scholarly journals Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Qingzhong Mao ◽  
Yusheng Zhang ◽  
Yazhou Guo ◽  
Yonghao Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Yield Strength ◽  
High Speed ◽  
Copper Wire ◽  
Rapid Development ◽  
Dislocation Slip ◽  
Ultrafine Grains ◽  
The Wire

AbstractThe rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

scholarly journals Effects of Substitution of Y with Yb and Ce on the Microstructures and Mechanical Properties of Mg88.5Zn5Y6.5

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Hongxin Liao ◽  
Taekyung Lee ◽  
Jiangfeng Song ◽  
Jonghyun Kim ◽  
Fusheng Pan
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Creep Resistance ◽  
Room Temperature ◽  
High Thermal Stability ◽  
Long Period ◽  
Microstructures And Mechanical Properties

The microstructures and mechanical properties of the Mg88.5Zn5Y6.5-XREX (RE = Yb and Ce, X = 0, 1.5, 3.0, and 4.5) (wt.%) alloys were investigated in the present study. Mg88.5Zn5Y6.5 is composed of three phases, namely, α-Mg, long-period stacking ordered (LPSO) phases, and intermetallic compounds. The content of the LPSO phases decreased with the addition of Ce and Yb, and no LPSO phases were detected in Mg88.5Zn5Y2.0Yb4.5. The alloys containing the LPSO phases possessed a stratified microstructure and exhibited excellent mechanical properties. Mg88.5Zn5Y5.0Ce1.5 exhibited the highest creep resistance and mechanical strength at both room temperature and 200 °C, owing to its suitable microstructure and high thermal stability. The yield strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature was 358 MPa. The ultimate tensile strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature and 200 °C was 453 MPa and 360 MPa, respectively.

scholarly journals Microstructure Characteristics and Strengthening Behavior of Cu-Bearing Non-Oriented Silicon Steel: Conventional Process versus Strip Casting

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1815
Author(s):  
Feng Fang ◽  
Diwen Hou ◽  
Zhilei Wang ◽  
Shangfeng Che ◽  
Yuanxiang Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
High Speed ◽  
Silicon Steel ◽  
Strip Casting ◽  
Precipitation Strengthening ◽  
Conventional Process ◽  
Core Losses ◽  
The Matrix ◽  
Bcc Structure

Based on conventional hot rolling processes and strip casting processes, Cu precipitation strengthening is used to improve the strength of non-oriented silicon steel in order to meet the requirements of high-speed driving motors of electric vehicles. Microstructure evolution was studied, and the effects of Cu precipitates on magnetic and mechanical properties are discussed. Compared with conventional processes, non-oriented silicon steel prepared by strip casting exhibited advantages with regard to microstructure optimization with coarse grain and {100} texture. Two-stage rolling processes were more beneficial for uniform microstructure, coarse grains and improved texture. The high magnetic induction B50 of 1.762 T and low core losses with P1.5/50, P1.0/400 and P1.0/1000 of 1.93, 11.63 and 44.87 W/kg, respectively, were obtained in 0.20 mm sheets in strip casting. Cu precipitates significantly improved yield strength over ~120 MPa without deteriorating magnetic properties both in conventional process and strip casting. In the peak stage aged at 550 °C for 120 min, Cu precipitates retained bcc structure and were coherent with the matrix, and the yield strength of the 0.20 mm sheet was as high as 501 MPa in strip casting. The main mechanism of precipitation strengthening was attributed to coherency strengthening and modulus strengthening. The results indicated that balanced magnetic and mechanical properties can be achieved in thin-gauge non-oriented silicon steel with Cu addition in strip casting.

