scholarly journals Effect of multiple forging on the microstructure and properties of an as-cast Cu–Ni–Si alloy with high Ni and Si contents

2021 ◽  
Author(s):  
Jinlong Zhang ◽  
Zhenlin Lu ◽  
Lei Jia ◽  
Hui Xie ◽  
Xin Wei ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Grain Boundaries ◽  
Phase Changes ◽  
Casting Method ◽  
Ageing Treatment ◽  
Microstructure And Properties ◽  
Equiaxed Grains ◽  
Solution Matrix

Abstract A Cu–Ni–Si alloy with high Ni and Si contents was prepared by the traditional melting and casting method, and then multiple forging and ageing were conducted to investigate their effect on the microstructure and properties. The results show that reticular Ni31Si12 phases are located on the grain boundaries of the dendritic α-Cu(Ni,Si) solution matrix in the as-cast Cu–Ni–Si alloy because of the high Ni and Si contents, and some rice-like Ni2Si phases precipitate in the interior of α-Cu(Ni,Si) grains during cooling. With increasing number of forging passes, the morphology of the α-Cu(Ni,Si) matrix changes from dendrites to elongated dendrites and then equiaxed grains, the Ni31Si12 phase changes from reticular to irregular and then particle-like, while the Ni2Si phase gradually disappears. As a result, the hardness increases continuously up to 18 forging passes, while the electrical conductivity first increases and then decreases significantly. The hardness and electrical conductivity achieve the highest values with 18 forging passes and a subsequent ageing treatment at 450 °C for 4 h, and the corresponding microstructure comprises an equiaxed α-Cu(Ni,Si) matrix with microscale Ni31Si12 particles and sub-microscale Ni2Si precipitates.

THE EFFECT OF RRA ON THE MICROSTRUCTURE AND PROPERTIES OF A NOVEL Al-Zn-Mg-Cu-Zr ALLOY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 900-905 ◽  
Author(s):  
XIWU LI ◽  
BAIQING XIONG ◽  
YONGAN ZHANG ◽  
BAOHONG ZHU ◽  
HONGWEI LIU ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Yield Strength ◽  
Mechanical Strength ◽  
Grain Boundaries ◽  
Tensile Yield Strength ◽  
Lower Range ◽  
Microstructure And Properties ◽  
Zr Alloy

A novel Al -7.5 Zn -1.6 Mg -1.4 Cu -0.12 Zr alloy was subjected to the retrogression and re-ageing (RRA) treatments at a lower range of retrogression temperatures from 170 to 200°C. The effect of RRA on the mechanical properties, electrical conductivity and the microstructure of the alloy has been investigated. The results indicate that an increase in the yield strength of the alloy can be achieved after RRA treatment. With increase of the retrogression temperature, the retrogression time for keeping the strength levels similar to T6 temper decreases rapidly. When submitted to RRA at 170°C for 90-120 min, the alloy can obtain a good performance on both SCC and mechanical strength; the electrical conductivity was above 40%IACS, reaching values typical for T76 condition and the tensile yield strength values were 552-570 MPa which is higher than that of the T6 temper. The microstructure is a very fine distribution of GP zones and η′ precipitates inside grains, similar to T6 condition and η precipitates on grain boundaries distributed similarly to T7 temper.

Microstructure and Texture Evolution in Nickel during Accumulative Roll Bonding

2016 ◽  
Vol 879 ◽  
pp. 454-458 ◽  
Author(s):  
Jia Qi Duan ◽  
Md Zakaria Quadir ◽  
Michael Ferry
Keyword(s):  
Grain Boundaries ◽  
Accumulative Roll Bonding ◽  
Texture Evolution ◽  
Shear Bands ◽  
Rolling Direction ◽  
Sample Surface ◽  
Deformation Texture ◽  
Roll Bonding ◽  
Equiaxed Grains ◽  
Electron Back Scattered Diffraction

Microstructure and texture evolution of commercially pure Ni processed by accumulative roll-bonding (ARB) up to eight cycles were studied using electron back scattered diffraction (EBSD). During ARB processing, the original coarse equiaxed grains were gradually transformed into refined lamellar grains along the rolling direction (RD). Shear bands started forming after three cycles. The fraction of low angle grain boundaries (LAGBs) increased after the first and second cycle because of orientation spreading within the original grains. However, their fraction decreased with the evolution of high angle grain boundaries (HAGBs) during subsequent deformations, until saturation was reached after six cycles. Overall, the typical deformation texture components (S, Copper and Brass) were enhanced up to six ARB cycles and then only Copper was further strengthened. At higher cycles a higher Copper concentration was found near sample surface than the interiors due to a high frictional shear of ARB processing.

