scholarly journals Interpretation of Specific Strength-Over-Resistivity Ratio in Cu Alloys

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7150
Author(s):  
Hongming Li ◽  
Shuang Zhang ◽  
Yajun Zhao ◽  
Xiaona Li ◽  
Fushi Jiang ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Lower Limit ◽  
High Strength ◽  
Alloy System ◽  
Resistivity Ratio ◽  
Specific Strength ◽  
Cu Alloys ◽  
The Matrix ◽  
In Series ◽  
Pure Cu

Reaching simultaneously high mechanical strength and low electrical resistivity is difficult as both properties are based on similar microstructural mechanisms. In our previous work, a new parameter, the tensile strength-over-electrical resistivity ratio, is proposed to evaluate the matching of the two properties in Cu alloys. A specific ratio of 310 × 108 MPa·Ω−1·m−1, independent of the alloy system and thermal history, is obtained from Cu-Ni-Mo alloys, which actually points to the lower limit of prevailing Cu alloys possessing high strength and low resistivity. The present paper explores the origin of this specific ratio by introducing the dual-phase mechanical model of composite materials, assuming that the precipitate particles are mechanically mixed in the Cu solid solution matrix. The strength and resistivity of an alloy are respectively in series and parallel connections to those of the matrix and the precipitate. After ideally matching the contributions from the matrix and the precipitate, the alloy should at least reach half of the resistivity of pure Cu, i.e., 50%IACS, which is the lower limit for industrially accepted highly conductive Cu alloys. Under this condition, the specific 310 ratio is related to the precipitate-over-matrix ratios for strength and resistivity, which are both two times those of pure Cu.

scholarly journals Accelerated discovery of high-strength aluminum alloys by machine learning

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Jiaheng Li ◽  
Yingbo Zhang ◽  
Xinyu Cao ◽  
Qi Zeng ◽  
Ye Zhuang ◽  
...  
Keyword(s):  
Machine Learning ◽  
Aluminum Alloys ◽  
Mechanical Performance ◽  
High Strength ◽  
Cost Effective ◽  
Alloy System ◽  
Processing Route ◽  
Specific Strength ◽  
Cu Alloy ◽  
High Strength Aluminum Alloys

Abstract Aluminum alloys are attractive for a number of applications due to their high specific strength, and developing new compositions is a major goal in the structural materials community. Here, we investigate the Al-Zn-Mg-Cu alloy system (7xxx series) by machine learning-based composition and process optimization. The discovered optimized alloy is compositionally lean with a high ultimate tensile strength of 952 MPa and 6.3% elongation following a cost-effective processing route. We find that the Al8Cu4Y phase in wrought 7xxx-T6 alloys exists in the form of a nanoscale network structure along sub-grain boundaries besides the common irregular-shaped particles. Our study demonstrates the feasibility of using machine learning to search for 7xxx alloys with good mechanical performance.

Mechanical Properties of Densified Untwisted Carbon Nanotube Yarn / Epoxy Composites

2015 ◽  
Author(s):  
Risa Yoshizaki ◽  
Kim Tae Sung ◽  
Atsushi Hosoi ◽  
Hiroyuki Kawada
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Polymer Matrix Composites ◽  
High Strength ◽  
Matrix Composites ◽  
Specific Strength ◽  
The Matrix ◽  
Cnt Arrays ◽  
Strength And Stiffness ◽  
Long Fibers

Carbon nanotubes (CNTs) have very high specific strength and stiffness. The excellent properties make it possible to enhance the mechanical properties of polymer matrix composites. However, it is difficult to use CNTs as the reinforcement of long fibers because of the limitation of CNT growth. In recent years, a method to spin yarns from CNT forests has developed. We have succeeded in manufacturing the unidirectional composites reinforced with the densified untwisted CNT yarns. The untwisted CNT yarns have been manufactured by drawing CNTs through a die from vertically aligned CNT arrays. In this study, the densified untwisted CNT yarns with a polymer treatment were fabricated. The tensile strength and the elastic modulus of the yarns were improved significantly by the treatment, and they were 1.9 GPa and 140 GPa, respectively. Moreover, the polymer treatment prevented the CNT yarns from swelling due to impregnation of the matrix resin. Finally, the high strength CNT yarn composites which have higher volume fraction than a conventional method were successfully fabricated.

