In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al-0.16 Zr, Al-0.16 Sc, Al-0.12Sc-0.04Zr（mass fraction, %） and pure Al（99.996%） were produced...In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al-0.16 Zr, Al-0.16 Sc, Al-0.12Sc-0.04Zr（mass fraction, %） and pure Al（99.996%） were produced with the diameter of 9.5 mm by continuous rheo-extrusion technology, and the extruded materials were heat treated and analyzed. The results show that the separate additions of 0.16% Sc and 0.16% Zr to pure Al improve the ultimate tensile strength but reduce the electrical conductivity, and the similar trend is found in the Al-0.12Sc-0.04 Zr alloy. After the subsequent heat treatment, the wire with the optimum comprehensive properties is Al-0.12Sc-0.04 Zr alloy, of which the ultimate tensile strength and electrical conductivity reach 160 MPa and 64.03%（IACS）, respectively.展开更多
The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investig...The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrated Rogowski coil and a voltage divider were used for the measurements of current and voltage at the wire load, respectively. The deposited energy before breakdown was calculated based on experimental waveforms of current and voltage by mathematical method. Effects of the applied voltage, circuit inductance and sion and energy deposition were analyzed by means parameters of Al wire on the electrical exploof experiments and calculation. The results show that the current rise rate has an important influence on explosion process, such as the energy deposition before breakdown, the electrical power as well as the various explosion stages. A higher current rise rate can be achieved by increasing applied voltage and decreasing circuit inductance. The inhomogeneity of the energy deposition will result in prematured breakdown as well as lowered energy deposition, making the explosion process of wire more complicated.展开更多
The trade-off relation between the strength and the electrical conductivity has been a Iong-standing dilemma in metallic materials. In the study, three key principles, i.e.elongated grains, sharp texture and nano-scal...The trade-off relation between the strength and the electrical conductivity has been a Iong-standing dilemma in metallic materials. In the study, three key principles, i.e.elongated grains, sharp texture and nano-scale precipitates, were presented for preparing Al wire with high strength and high electrical conductivity based on the specially designed experiments for breaking the mutually exclusive relation between the strength and the electrical conductivity. The results show that the elongated grains could lead to a higher electrical conductivity in Al wire without sacrificing the strength;while, the <111> sharp texture can efficiently strengthen the Al wire without influencing the electrical conductivity. Furthermore, nano-scale precipitates with proper size can simultaneously improve the strength and electrical conductivity of Al alloy wire. Under the guidance of the above three key principles, Al wires with high strength and high conductivity were prepared.展开更多
The effect of different regimes of heat treatment on the tensile strength of SiC coated composite of C fibers reinforced Al wires has been investigated.Their tensile strength may increase under treatment either at 500...The effect of different regimes of heat treatment on the tensile strength of SiC coated composite of C fibers reinforced Al wires has been investigated.Their tensile strength may increase under treatment either at 500℃ for 2h or 550℃ for 1h,but decrease over 600℃.After the strength tests of extracted fibers from composite wires,the SiC coating is an excellent protection to C fibers.EPMA and EDAX showed that the C/Al interface of the composite wires is stable under treatment below 600℃,but unstable at 650℃展开更多
The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The me...The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The metallurgic morphology and distribution of the chemical compositions were determined using imaging techniques such as optical micrograph, scanning electron micrograph, high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry and X-ray diffraction. Corrosion was evaluated using an immersion test and electrochemical impedance spectroscopy in 3.5% NaC1 solution at room temperature. Results indicate that the parent alloy suffered from pitting corrosion during the initial 4-h immersion which was caused by the inhomogeneous distribution of its chemical compo- nents and the different intermetallics formed during the rolling process. The weld experienced dendritic boundary corrosion under the same conditions due to the addition of the Al-Cu filler and rapid solidification during laser welding, which led to the precipitates Cu enrichment along the grain boundary. When a welding joint was immersed in the solution for 5 days, a big crack was observed across the center of the weld. In comparison, there was good corrosion resistance in the heat- affected zone with a compact protective film.展开更多
Cored wires for electric arc spraying of Al/Al 2 O 3 MMC coatings were developed, with Al 2 O 3 powder as the core material and commercial aluminium strip as the retaining sheath. The bond strength, ...Cored wires for electric arc spraying of Al/Al 2 O 3 MMC coatings were developed, with Al 2 O 3 powder as the core material and commercial aluminium strip as the retaining sheath. The bond strength, Al 2 O 3 content, microstructure, micro-hardness and wear resistance of coatings produced by arc spraying of the cored wires were experimentally investigated and were compared with those of pure aluminum coating.展开更多