Thermal Stability of Mechanical Properties of Copper after Equal-Channel Angular Pressing

2008 ◽  
Vol 584-586 ◽  
pp. 960-965 ◽  
Author(s):  
Tamara Kravchenko ◽  
Alexander Korshunov ◽  
Natalia Zhdanova ◽  
Lev Polyakov ◽  
Irina Kaganova
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Chemical Composition ◽  
Yield Strength ◽  
Equal Channel Angular Pressing ◽  
Angular Pressing ◽  
Different Temperatures ◽  
Thermal Stability Of

Annealed oxygen-free and tough-pitch copper samples have been processed by equalchannel angular pressing (ECAP) by route BC. The samples included 8 x 8 mm section pieces and a 40 mm diameter bar. Thermal stability was assessed based on the changes in the standard mechanical properties (conventional yield strength, tensile strength, elongation, proportional elongation and contraction) after annealing at different temperatures for 1 hour. Thermal stability of the same grade of material has been found to be different for different batches and to depend on the structural conditions of deformed material. The zone of thermal stability for copper of the two grades of interest does not depend on the material’s chemical composition.

Microstructure and Mechanical Properties of Mg96Y3Zn1 Alloy Processed by Equal Channel Angular Pressing

2011 ◽  
Vol 682 ◽  
pp. 49-54
Author(s):  
Bin Chen ◽  
Chen Lu ◽  
Dong Liang Lin ◽  
Xiao Qin Zeng
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Tensile Test ◽  
Equal Channel Angular Pressing ◽  
Ultrafine Grains ◽  
Angular Pressing ◽  
Average Grain Size

The Mg96Y3Zn1 alloy processed by equal channel angular pressing has been investigated. It was found that the Mg96Y3Zn1 alloy processed by ECAP obtained ultrafine grains and exhibits excellent mechanical properties. After ECAP, the average grain size of Mg96Y3Zn1 alloy refined to about 400 nm. The highest strengths with yield strength of 381.45MPa and ultimate tensile strength of 438.33MPa were obtained after 2 passes at 623K. It was found that cracks were preferentially initiated and propagated in the interior of X-phase during the tensile test. As a result, the elongation of alloy is decreased with pass number increasing.

Preparation of poly(ether ether ketone)-based composite with high electrical conductivity, good mechanical properties and thermal stability

2016 ◽  
Vol 29 (2) ◽  
pp. 205-210 ◽  
Author(s):  
Yu Jin Lin ◽  
Shi Qin ◽  
Bing Han ◽  
Cong Gao ◽  
Shu Ling Zhang
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
High Electrical Conductivity ◽  
Aryl Ether ◽  
Good Thermal Stability ◽  
Ether Ether Ketone ◽  
Peek Composite ◽  
Poly Ether Ether Ketone ◽  
Ether Ketone

Poly(ether ether ketone)-based (PEEK-based) composites with high electrical conductivity, good mechanical properties, and thermal stability were prepared using multiwall carbon nanotubes (MWCNTs) as a conductive filler and the liquid crystalline copolymer of poly(aryl ether ketone) (FPEDEKKLCP) as a processing aid. The composites were fabricated using melt blending, and the MWCNT/PEEK composites with FPEDEKKLCP exhibited an obvious improvement in the measured electrical conductivity relative to the MWCNT/PEEK composite without FPEDEKKLCP. Moreover, the MWCNT/PEEK composites exhibited good mechanical properties and thermal stability after addition of an appropriate amount of FPEDEKKLCP. This is attributed to the good thermal stability of FPEDEKKLCP, wherein addition of FPEDEKKLCP effectively decreased the melt viscosity of the MWCNT/PEEK composites, accompanied by an improvement in the dispersion of the MWCNTs in the PEEK matrix.

scholarly journals Assessing the Critical Multifunctionality Threshold for Optimal Electrical, Thermal, and Nanomechanical Properties of Carbon Nanotubes/Epoxy Nanocomposites for Aerospace Applications

Aerospace ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 7 ◽  
Author(s):  
Aikaterini-Flora Trompeta ◽  
Elias Koumoulos ◽  
Sotirios Stavropoulos ◽  
Theodoros Velmachos ◽  
Georgios Psarras ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Critical Concentration ◽  
Epoxy Composites ◽  
Micro Computed Tomography ◽  
Epoxy Nanocomposites ◽  
Aerospace Structures ◽  
Nanomechanical Properties

