it precipitate intergranular so that the alloy was sensitive to seawater corrosion. In the case of 70∶30 brass the situation of grain boundary segregation of different inclusions made the corrosion resistance of the alloy even worse. All of those were discovered through the corrosion behavior of the two different copper alloys served in various environments. The experimental methods used here were, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive of X ray(EDX). The intergranular corrosion morphologies of those copper alloys served in engineering or exposed to seawater for a long term were given.
基金The project partially supported by National Natural Science Foundation of China (No. 10275069)
文摘An actively water-cooled limiter has been designed for the long pulse operation of an HT-7 device, by adopting an integrated structure-doped graphite and a copper alloy heat sink with a super carbon sheet serving as a compliant layer between them. The behaviors of the integrated structure were evaluated in an electron beam facility under different heat loads and cooling conditions. The surface temperature and bulk temperature distribution were carefully measured by optical pyrometers and thermocouples under a steady state heat flux of 1 to 5 MW/m^2 and a water flow rate of 3 m^3/h, 4.5 m^3/h and 6 m^3/h, respectively. It was found that the surface temperature increased rapidly with the heat flux rising, but decreased only slightly with the water flow rate rising. The surface temperature reached approximately 1200℃ at 5 MW/m^2 of heat flux and 6 m^3/h of water flow. The primary experimental results indicate that the integrated design meets the requirements for the heat expelling capacity of the HT-7 device. A set of numerical simulations was also completed, whose outcome was in good accord with the experimental results.
文摘Rapidly solidified aging is an effective way to refine the microstructure of Cu-Cr-Sn-Zn lead frame alloy and enhance its hardness. The artificial neural network methodology(ANN) along with genetic algorithms were used for data analysis and optimization. In this paper the input parameters of the artificial neural network (ANN) are the aging temperature and aging time. The outputs of the ANN model are the hardness and conductivity properties. Some explanations of these predicted results from the microstructure and precipitation-hardening viewpoint are given. After the ANN model is trained successfully, genetic algorithms(GAs) are applied for optimizing the aging processes parameters.
文摘Copper alloys suitable for laser cladding on cast iron are selected trom rune types of conventional powders. There are a poor spreading ability and porosity of copper alloy over the surface of castiron. Copper alloy surface is easily oxidized in atmosphere. These shortages have been overcome by ad- ding deoxidizers of Si and H_3BO_3. Laser parameters, stress and coefficient of friction have been ex- amined, and the larger smooth surface of Cu/cast iron for friction by laser cladding has been made for the application of the guide shoes of machine.
文摘The experimental investigation of different transition metals was carried out in the diffusion bonding joints of Cu alloys (CuAlBe) to stainless steel (1Cr18Ni9Ti). The microstructure of the joint was analyzed with microscopic examination, SEM, EPMA and X ray diffraction. Following conclusions have been drawn: (1) The joint strength with the Ni interlayer was higher than that with Cu interlayer when the welding parameters were same;(2)When Ni interlayer was thinner,Al could interact with Ni and Fe,and the intermetallic compounds,such as Fe 3Al etc,were formed in the interface,which decreased the strength of the joints;(3)When the bonding temperature was higher,because of the diffusion of Cu in Ni being faster than Ni in Cu,a Kirkendall effect was produced,which also decreased the strength of the joints.
文摘The cleaning process of removing oxides on the surface of copper alloy sheetswas investigated systematically. Through optimizing, a perfect process was selected that is fit forremoving oxides on the surface. By acid pickling, all kinds of copper oxides are removedcompletely, furthermore, no poisonous gases are given out and a smooth and clean surface of copperalloys is obtained. At present, the process is applied successfully in the copper-processingindustry.
基金supported by VTT Technical Research Centre of Finland,Aalto University,Aerosint SA,and partially from European Union Horizon 2020 (No.768775)。
文摘Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.
基金the National Natural Science Foundation of China(NSFC 22102018 and 52171201)the Natural Science Foundation of Sichuan Province(2022NSFSC0194)+6 种基金the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province(2021ZYD0043)the University of Electronic Science and Technology of China for Startup Funding(A1098531023601264)the Hefei National Research Center for Physical Sciences at the Micro-scale(KF2021005)the China Postdoctoral Science Foundation funded project(2022M710601)the University of Elec-tronic Science and Technology of China for Startup Funding(Y030212059003039)the NSFC(22005291 and 22278067)University of Electronic Science and Technology of China for Startup Funding(A1098531023601356).
文摘Electroreduction of carbon dioxide(CO_(2)) into value-added chemicals offers an entrancing approach to main-taining the global carbon cycle and eliminating environmental threats.A key obstacle to achieving long-term and large-scale implementation of electrochemical CO_(2) reduction technology is the lack of active and selective cat-alysts.Copper(Cu)is one of the few candidates that can facilitate C–C coupling to obtain high-energy oxygenates and hydrocarbons beyond carbon monoxide(CO),but it suffers from poor selectivity for products of interest and high overpotentials.Alloying is an effective way to break the linear scaling relations and uniquely manipulate the reactivity and selectivity,which is hard to achieve by using monometallic compositions alone.By alloying Cu with other metals,one could change the catalytic properties of the catalyst by tuning the local electronic structure and modulating the adsorption strength of the reaction intermediates,thus improving the catalytic activity and selectivity.In this review,we focus on the recently developed Cu-based alloy catalysts(including conventional alloys,high-entropy alloys and single-atom alloys)that have been applied in electrocatalytic CO_(2) reduction(ECR).Theoretical calculations and experimental advances in understanding the key rate-limiting and selectivity-determining steps in those alloys are summarized,with a particular focus on identifying binding energy de-scriptors and the dynamic product formation mechanisms.In addition,we outline the opportunities and chal-lenges in the fundamental understanding of ECR by recommending advanced in-situ characterization techniques and standardized electrochemical methods and offer atomic-level design principles for steering the reaction pathways to the desired products.