Effect of Heat Treatment on Microstructure and Properties of Cu-3Ti-1Al Alloy

2013 ◽  
Vol 749 ◽  
pp. 282-286
Author(s):  
Xian Hui Wang ◽  
Xiao Chun Sun ◽  
Xiao Hong Yang ◽  
Shu Hua Liang
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Electrical Conductivity ◽  
Electron Microscope ◽  
Treatment Process ◽  
Intermetallic Phase ◽  
Strengthening Effect ◽  
Microstructure And Properties ◽  
Optimal Heat Treatment ◽  
Transmission Electron

The effect of heat treatment on the microstructure and properties of Cu-3Ti-1Al alloy was investigated. The microstructure was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the hardness and electrical conductivity were tested as well. The results showed that the hardness and electrical conductivity of Cu-3Ti-1Al alloy increased significantly after solid solution and ageing treatment. The strengthening effect of Cu-3Ti-1Al alloy was attributed to the formation of intermetallic phase such as Ti3Al and fine precipitates of coherent β-Cu4Ti. With increase of the aging time and the temperature, the precipitates became coarse and incoherent with Cu matrix, and the discontinuous precipitate β started to grow from grain boundaries toward grain interior, which decreased hardness. As the formation of Ti3Al, β-Cu3Ti and β-Cu4Ti phase can efficiently reduce Ti concentration in Cu matrix. The electrical conductivity of Cu-3Ti-1Al alloy increases. In the range of experiments, the optimal heat treatment process for Cu-3Ti-1Al alloy is solid solution at 850°C for 4h and ageing 500°C for 2h, and the hardness and electrical conductivity are 227HV and 12.3%IACS, respectively.

Effect of Aging Treatment on Mechanical Properties and Electrical Conductivity of Cu-5.7%Cr In Situ Composite Produced by Equal Channel Angular Pressing

2012 ◽  
Vol 560-561 ◽  
pp. 344-348 ◽  
Author(s):  
Wei Wei ◽  
Kun Xia Wei ◽  
Igor V. Alexandrov ◽  
Qing Bo Du ◽  
Jing Hu
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Equal Channel Angular Pressing ◽  
Aging Treatment ◽  
In Situ Composite ◽  
Angular Pressing ◽  
Peak Aging ◽  
Average Size ◽  
Equiaxed Grains

The effect of aging treatment on mechanical properties and electrical conductivity of Cu-5.7%Cr in situ composite produced by equal channel angular pressing (ECAP) was investigated here. The rotation and spreading of Cr particles was observed in Cu-5.7%Cr alloy during the ECAP, resulting in long thin in situ filaments. The equiaxed grains of the Cu phase with an average size of 200 nm were developed after eight passes of ECAP. When aging at 400~450 °C for 1 h, Cu-5.7%Cr composite after ECAP shows the maximum microhardness, and the electrical conductivity is larger than 70% of IACS. At 400 °C, the peak aging time appears for 0.5~2 h, dependent on the pre-strain for all ECAP samples. With the increase of ECAP passes, the enhancement of tensile strength due to the aging treatment declines, and even shows negative after eight passes of ECAP. The combination of ECAP and aging treatment would be a promising process to balance mechanical properties and electrical conductivity of Cu-5.7%Cr composite.

Electron tunneling through grain boundaries in transparent conductive oxides and implications for electrical conductivity: the case of ZnO:Al thin films

2018 ◽  
Vol 5 (4) ◽  
pp. 715-726 ◽  
Author(s):  
Viet Huong Nguyen ◽  
Ulrich Gottlieb ◽  
Anthony Valla ◽  
Delfina Muñoz ◽  
Daniel Bellet ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Grain Boundaries ◽  
Electron Tunneling ◽  
Transparent Conductive Oxides ◽  
New Model ◽  
Polycrystalline Semiconductors

A new model is presented to describe charge scattering at grain boundaries in degenerately doped polycrystalline semiconductors such as transparent conductive oxides.

Effect the Ratio and Particle Size of Glass Powder from Fluorescent Tubes Waste on Electrical Properties of PVA-Glass Composites

2021 ◽  
Vol 19 (10) ◽  
pp. 106-114
Author(s):  
Hani M Hussien
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Dielectric Constant ◽  
Glass Powder ◽  
Dissipation Factor ◽  
Powder Particle Size ◽  
Casting Method ◽  
Glass Composites ◽  
Mixing Ratios ◽  
Solution Casting Method