Gd50Al3oCo20 wires show excellent magnetocaloric properties and high heat exchange rate due to the microsize. The Weibull and lognormal methods were used for systematically analyzing its mechanical properties for matc...Gd50Al3oCo20 wires show excellent magnetocaloric properties and high heat exchange rate due to the microsize. The Weibull and lognormal methods were used for systematically analyzing its mechanical properties for matching the design requirements in cooling system. The wire exhibits average fracture strength of-969.5 MPa and typical fracture behavior of amorphous character. Moreover, the distributions of stresses for tensile strains at 10 values are estimated by probability plot and Chi-square goodness-of-fit test. The random stresses were best fitted by lognormal probability distribution for most studied cases; however, fracture strength was best fitted by Weibull probability distribution. It is interesting to note that the mean and standard deviation of the stresses （to reach specific tensile strain） increase as the tensile strain grows, accompanied by the coefficients of variation of stresses which decrease smoothly. It is concluded that the inhomogeneity of material does cause the scatter of stresses growth, and the scatter could be considerably large.展开更多
Twin wire weld temperature results calculated by classical double ellipsoid heat source model are bigger than the experimental results. By analyzing the shape of twin wire welding arcs and the track of droplets transi...Twin wire weld temperature results calculated by classical double ellipsoid heat source model are bigger than the experimental results. By analyzing the shape of twin wire welding arcs and the track of droplets transition, the phenomena that both the fore arc and rear arc of twin wire welding deflect to the middle of the two arcs is found. Based on this the double ellipsoid heat source model is amended, and a heat source model which can be applied to calculate the temperature field of twin wire welding was put forward. This model is testified by actual experiment of temperature sampling. Then, the evolution regularities of longitudinal and transverse stress for 2219 sheets were investigated under the condition of twin wire welding. The result shows that longitudinal residual stress value of twin wire welding is 10% higher than that of the single wire welding.展开更多
The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding (LBW) and laser welding with filler wire (LWFW) were studied and analyzed.The results indic...The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding (LBW) and laser welding with filler wire (LWFW) were studied and analyzed.The results indicated that the microstructure of joint by LWFW was fine-grained layer and the equiaxed grain in most of seams,which were similar to the joint by LBW.Compared with the joint by LBW,the microstructure of joint by LWFW tended to fine,and the range of the columnar crystals zone was prone to decrease.The Microhardness of the joint by LWFW (92.57HV0.2) was lower than that by LBW (95.65HV0.2),but the uniformity was better.The ultimate tensile strength of the joint by LWFW was lower than that by LBW slightly,which reached to 73.03% and 79.22% of the base metal respectively.However,the elongation of the LWFW joint was higher than that of the LBW joint significantly,which reached to 38.65% and 20.38% of the base metal respectively.The microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW were better than that by LBW.The defects of joint were mainly forming defects which were caused by improper parameters and porosity inside the joint,which was caused by uncleaned surface and incomplete penetration.展开更多
基金Project(51222405)supported by the National Natural Science Foundation for Outstanding Young Scholars of ChinaProject(51034002)supported by the National Natural Science Foundation of ChinaProject(120502001)supported by the Fundamental Research Funds for the Central Universities of China
文摘In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al-0.16 Zr, Al-0.16 Sc, Al-0.12Sc-0.04Zr（mass fraction, %） and pure Al（99.996%） were produced with the diameter of 9.5 mm by continuous rheo-extrusion technology, and the extruded materials were heat treated and analyzed. The results show that the separate additions of 0.16% Sc and 0.16% Zr to pure Al improve the ultimate tensile strength but reduce the electrical conductivity, and the similar trend is found in the Al-0.12Sc-0.04 Zr alloy. After the subsequent heat treatment, the wire with the optimum comprehensive properties is Al-0.12Sc-0.04 Zr alloy, of which the ultimate tensile strength and electrical conductivity reach 160 MPa and 64.03%（IACS）, respectively.
基金supported by the State Key Program of National Natural Science Foundation of China(No.50637010)
文摘The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrated Rogowski coil and a voltage divider were used for the measurements of current and voltage at the wire load, respectively. The deposited energy before breakdown was calculated based on experimental waveforms of current and voltage by mathematical method. Effects of the applied voltage, circuit inductance and sion and energy deposition were analyzed by means parameters of Al wire on the electrical exploof experiments and calculation. The results show that the current rise rate has an important influence on explosion process, such as the energy deposition before breakdown, the electrical power as well as the various explosion stages. A higher current rise rate can be achieved by increasing applied voltage and decreasing circuit inductance. The inhomogeneity of the energy deposition will result in prematured breakdown as well as lowered energy deposition, making the explosion process of wire more complicated.
基金financially supported by the State Grid Corporation of China (No. 52110416001z)the National Natural Science Foundation of China (No. 51331007)
文摘The trade-off relation between the strength and the electrical conductivity has been a Iong-standing dilemma in metallic materials. In the study, three key principles, i.e.elongated grains, sharp texture and nano-scale precipitates, were presented for preparing Al wire with high strength and high electrical conductivity based on the specially designed experiments for breaking the mutually exclusive relation between the strength and the electrical conductivity. The results show that the elongated grains could lead to a higher electrical conductivity in Al wire without sacrificing the strength;while, the <111> sharp texture can efficiently strengthen the Al wire without influencing the electrical conductivity. Furthermore, nano-scale precipitates with proper size can simultaneously improve the strength and electrical conductivity of Al alloy wire. Under the guidance of the above three key principles, Al wires with high strength and high conductivity were prepared.