文摘Cu-Ni-Al alloys at different concentrations were obtained using a high frequency induction melting unit, keeping a balance in the nominal compositions. Light alloys are important to be used in industrial applications. Aluminum additions result in a positive hardness increment of the ternary alloys in comparison with the binary Cu-Ni alloys. Generalized wear mechanisms of the alloys with low aluminum content are basically type abrasive, while samples with 5 and 10 at.% Al present an oxidative-adhesive wear mechanism. Wear results have indicated that aluminum addition affects positively the wear resistance, mainly in samples with high aluminum content product of the creation during the test of different oxides corresponding to the elements present in the alloys.
文摘Microstructures have profound effects on the hardness and strength of Cu-Cr alloys. The microstructures of a Cu-Cr alloy cast in a water-cooled copper mold were studied in the present work. The scanning electron microscopy (SEM) results show that there are the copper matrix saturated with chromium, spherical precipitates of chromium separated from liquid phase during cooling before the initiation of so- lidification, and a eutectic phase in grain boundary areas. To investigate the effect of age-hardening treatment on the microstructures and properties of the material, some samples were subsequently age-hardened in a salt bath and investigated by transmission electron microscopy (TEM). The results show that coherent precipitates with the diameter of 11 nm are detectable in the samples before and after the age-hardening stage. Of course, the volume fraction of coherent precipitates is higher after the aging process.
基金financially supported by the Applied Basic Research Key Project of Yunnan Province in China(No.2011FA007)the Specialized Research Fund for Doctoral Program of Higher Education(No.20125314120013)+1 种基金the Applied Basic Research General Program of Yunnan Province in China(No.2014FB131)the Development Research Fund from Sichuan University of Science and Engineering(No.2013PY05)
文摘The compression tests were carried out by Gleeble-1500 thermo-mechanical simulator with samples of semi-solid ZCuSnl0 alloy prepared by strain-induced melt activation (SIMA) process. The original microstruc- ture and the deformation temperature of semi-solid ZCuSnl0 alloy are different. The strain is 0.2, and the strain rate is 1 s-1 for the compression test. The results show that when the semi-solid ZCuSnl0 alloy was pre- pared by SIMA process, the liquid fraction of semi-solid microstructure increases, and the solid grain is smaller, more uniform and more inclined to be round as the roiling pre-deformation increasing. The results also indicate that the deformation resistance of ZCuSnl0 alloy in semi-solid state decreases with the deformation temperature increas- ing or the solid fraction of original microstructure de- creasing. The stress-strain curves of the isothermal compression can be divided into quasi-elastic deformation stage and plastic deformation stage, and there are three deformation zones in the samples after isothermal com- pression, namely the difficult deformation zone, the large deformation zone and the free deformation zone. In the three deformation zones, the main deformation mechanism is flow of liquid incorporating solid particles (FLS) mechanism, plastic deformation of solid particles (PDS) mechanism and liquid flow (LF) combining with FLS mechanism, respectively.
基金financially supported by the National Natural Science Foundation of China (Nos. 11175014, 50971030)the National Basic Research Program of China (No. 11163110)the National Magnetic Confinement Fusion Program (No. 2011GB108002)
文摘The microstructure and nano-hardness of the pure copper and oxide dispersion-strengthened(ODS) copper alloy subjected to 1.4 Me V Au ions irradiation at room temperature were investigated. After irradiation, dislocation-loops form in both materials, while voids can only be generated in the pure copper. Compared with the irradiated pure copper, larger average diameter and lower number density of irradiation-induced dislocation-loops were detected in the ODS copper alloy, revealing that high-density dislocation and large volume of Al2O3 particles existing in the ODS copper alloy can act as effective sinks for the irradiation-induced defects. It was also detected that irradiation hardening in the ODS copper alloy is lower than that in the pure copper. The microstructure and nano-hardness results reveal that the ODS copper alloy has a better irradiation tolerance than the pure copper. In addition, the average diameter of the Al2O3 particles in the ODS copper alloy decreases after irradiation, because the Al–O chemical bonds are decomposed and the atoms are redistributed in the matrix during the irradiation process. This work reveals that the irradiation tolerance of the copper can be effectively enhanced by adding nano-sized Al2O3 particles into the matrix.
文摘By means of Precipitation hardening, a cast copper alloy with high strength and heatresistance named Cu-6Ti-Cr-Al has been developed. This alloy has good castability. After water quenching at 860℃ for 1 h and aging at 450℃ for 4 h, the tensile strength, σ_b, is greater than 890MPa and the compressive strength, σ_(bc), reaches 1300MPa, while the ratio of compression, ε_c, is maintained at 20%. When the environmental temperature is raised to 450℃, the mechanical properties do not show any appreciable loss. These copper alloy castings have been used on the roll sleeves of rubber formers and the journal bearings of sheet mills. The results have shown that the service life of these parts is much longer than that of aluminium bronze and 904alloy castings. In the present work, the microstructure, mechanical properties and strengthening mechanism were investigated.
文摘Choosing two different elements of rare earth, the absorptivity of them on copper and its alloys were researched from the category of rare earth, melting point, adding methods, casting temperature, time of heat preservation, quantity of rare earth additives etc. The laws of affecting the absorptivity are found through the research. The distributing of rare earth, existent state and the formed compounds on copper and its alloys were observed in the casting state. The absorptivities of rare earth on copper and its alloys were analyzed.