The polymer composites used in the present study were made of polyvinyl alcohol (PVA) as a matrix and glass powder as a filler. The glass powder was obtained from fluorescent tubes waste. The solution casting method was used to fabricate PVA/glass powder composite. Three groups of samples were prepared. The first was prepared by using PVA with the addition of glass powder (sieved less than 20 μm) in proportions 10, 20, 30, 40, and 50 %. The second: the mixing ratios of PVA and glass powder were 80% and 20%, respectively. The third: The mixing ratios of PVA and glass powder were 60% and 40%, respectively. In Both previous groups, the added glass powder used was sieved with sizes less than 20, 45, 105, and 125 μm. For all samples, the following properties were measured at room temperature: DC electrical conductivity, dielectric constant, electrical conductivity, and dissipation factor. The last three properties were measured with a range of frequencies from 1kHz to 5MHz. DC conductivity increases with increasing of glass powder. It was found that the highest conductivity values are for samples composed of glass powder with a particle size of less than 45 μm for both ratios of glass 20% and 40%. It is also noticed that within most frequencies, the sample with 30% glass has the largest dissipation factor. At 20% filler of glass powder, it is noted that the highest values of the dielectric constant are for samples composed of glass powder with a particle size of less than 45 μm and 125 μm. Below 1 MHz, the effect of glass powder particle size on the AC conductivity is minimal. It is found that the samples containing glass powder (less than 125 μm and 105 μm), have similar and lowest dissipation factor. At 40% filler of glass powder, it is noted that the lowest values of the dielectric constant are for samples composed of glass powder with a particle size little than 105 μm.

scholarly journals Fabrication of Silk Fibroin/Graphene Film with High Electrical Conductivity and Humidity Sensitivity

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1774 ◽  
Author(s):  
Haoran Zhang ◽  
Juntao Zhao ◽  
Tieling Xing ◽  
Shenzhou Lu ◽  
Guoqiang Chen
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Silk Fibroin ◽  
Biomedical Applications ◽  
Wearable Sensors ◽  
Graphene Film ◽  
Natural Material ◽  
Casting Method ◽  
Good Biocompatibility ◽  
Minimum Resistance

Silk fibroin (SF) is a natural material with good biocompatibility and excellent mechanical properties, which are complementary to graphene with ultrahigh electrical conductivity. In this study, to maximally combine graphene and silk fibroin, a well-dispersed silk fibroin/graphene suspension was successfully prepared in a simple and effective way. Then we prepared a flexible conductive SF/graphene film with a minimum resistance of 72.1 ± 4.7 Ω/sq by the casting method. It was found that the electrical conductivity of the SF/graphene film was related to the water content of the film, and the variation was more than 200 times. Therefore, it will play an important role in the field of humidity sensors. It also has excellent mechanical properties in both wet and dry states. These unique features make this material a promising future in the fields of biomedical applications, wearable sensors, and implantable internal sensors.

scholarly journals Spatially Resolved Mapping of Electrical Conductivity across Individual Domain (Grain) Boundaries in Graphene

ACS Nano ◽  
2013 ◽  
Vol 7 (9) ◽  
pp. 7956-7966 ◽  
Author(s):  
Kendal W. Clark ◽  
X.-G. Zhang ◽  
Ivan V. Vlassiouk ◽  
Guowei He ◽  
Randall M. Feenstra ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Grain Boundaries ◽  
Spatially Resolved ◽  
Individual Domain

Effect of Mo doping on the microstructure and properties of an Fe36Ni Invar alloy

2020 ◽  
Vol 34 (31) ◽  
pp. 2050297
Author(s):  
Liming Dong ◽  
Zhaopeng Yu ◽  
Xianjun Hu ◽  
Fang Feng
Keyword(s):  
Grain Size ◽  
Thermal Expansion ◽  
Grain Boundaries ◽  
Coefficient Of Thermal Expansion ◽  
Solution Temperature ◽  
Microstructure And Properties ◽  
Invar Alloys ◽  
Average Grain Size ◽  
Mo Content ◽  
Hot Rolled

The effects of doping with different Mo contents on the microstructure and properties of Fe36Ni Invar alloys were investigated. The results show that when 0.9 wt.% Mo and 1.8 wt.% Mo were added to Fe36Ni, the tensile strengths of the hot rolled alloys were 46 and 61 MPa higher than that of the 0 wt.% Mo sample, respectively. With an increase in Mo content from 0.9 to 1.8 wt.%, the solution temperature of the highest hardness after heat treatment increased from 800[Formula: see text]C to 850[Formula: see text]C, respectively. The addition of 0.9 wt.% Mo refined the average grain size from 37 to 15 [Formula: see text]m, and an excessive amount of Mo (1.8 wt.%) did not refine the grains further. After Mo was added, the precipitates on the original grain boundaries changed into nanoprecipitates dispersed in the grain boundaries and inside the grains. Mo was present in the alloy in the form of a carbide and in solid solution, which affected the magnetic lattice effect and increased the thermal expansion coefficient of the alloy. However, upon comparing the samples doped with 0 wt.% Mo, 0.9 wt.% Mo and 1.8 wt.% Mo, it was found that the addition of 0.9 wt.% Mo not only refined the grain size and improved the mechanical properties of the alloy but also led to a low coefficient of thermal expansion (CTE) over the range from 20[Formula: see text]C to 300[Formula: see text]C.

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