scholarly journals Strategies to Achieve High Strength and Ductility of Pulsed Electrodeposited Nanocrystalline Co-Cu by Tuning the Deposition Parameters

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5194
Author(s):  
Killang Pratama ◽  
Christian Motz
Keyword(s):  
Tensile Strength ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Current ◽  
High Strength ◽  
Internal Stresses ◽  
Low Duty Cycle ◽  
Deposition Parameters ◽  
Pulse On Time ◽  
Strength And Ductility

Strategies to improve tensile strength and ductility of pulsed electrodeposited nanocrystalline Co-Cu were investigated. Parameters of deposition, which are pulse current density, duty cycle, and pulse-on time were adjusted to produce nanocrystalline Co-Cu deposits with different microstructures and morphologies. The most significant improvement of strength and ductility was observed at nanocrystalline Co-Cu deposited, at a low duty cycle (10%) and a low pulse-on time (0.3 ms), with a high pulse current density (1000 A/m2). Enhancement of ductility of nanocrystalline Co-Cu was also obtained through annealing at 200 °C, while annealing at 300 °C leads to strengthening of materials with reduction of ductility. In the as deposited state, tensile strength and ductility of nanocrystalline Co-Cu is strongly influenced by several factors such as concentration of Cu, grain size, and processing flaws (e.g., crystal growth border, porosity, and internal stresses), which can be controlled by adjusting the parameters of deposition. In addition, the presence of various microstructural features (e.g., spinodal and phase decomposition), as well as recovery processes induced by annealing treatments, also have a significant contribution to the tensile strength and ductility.

High Strength Titanium Rods Produced by Thermomechanical Powder Consolidation

2016 ◽  
Vol 861 ◽  
pp. 147-152
Author(s):  
Fei Yang ◽  
Brian Gabbitas ◽  
Ajit Singh ◽  
Chung Fu Wang
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Pure Titanium ◽  
Hot Extrusion ◽  
High Strength ◽  
Sintered Titanium ◽  
Vacuum Sintering ◽  
Powder Consolidation ◽  
Strength And Ductility

In this paper, pure titanium rods, with high strength and ductility, were prepared by vacuum sintering titanium powder compacts at 1300oC for 2h and then hot extruding the as-sintered titanium billets at 900oC in air. The microstructure and property changes, after vacuum sintering and hot extrusion, were investigated. The results showed clear evidence of porosity in the microstructure of as-sintered titanium billet and tensile testing of as-sintered material gave yield strength, ultimate tensile strength and ductility values of 570MPa, 602MPa and 4%, respectively. After extrusion at 900oC, no obvious pores could be seen in the microstructure of as-extruded titanium rod, and the mechanical properties were significantly improved. The yield strength, ultimate tensile strength and the ductility reached 650MPa, 705MPa and 20%, respectively, which are much higher than values for CP titanium (grade 4), with a yield strength of 480MPa, ultimate tensile strength of 550MPa and ductility of 15%. The fracture characteristics of as-sintered and as-extruded titanium rods have also been investigated.

scholarly journals Modulation of Multiple Precipitates for High Strength and Ductility in Al-Cu-Mn Alloy

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7383
Author(s):  
Linxiang Liu ◽  
Zhijun Wang ◽  
Qingfeng Wu ◽  
Zhongsheng Yang ◽  
Kexuan Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
High Strength ◽  
Mechanical Behaviors ◽  
High Tensile Strength ◽  
Transmission Electron ◽  
Evolution Pattern ◽  
Elongation To Failure ◽  
High Elongation ◽  
Strength And Ductility

The category and morphology of precipitates are essential factors in determining the mechanical behaviors of aluminum alloys. It is a great challenge to synthetically modulate multiple precipitates to simultaneously improve strength and ductility. In the present work, by optimizing the precipitations of the GP zone, θ’-approximant and θ’ phase for an Al-Cu-Mn alloy, a high tensile strength of 585 MPa with large elongation of 12.35% was achieved through pre-deformation and aging. The microstructure evolution pattern was revealed by detailed characterizations of scanning electron microscopy and transmission electron microscopy. It was found that such high tensile strength of the samples was due to a combination of strengthening by the high density of dispersive fine precipitates and dislocations, and the high elongation to failure was primarily attributed to the multimodal precipitates and elimination of precipitation-free zones along the grain boundaries. The strategy proposed here is a promising way of preparing ultra-strong Al-Cu-Mn alloys.