Epoxy composites are widely used in primary aerospace structures, where high impact damage properties are necessary. However, challenges appear when multiple functionalities, including electrical and thermal conductivity, are needed in parallel with increased mechanical properties. The current study aims at the assessment of a critical concentration of multiwalled carbon nanotubes (MWCNTs), incorporated in epoxy resin, which will indicate a threshold for optimal electrical, thermal and mechanical properties. For the evaluation of this optimal concentration, electrical conductivity, thermal stability and nanomechanical properties (Young modulus and nanohardness) have been assessed, for epoxy nanocomposites with 0 to 15 parts per hundred resin per weight (phr) MWCNTs. Percolation theory was applied to study the electrical conductivity for different contents of MWCNTs in the epoxy nanocomposite system. Thermogravimetric analysis was employed for the assessment of the epoxy composites’ thermal properties. Nanohardness and elastic modulus were measured, and the hardness versus modulus index was calculated. Emphasis was given to the dispersion of MWCNTs in the epoxy matrix, which was assessed by both microscopy techniques and X-ray micro–computed tomography. A correlation between the optimum dispersion and MWCNTs content in terms of electrical conductivity, thermal stability, and nanomechanical properties revealed a threshold concentration at 3 phr, allowing the manufacturing of aerospace structures with multifunctional properties.

Microstructure, thermal stability and mechanical properties of slowly cooled Zr-based composites containing dendritic bcc phase precipitates

2003 ◽  
Vol 806 ◽  
Author(s):  
Nicolle Radtke ◽  
Jürgen Eckert ◽  
Uta Kühn ◽  
Mihai Stoica ◽  
Ludwig Schultz
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Plastic Strain ◽  
Yield Strength ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Homogeneous Distribution ◽  
Compression Tests ◽  
Scanning Calorimetry ◽  
Bcc Phase

ABSTRACTWe report on the microstructure, the thermal stability and the mechanical properties of slowly cooled Zr-Nb-Cu-Ni-Al alloys with ductile bcc phase precipitates embedded in a glassy or nanocrystalline matrix. The samples were prepared in form of rods by injection casting into a copper mold. The phase formation and the microstructure of the composite material were investigated by X-ray diffraction, EDX analysis and scanning and transmission electron microscopy. The thermal stability was examined by differential scanning calorimetry and the mechanical behavior was investigated by compression tests under quasistatic loading at room temperature. The formation of bcc phase dendrites and a glassy or nanocrystalline matrix is strongly governed by the alloy composition and the actual cooling rate during solidification. Besides, changes in composition and cooling rate lead to different volume fraction and size of the bcc phase precipitates and, hence, to different values of yield strength, elastic and plastic strain. The samples with nanocrystalline matrix show a homogeneous distribution of the bcc phase precipitates over the whole cross-section and exhibit higher yield strength and plastic strain than the samples containing an amorphous matrix. Illustrated by the presented results we show the possibility of obtaining tailored mechanical properties by control of composition and solidification conditions.

Properties of Multi-Walled Carbon Nanotube / Polymethyl Methacrylite Nanocomposite Prepared via a Modified Coagulation Method

2011 ◽  
Vol 341-342 ◽  
pp. 199-203
Author(s):  
Ismail Noor Mazni ◽  
Aziz Azizan ◽  
Mariatti Jaafar
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Flexural Modulus ◽  
Flexural Test ◽  
Surface Fracture ◽  
Thermo Gravimetric ◽  
Thermo Gravimetric Analyzer ◽  
Multi Walled Carbon Nanotube ◽  
Mwcnt Concentration

