scholarly journals Effects of Aging on the Microstructure and Properties of 7075 Al Sheets

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4022
Author(s):  
Zhongxin Zhao ◽  
Ruoqing Wu ◽  
Bo Wang ◽  
Mingchu Huang ◽  
Guopeng Lei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Treatment Time ◽  
Aging Treatment ◽  
Strength Properties ◽  
Double Aging ◽  
Transmission Electron ◽  
One Step ◽  
The One ◽  
Effects Of Aging ◽  
Working Efficiency

The effects of one-step aging and double aging on the properties and microstructures of 7075 Al sheets were studied via mechanical property testing, scanning electron microscopy, and transmission electron microscopy. The results indicated that with continued one-step aging, the tensile and yield strengths of the Al sheets first increased rapidly with an increase in the treatment time to 8 h and then increased slightly with a further increase in the treatment time to 10 h. The tensile and yield strengths became constant after 16 h of treatment. The mechanical strength properties of the Al sheets peaked after 16 h of one-step aging. However, the double aging treatment provided better mechanical properties and working efficiency than the one-step aging treatment. The tensile strength and microhardness resulting from double aging were greater than those resulting from one-step aging by 5.87% and 8.71%, respectively. Herein, we quantified the contribution ofvarious strengthening mechanisms.

scholarly journals Ionic Liquids-Containing Silica Microcapsules: A Potential Tunable Platform for Shaping-Up Epoxy-Based Composite Materials?

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 881
Author(s):  
Ting Shi ◽  
Sébastien Livi ◽  
Jannick Duchet ◽  
Jean-François Gérard
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Diameter Distribution ◽  
Excellent Thermal Stability ◽  
Transmission Electron ◽  
Micron Size ◽  
Phosphonium Ionic Liquid ◽  
One Step ◽  
The One ◽  
First Time

In this work, silica microcapsules containing phosphonium ionic liquid (IL), denoted SiO2@IL, were successfully synthesized for the first time using the one step sol-gel method in IL/H20 emulsion. The morphologies of the obtained micron-size microcapsules, including their diameter distribution, were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The thermal behavior of these microcapsules and the mass fraction of the encapsulated IL in the silica microcapsules were determined using thermogravimetric analysis, showing an excellent thermal stability (up to 220 °C) and highlighting that an amount of 20 wt.% of IL is contained in the silica microcapsules. In a second step, SiO2@IL microcapsules (1 wt.%) were dispersed into epoxy-amine networks to provide proof of concept of the ability of such microcapsules to act as healing agents as microcracks propagate into the epoxy networks.

Determination of Ascorbic Acid Based on a Platinum Nanoparticles Modified Au Electrode

2011 ◽  
Vol 110-116 ◽  
pp. 1732-1735
Author(s):  
Jia Hong He ◽  
Qiang Xu ◽  
Zhong Rong Song ◽  
Hai Yan Kuang
Keyword(s):  
Electron Microscopy ◽  
Ascorbic Acid ◽  
Modified Electrode ◽  
Platinum Nanoparticles ◽  
Reaction System ◽  
Au Electrode ◽  
Transmission Electron ◽  
Growth Method ◽  
One Step ◽  
The One

A Platinum nanoparticles modified Au electrode has been successfully fabricated by using an in situ growth method. In this method, the Platinum nanoparticles could be grown on the Au electrode surface via the one-step immersion into the mixture of H2PtCl6 (analytical grade, 1g/L), NaBH4 (analytical grade) and polyvinylpyrrolidone K30 (PVP, analytical grade). A certain amount of PVP was added into the reaction system to prevent the coagulation of the Platinum nanoparticles, which obtained by the chemical redox reaction of H2PtCl6 and NaBH4. The structures and morphologies of the Platinum nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) . The direct electrochemical behavior of ascorbic acid in 0.3 mol/L NaCl medium at the Platinum nanoparticles modified electrode has been investigated in detail. Compared to a bare Au electrode, a substantial decrease in the overvoltage of the ascorbic acid was observed at the Platinum nanoparticles modified electrode with oxidation starting at ca. 0.20 V vs. SCE (saturated KCl). At an applied potential of 0.18V, this modified electrode produced high and reproducible sensitivity to ascorbic acid and linear responses were obtained over a concentration range from 0.600 to 3.267 μmol/L with a detection limit of 1.9 nmol/L(S/N=3). The fabrication method of this sensor, which has highly sensitive, low working potential, and fast amperometric sensing to ascorbic acid, is simple and without using complex equipment. In addition, the sensor has been successfully used to detect ascorbic acid in real sample, thus is promising for the future development of ascorbic acid sensors.