Long-Range Ordering: An Approach to Synthesize Nanoscale Ni-Mo-Based Superlattices with High Strength and High Ductility

2009 ◽  
Vol 633-634 ◽  
pp. 421-435 ◽  
Author(s):  
H.M. Tawancy
Keyword(s):  
Long Range ◽  
Tensile Elongation ◽  
Aging Treatment ◽  
High Strength ◽  
Alloy System ◽  
Chemical Compositions ◽  
Atomic Order ◽  
High Ductility ◽  
The Matrix ◽  
Long Range Ordering

It is shown that long-range ordering in certain alloys based upon the Ni-Mo system can provide a viable means for synthesizing bulk nanoscale materials combing high strength and high ductility. Three alloys were included in the study with nominal chemical compositions of Ni-27Mo, Ni-27Mo-0.03B, and Ni-27Mo-12Cr all in weight %. Ordering was induced by thermal aging at 700 oC resulting in a D1a superlattice (Ni4Mo) in the Ni-27Mo and Ni-27Mo-0.03B alloys, and a Pt2Mo-type superlattice [Ni2(Cr,Mo)] in the Ni-27Mo-12Cr alloy. During the early stages of aging, atomic order in the Ni-27Mo alloy was completed homogeneously in the matrix resulting in a nanoscale superlattice with high strength and high ductility, however, a considerable loss of ductility occurred after extended aging. The results suggested that this behavior was not related to the degree of atomic order but rather to a change in morphology resulting from a heterogeneous ordering reaction at grain boundaries promoted by strain-induced recrystallization. Although a nanoscale superlattice combining high strength and high ductility could be synthesized in the Ni-27Mo alloy by proper aging treatment, it is demonstrated that the heterogeneous ordering reaction could be suppressed by the addition of boron or chromium to improve the thermal stability of the alloy system. On the average, a combination of about 800 MPa yield strength and 40% tensile elongation at room temperature could be achieved in the alloys studied. Deformation in the ordered state is found to occur by twinning, which has been related to the crystallography of the disorder-order transformation.

Influence of Rare Earth Elements in Magnesium Alloy - A Mini Review

2020 ◽  
Vol 979 ◽  
pp. 162-166
Author(s):  
N. Sivashanmugam ◽  
K. L. Harikrishna
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Magnesium Alloys ◽  
Biomedical Applications ◽  
High Strength ◽  
Alloy System ◽  
Damping Capacity ◽  
Specific Strength ◽  
Large Size ◽  
Strength And Ductility

In recent days, the use of Magnesium and its alloys is preferred in defence, automotive and aerospace industries where large size and complex components are required in light weight. Besides, magnesium alloys are used in computers, electronic devices and biomedical applications. Alloying magnesium with rare earth elements (RE) is used to develop the light alloys for the stated applications at elevated temperature. Rare earth magnesium alloys are having unique properties over other metals, including a high specific strength, low thermal conductivity, good damping capacity and good castability. In this review article, the recent development of rare earth magnesium alloys will be reviewed from the view point of novel alloying designs. It has been revealed that in ternary alloy system Mg-ZN-RE alloy exhibited high strength and ductility. This leads the researchers to investigate Mg-ZN-RE alloy recently.

Exploring the Use of Cork Based Composites for Aerospace Applications

2010 ◽  
Vol 636-637 ◽  
pp. 260-265 ◽  
Author(s):  
José M. Silva ◽  
Tessaleno C. Devezas ◽  
A. Silva ◽  
L. Gil ◽  
C. Nunes ◽  
...  
Keyword(s):  
Damage Tolerance ◽  
Matrix Material ◽  
High Strength ◽  
Experimental Tests ◽  
Dynamic Loads ◽  
Natural Material ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Different Types ◽  
The Matrix

Aerospace components are characterized by having high strength to weight ratios in order to obtain lightweight structures. Recently, different types of sandwich components using composite materials have been developed with the purpose of combining the effect of reinforced face-sheets with low weight core materials, such as honeycombs and foams. However, these materials must combine damage tolerance characteristics with high resistance under both static and dynamic loads. Cork composites can be considered as an alternative material for sandwich components since cork is a natural material with some remarkable properties, such as high damage tolerance to impact loads, good thermal and acoustic insulation capacities and excellent damping characteristics for the suppression of vibrations. The experiments carried out in this investigation were oriented in order to optimize the specific strength of cork based composites for sandwich components. Static bending tests were performed in order to characterize the mechanical strength of different types of cork agglomerates which were obtained considering distinct production variables. The ability to withstand dynamic loads was also evaluated from a set of impact tests using carbon-cork sandwich specimens. The results from experimental tests showed that cork agglomerates performance depends on the cork granulate size, the type of reinforcing elements and the bonding procedure used for the cohesion with the matrix material.

Fabrication Optimization of Magnesium Az61 Alloys via Extrusion for High Productivity

2011 ◽  
Vol 378-379 ◽  
pp. 727-730
Author(s):  
Joon Sik Park ◽  
Jeong Min Kim ◽  
Young Ho Song ◽  
Byung Hwan-Hong ◽  
Ye Won Cho ◽  
...  
Keyword(s):  
High Strength ◽  
Alloy System ◽  
Mg Alloys ◽  
Practical Application ◽  
Extrusion Speed ◽  
Surface Stability ◽  
High Productivity ◽  
Specific Strength ◽  
High Specific Strength ◽  
Structural Parts

The nature of high specific strength compared with other structural materials has led to wide application of Mg alloys. However, Mg alloys often exhibit relatively low strength and/or low surface stability, which can limit the practical application of the alloy system. In order to achieve high strength, the commercial AZ61 alloys were extruded, so that the application of the alloy system can be extended towards new structural parts for requiring the light nature of the alloy system. In this study, a high temperature extrusion has been carried out for the commercial Mg alloys (AZ61). The productivity and mechanical properties of the alloy were critically affected by the extrusion conditions such as temperature, extrusion ratio and extrusion speed. The texture development and alloy strengths with respect to the extrusion conditions have been discussed in terms of microstructural observations and phase analyses.