The aim of this study is to produce MWCNT/PMMA nanocomposite with enhanced properties through a modified coagulation method. Samples were prepared in respect to various high filler loadings (1%, 3%, 5%, 7% and 10% wt.). Standard ASTM D790 flexural test was used to evaluate the mechanical properties of the composites. The morphology and surface fracture was observed via Scanning Electron Microscopy (SEM). Thermal stability and electrical conductivity of the composites as a function of MWCNT concentration were measured using Thermo Gravimetric Analyzer (TGA) and UHT Meter, respectively. Flexural strength and flexural modulus of MWCNT/PMMA nanocomposite showed an improvement up to 24.1% and 107.7% compared to the neat PMMA. It was found that the thermal stability and electrical conductivity of the MWCNT/PMMA nanocomposite improved as the concentration of the MWCNT filler increased. These studies therefore demonstrated that MWCNT/PMMA nanocomposite prepared via a modified coagulation method able to successfully improve thermal stability, electrical conductivity and mechanical properties of PMMA.

Experimental study of the simultaneous effects of severe plastic deformation and secondary radial strain on copper

2021 ◽  
pp. 095440892110244
Author(s):  
Seyyed Ehsan Eftekhari Shahri ◽  
Mohammad Amin Ranaei ◽  
Hossein Jamshidi ◽  
Elyas Rezaei
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Copper Wire ◽  
Pure Copper ◽  
Radial Strain ◽  
High Strength ◽  
Homogeneous Structure ◽  
Direct Extrusion

Due to the widespread use of copper wires in electrical power transmission, the need for raw materials with a homogeneous structure and high strength while maintaining their conductive properties is of high importance. The present study investigates the production of copper wire with improved mechanical properties and homogeneous microstructure due to its nanometre-sized structure. Therefore, the commercial pure copper specimens were subjected to severe plastic deformation (SPD) by means of equal channel angular pressing (ECAP) during four steps at ambient temperature. Due to the creation of a structure with elongated grains in the ECAP process, the deformed specimens were subjected to the direct extrusion operations; thus, a more homogeneous structure was created in them due to the appearance of a secondary radial strain. The obtained results indicate that by applying the simultaneous effects of SPD and direct extrusion on the microstructure, the mechanical properties such as strength and hardness have improved significantly, while the electrical conductivity of pure copper decreased slightly. The outcome can be used as an alternative to current methods for producing high-strength copper wires with suitable electrical conductivity properties.

scholarly journals Microstructure, Mechanical Properties, and Thermal Stability of Carbon-Free High Speed Tool Steel Strengthened by Intermetallics Compared to Vanadis 60 Steel Strengthened by Carbides

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1901
Author(s):  
Alena Michalcová ◽  
Vojtěch Pečinka ◽  
Zdeněk Kačenka ◽  
Jan Šerák ◽  
Jiří Kubásek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tool Steel ◽  
High Speed ◽  
Intermetallic Phase ◽  
High Hardness ◽  
Thermal Exposure ◽  
Machining Process ◽  
Material Utilization ◽  
Thermal Stability Of

High speed tool steels are materials that exhibit superior mechanical properties (e.g., high hardness). They should also be resistant to thermal exposure to maintain high hardness during the machining process. In this paper, a C-free tool steel formed of Fe matrix and a Mo6Co7 intermetallic phase was studied. This steel was compared to the well-known Vanadis 60 steel containing Fe matrix and carbides. Microstructures were investigated by scanning (SEM) and transmission (TEM) electron microscopy, and the mechanical properties and thermal stability of both materials were compared. It was proven that the strengthening in the Vanadis 60 steel was mainly caused by the carbides, while the C-free steel was strengthened by the Mo6Co7 phase. The hardness values of both materials were comparable in the utilization state (approx. 950 HV). The hardness of Vanadis 60 steel decreased after several minutes of annealing at 650 °C under the value that enables material utilization. The hardness value of the steel strengthened by the intermetallics also decreased but significantly slower. Based on these results, the main finding of this study is that the C-free steel exhibited much better thermal stability and may be utilized at higher temperatures for longer periods of time than Vanadis 60.

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