scholarly journals Electro-plastic metal cutting

2019 ◽  
Vol 75 (6) ◽  
pp. 735-740
Author(s):  
O. A. Troitskii ◽  
V. I. Stashenko
Keyword(s):  
Cast Iron ◽  
Friction Force ◽  
Current Density ◽  
Metal Cutting ◽  
Pulse Current ◽  
High Strength ◽  
Heating Zone ◽  
Current Density Vector ◽  
Plastic Metal ◽  
Density Vector

In the process of cutting of steels, high strength and heat-resistant alloys a strong warming-up of the cutting instrument takes place, necessitating its cooling by special emulsions and resulting in quick wear and increase of products cost. It was determined by experiment, that during a metal with current cutting, an electro-plastic effect arises. During the lector-plastic cutting, the plastic deformation of a metal under pulse current effect becomes easier, making the friction force between the metal chips and the cutting instrument front edge lower. The electro-plastic metal cutting method accounting the current polarity, current density vector directions, as well as pulse current parameters, can considerably improve the cut surface microstructure and increase the instrument service life. At that, the thermal regime of the cutting can be lowered due to cutting force lowering and heating zone shifting inside the piece or the instrument due to Thomson effect. It was shown, that during the electro-plastic metal cutting the friction force can decrease by 25–30% at the favorable current density vector orientation, as it takes place during electro-static metal drawing and rolling. The current plasticizing action results in decreasing friction force and the chips twisting radius, which can be confluent even for cast iron. At the example of metal drilling with the pulse current, the important current effects on the cutting mechanical parameters revealed. The conditions of metal electro-plastic cutting stated. Results of the experiment study of metal electro-plastic cutting quoted for the processes of steel and cast iron drilling.

Growth of Tunnels during Aluminum DC Pulse Current Etching

2014 ◽  
Vol 654 ◽  
pp. 24-30
Author(s):  
Dan Lu Liu ◽  
Ren Gui Xiao ◽  
Teng Zou ◽  
Jian Zhong Wang ◽  
Jian Xin Cao ◽  
...  
Keyword(s):  
Current Density ◽  
Duty Cycle ◽  
Growth Velocity ◽  
High Purity ◽  
Pulse Current ◽  
Aluminum Foil ◽  
Experimental Results ◽  
Surface Areas ◽  
High Purity Aluminum ◽  
First Time

High-purity aluminum foil was etched with DC pulse current in acids solutions at first time. Experiments indicated that tunnels morphology was influenced by current density, pulse duty-cycle and frequency of DC pulse current, tunnels began to grow when the current density reached to 0.8A cm-2, and tunnels grew along three directions to form a netlike construction in the surface of aluminum foil, which increased effectually surface areas of aluminum foil. In addition, when aluminum was etched in the solution of 1 N HCl +0.8 N HNO3,tunnels morphology shows that tunnel does not grow continually during DC pulse current etching, so it is a method to study the mechanism of tunnel growth, for example period of tunnel growth, velocity of tunnel growth. The experimental results are discussed according to tunnels morphology.

The Effect of Pulse Current on Microstructure and Mechanical Property of the Pure Aluminum

2014 ◽  
Vol 703 ◽  
pp. 119-123
Author(s):  
Yao Li ◽  
Shu Hua Peng ◽  
Jun Jie Yang
Keyword(s):  
Mechanical Property ◽  
Tensile Strength ◽  
Grain Boundary ◽  
Current Density ◽  
Pulse Current ◽  
Pure Aluminum ◽  
Boundary Part ◽  
Dislocation Cells ◽  
Microstructure And Mechanical Property ◽  
Dislocation Walls

The tensile experiments were carried out under the condition of different pulse current on pure aluminum to analyze the effect of pulse current on the mechanical property such as tensile strength and elongation on material. The results show that pulse current could improve the mechanical properties and with pulse current the elongation of the aluminum increased to 19.5% and its tensile strength drops to some extent with the increase of electricity. At the same time, the dislocation structure features under different current density are also different. Without pulse current, dislocation is distributed as group unevenly. But when the current density J=8×102A/cm2, dislocation morphology changed into a mass of dislocation cells and moved to the grain boundary. Part of the cell walls formed grain boundary and then small angle subgrain formed. With the increase of current density, dislocation walls are arranged neatly and parallel to each other and at last single dislocation wall will be split into two or more parallel dislocation walls and form structure of striped band.