Multifunctional BN/Si3N4 and TiN/Si3N4 Nanocomposites Prepared by In Situ Nitridation Method

2007 ◽  
Vol 336-338 ◽  
pp. 2247-2250
Author(s):  
Lian Gao ◽  
Xi Hai Jin ◽  
Jing Guo Li ◽  
Takafumi Kusunose ◽  
Koichi Niihara
Keyword(s):  
Electrical Resistivity ◽  
Electrical Discharge ◽  
Phase Distribution ◽  
Electrical Discharge Machining ◽  
High Strength ◽  
Second Phase ◽  
Ammonia Gas ◽  
The Matrix

Machinable BN/Si3N4 and electroconductive TiN/Si3N4 nanocomposites were prepared, using powders synthesized through an in-situ nitridation method in flowing ammonia gas. Due to the homogeneous mixing of various components in the powders, nanocomposites with homogeneous second phase distribution in the matrix were obtained. These nanocomposites showed enhanced strengths and distinctive functionalities. BN/Si3N4 nanocomposite with 20-25vol% BN showed a relatively high strength of over 700 MPa and was able to be machined into complicated shapes with diamond bits. Electroconductive TiN/Si3N4 nanocomposite with 25vol% TiN showed a high strength of 1100MPa and low electrical resistivity of 1.1×10-2 ⋅cm, and was promising for electrical discharge machining.

Precipitation in Al-Li-Cu Alloys

1981 ◽  
Vol 39 ◽  
pp. 44-45
Author(s):  
J. E. O'Neal ◽  
K. K. Sankaran
Keyword(s):  
Electron Microscopy ◽  
Age Hardening ◽  
Precipitation Behavior ◽  
Zone Formation ◽  
Specific Strength ◽  
Hardening Behavior ◽  
Cu Alloys ◽  
High Specific Strength ◽  
Transmission Electron ◽  
Structural Applications

Al-Li-Cu alloys combine high specific strength and high specific modulus and are potential candidates for aircraft structural applications. As part of an effort to optimize Al-Li-Cu alloys for specific applications, precipitation in these alloys was studied for a range of compositions, and the mechanical behavior was correlated with the microstructures.Alloys with nominal compositions of Al-4Cu-2Li-0.2Zr, Al-2.5Cu-2.5Li-0.2Zr, and Al-l.5Cu-2.5Li-0.5Mn were argon-atomized into powder at solidification rates ≈ 103°C/s. Powders were consolidated into bar stock by vacuum pressing and extruding at 400°C. Alloy specimens were solution annealed at 530°C and aged at temperatures up to 250°C, and the resultant precipitation was studied by transmission electron microscopy (TEM).The low-temperature (≲100°C) precipitation behavior of the Al-4Cu-2Li-0.2Zr alloy is a combination of the separate precipitation behaviors of Al-Cu and Al-Li alloys. The age-hardening behavior at these temperatures is characteristic of Guinier-Preston (GP) zone formation, with additional strengthening resulting from the coherent precipitation of δ’ (Al3Li, Ll2 structure), the presence of which is revealed by the selected-area diffraction pattern (SADP) shown in Figure la.

Lattice imaging of precipitates in Al-Zn-Mg alloy

1986 ◽  
Vol 44 ◽  
pp. 412-413
Author(s):  
C. K. Wu
Keyword(s):  
Grain Boundaries ◽  
Homogeneous Nucleation ◽  
Alloy System ◽  
Mg Alloy ◽  
List Type ◽  
Lattice Structures ◽  
Type Number ◽  
Orientation Relationships ◽  
Lattice Imaging ◽  
The Matrix

The precipitation phenomenon in Al-Zn-Mg alloy is quite interesting and complicated and can be described in the following categories:(i) heterogeneous nucleation at grain boundaries;(ii) precipitate-free-zones (PFZ) adjacent to the grain boundaries;(iii) homogeneous nucleation of snherical G.P. zones, n' and n phases inside the grains. The spherical G.P. zones are coherent with the matrix, whereas the n' and n phases are incoherent. It is noticed that n' and n phases exhibit plate-like morpholoay with several orientation relationship with the matrix. The high resolution lattice imaging techninue of TEM is then applied to study precipitates in this alloy system. It reveals the characteristics of lattice structures of each phase and the orientation relationships with the matrix.

The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

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