文摘The effect of different regimes of heat treatment on the tensile strength of SiC coated composite of C fibers reinforced Al wires has been investigated.Their tensile strength may increase under treatment either at 500℃ for 2h or 550℃ for 1h,but decrease over 600℃.After the strength tests of extracted fibers from composite wires,the SiC coating is an excellent protection to C fibers.EPMA and EDAX showed that the C/Al interface of the composite wires is stable under treatment below 600℃,but unstable at 650℃
基金financially supported by the National Natural Science Foundation of China (Grant Number: 51505010)Beijing Natural Science Foundation (Grant Number: 2152007)
文摘The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The metallurgic morphology and distribution of the chemical compositions were determined using imaging techniques such as optical micrograph, scanning electron micrograph, high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry and X-ray diffraction. Corrosion was evaluated using an immersion test and electrochemical impedance spectroscopy in 3.5% NaC1 solution at room temperature. Results indicate that the parent alloy suffered from pitting corrosion during the initial 4-h immersion which was caused by the inhomogeneous distribution of its chemical compo- nents and the different intermetallics formed during the rolling process. The weld experienced dendritic boundary corrosion under the same conditions due to the addition of the Al-Cu filler and rapid solidification during laser welding, which led to the precipitates Cu enrichment along the grain boundary. When a welding joint was immersed in the solution for 5 days, a big crack was observed across the center of the weld. In comparison, there was good corrosion resistance in the heat- affected zone with a compact protective film.
文摘Cored wires for electric arc spraying of Al/Al 2 O 3 MMC coatings were developed, with Al 2 O 3 powder as the core material and commercial aluminium strip as the retaining sheath. The bond strength, Al 2 O 3 content, microstructure, micro-hardness and wear resistance of coatings produced by arc spraying of the cored wires were experimentally investigated and were compared with those of pure aluminum coating.
基金The authors are thankful for the supports from the Key National Natural Science Foundation of China （No. U1533202）, the Shandong Independent Innovation and Achievements Transformation Fund （No. 2014CGZHl101）, the Civil Aviation Administration of China （No. MHRD20150104）, National Sciencetechnology Support Plan Project ＂the application paradigm of full lifecycle information closed-loop management for construction machinery＂ （No. 2015BAF32B01-4） and National Natural Science Foundation of China （Nos. 51775132, 51671071 and 51371067）.
文摘Gd50Al3oCo20 wires show excellent magnetocaloric properties and high heat exchange rate due to the microsize. The Weibull and lognormal methods were used for systematically analyzing its mechanical properties for matching the design requirements in cooling system. The wire exhibits average fracture strength of-969.5 MPa and typical fracture behavior of amorphous character. Moreover, the distributions of stresses for tensile strains at 10 values are estimated by probability plot and Chi-square goodness-of-fit test. The random stresses were best fitted by lognormal probability distribution for most studied cases; however, fracture strength was best fitted by Weibull probability distribution. It is interesting to note that the mean and standard deviation of the stresses （to reach specific tensile strain） increase as the tensile strain grows, accompanied by the coefficients of variation of stresses which decrease smoothly. It is concluded that the inhomogeneity of material does cause the scatter of stresses growth, and the scatter could be considerably large.
文摘Twin wire weld temperature results calculated by classical double ellipsoid heat source model are bigger than the experimental results. By analyzing the shape of twin wire welding arcs and the track of droplets transition, the phenomena that both the fore arc and rear arc of twin wire welding deflect to the middle of the two arcs is found. Based on this the double ellipsoid heat source model is amended, and a heat source model which can be applied to calculate the temperature field of twin wire welding was put forward. This model is testified by actual experiment of temperature sampling. Then, the evolution regularities of longitudinal and transverse stress for 2219 sheets were investigated under the condition of twin wire welding. The result shows that longitudinal residual stress value of twin wire welding is 10% higher than that of the single wire welding.
文摘The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding (LBW) and laser welding with filler wire (LWFW) were studied and analyzed.The results indicated that the microstructure of joint by LWFW was fine-grained layer and the equiaxed grain in most of seams,which were similar to the joint by LBW.Compared with the joint by LBW,the microstructure of joint by LWFW tended to fine,and the range of the columnar crystals zone was prone to decrease.The Microhardness of the joint by LWFW (92.57HV0.2) was lower than that by LBW (95.65HV0.2),but the uniformity was better.The ultimate tensile strength of the joint by LWFW was lower than that by LBW slightly,which reached to 73.03% and 79.22% of the base metal respectively.However,the elongation of the LWFW joint was higher than that of the LBW joint significantly,which reached to 38.65% and 20.38% of the base metal respectively.The microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW were better than that by LBW.The defects of joint were mainly forming defects which were caused by improper parameters and porosity inside the joint,which was caused by uncleaned surface and incomplete penetration.