MORPHOLOGICAL STUDY OF PULSE CURRENT ELECTRODEPOSITED Zn-Fe ALLOY

2008 ◽  
Vol 22 (18n19) ◽  
pp. 3023-3030 ◽  
Author(s):  
D. MOHAMMADYANI ◽  
M. HEYDARZADEH SOHI
Keyword(s):  
Corrosion Resistance ◽  
Current Density ◽  
Duty Cycle ◽  
Morphological Study ◽  
Pulse Current ◽  
The Other ◽  
Peak Current Density ◽  
Pure Zinc ◽  
Alkaline Bath ◽  
Fe Alloys

Zn - Fe alloy electroplated coatings have attracted industrial interest because of their significantly higher corrosion resistance in comparison to pure zinc deposits. In this study pulse currents was applied for electrodeposition of Zn - Fe alloys, using alkaline bath. SEM studies confirmed that pulse electrodeposits are quite dense and smooth. It was also shown that increasing of peak current density (PCD) and duty cycle in pulse electrodeposition coarsen the structure and increase irregularity of the surface. Increasing of the frequency, on the other hand, results in the formation of finer structure.

A Study of the Microstructure and Properties of Electroformed Ni-P Model Insert

2007 ◽  
Vol 364-366 ◽  
pp. 232-236 ◽  
Author(s):  
Shih Tsung Ke ◽  
Jeou Long Lee ◽  
Yih Min Yeh ◽  
Shuo Jen Lee ◽  
Ming Der Ger
Keyword(s):  
Internal Stress ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Current ◽  
Pulse Frequency ◽  
Cathodic Current ◽  
Peak Current Density ◽  
Peak Current ◽  
Ultrafine Grained ◽  
Nanostructure Material

In this study, a Ni-P alloy electroforming nanostructure material with low surface roughness and low internal stress was developed by using a pulse current. Square-wave cathodic current modulation was employed to electrodeposit ultrafine-grained Ni-P films from an additivefree Sulfamate nickel bath. The effect of various factors, such as peak current density, duty cycle and pulse frequency on the roughness and internal stress were investigated. Pulse current significantly influences the microstructure of Ni-P alloys. The internal stress and roughness of Ni-P alloys increased as peak current density increased, but the internal stress of Ni-P alloys decreased as duty cycle decreased.

An Investigation of Machining Time and Surface Roughness in Wire-EDM for Inconel 800

2015 ◽  
Vol 789-790 ◽  
pp. 20-24 ◽  
Author(s):  
P. Dutta ◽  
S.C. Panja ◽  
G.R.K. Sastry
Keyword(s):  
Surface Roughness ◽  
Pulse Current ◽  
High Strength ◽  
Pulsed Current ◽  
Machining Time ◽  
Temperature Exposure ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Harmful Effects ◽  
Inconel 800

This paper presents an experimental investigation on the influences of EDM parameters on machining time and surface roughness for machining Inconel 800.Inconel800is widely used in construction of equipment that must have high strength and resist carburization, oxidation and other harmful effects of high temperature exposure. The selected WEDM parameters are pulsed current (210,220 and 230A), pulse-on time (2,3.25, 4.5, 5.75, 7 and 8.25μs) and pulse-off time (19 and 46μs). It has been observed that surface roughness increases with the increase of pulse-on time and pulse current. Similarly machining time decreases with the increase of pulse current and pulse-on time. Conversely, a decreased value of pulsed current and pulse-on time results in a better surface finish and increased machining time.

scholarly journals Mechanical Properties of Carbon Fiber Reinforced Nanocrystalline Nickel Composite Electroforming Deposit

2019 ◽  
Vol 17 (1) ◽  
pp. 1466-1472
Author(s):  
Wanghuan Qian ◽  
Zhangyong Yu ◽  
Tao Zhang
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Room Temperature ◽  
Pulse Current ◽  
High Strength ◽  
Fiber Reinforced ◽  
Nanocrystalline Nickel ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Carbon Fiber Reinforced

AbstractIn order to obtain higher strength fiber reinforced composite electroforming deposit, carbon fiber reinforced nanocrystalline nickel composite electroforming deposit was prepared by electrodepositing with pulse current and a flexible wheel was applied to rub and extrude the electroforming deposit. Results shown that when the grains of the carbon fiber reinforced nickel composite electroforming deposit were refined from micron to 80nm at room temperature, the microhardness increased from 230Hv to 740Hv, and the tensile strength increased from 1025MPa to 1472MPa. With the further refinement of the grains of the electroforming deposit, the tensile strength decreased significantly due to the decrease of the bonding strength between the carbon fiber and the nickel matrix, while the microhardness still increased to 758Hv. At 200°C, the carbon fiber reinforced nanocrystalline nickel composite electroforming deposit still showed high strength. When the temperature rose to 400°C, the influence of nanocrystalline on the tensile strength of the carbon fiber reinforced nickel composite electroforming deposit was no longer significant, due to the rapid growth of crystal grains and the precipitation of interfacial brittle substances.

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