scholarly journals Tuning the Morphology of ZnO Nanostructures with the Ultrasonic Spray Pyrolysis Process

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 569 ◽  
Author(s):  
Elif Emil ◽  
Gözde Alkan ◽  
Sebahattin Gurmen ◽  
Rebeka Rudolf ◽  
Darja Jenko ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Spray Pyrolysis ◽  
Ultrasonic Spray Pyrolysis ◽  
Ultrasonic Spray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Zno Particles ◽  
One Step ◽  
Spray Pyrolysis Process ◽  
The One

Nanostructured zinc oxide (ZnO) particles were synthesized by the one step Ultrasonic Spray Pyrolysis (USP) process from nitrate salt solution (Zn(NO3)2·6H2O). Various influential parameters, from Zn(NO3)2·6H2O concentrations (0.01875–0.0375 M) in the initial solution, carrier gas (N2) flow rates (0.5–0.75 L/min) to reaction temperature (400–800 °C), were tested to investigate their role on the final ZnO particles’ morphology. For this purpose, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM) and (Selected Area Electron Diffraction) SAED techniques were used to gain insight into how the ZnO morphology is dependent on the USP process. It was revealed that, by certain parameter selection, different ZnO morphology could be achieved, from spherical to sphere-like structures assembled by interwoven nanoplate and nanoplate ZnO particles. Further, a more detailed crystallographic investigation was performed by XRD and Williamson-Hall (W-H) analysis on the ZnO with unique and non-typical planar morphology that was not reported before by USP synthesis. Moreover, for the first time, a flexible USP formation model was proposed, ending up in various ZnO morphologies rather than only ideal spheres, which is highly promising to target a wide application area.

Determination of Ascorbic Acid Based on a Platinum Nanoparticles Modified Au Electrode

2013 ◽  
Vol 562-565 ◽  
pp. 813-816
Author(s):  
Jia Hong He ◽  
Zhi Qiang Gao ◽  
Zhong Rong Song
Keyword(s):  
Electron Microscopy ◽  
Ascorbic Acid ◽  
Modified Electrode ◽  
Platinum Nanoparticles ◽  
Reaction System ◽  
Au Electrode ◽  
Transmission Electron ◽  
Growth Method ◽  
One Step ◽  
The One

A Platinum nanoparticles modified Au electrode has been successfully fabricated by using an in situ growth method. In this method, the Platinum nanoparticles could be grown on the Au electrode surface via the one-step immersion into the mixture of H2PtCl6 (analytical grade, 1g/L), NaBH4 (analytical grade) and polyvinylpyrrolidone K30 (PVP, analytical grade). A certain amount of PVP was added into the reaction system to prevent the coagulation of the Platinum nanoparticles, which obtained by the chemical redox reaction of H2PtCl6 and NaBH4. The structures and morphologies of the Platinum nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) . The direct electrochemical behavior of ascorbic acid in 0.3 mol/L NaCl medium at the Platinum nanoparticles modified electrode has been investigated in detail. Compared to a bare Au electrode, a substantial decrease in the overvoltage of the ascorbic acid was observed at the Platinum nanoparticles modified electrode with oxidation starting at ca. 0.20 V vs. SCE (saturated KCl). At an applied potential of 0.18V, this modified electrode produced high and reproducible sensitivity to ascorbic acid and linear responses were obtained over a concentration range from 0.600 to 3.267 μmol/L with a detection limit of 1.9 nmol/L(S/N=3). The fabrication method of this sensor, which has highly sensitive, low working potential, and fast amperometric sensing to ascorbic acid, is simple and without using complex equipment. In addition, the sensor has been successfully used to detect ascorbic acid in real sample, thus is promising for the future development of ascorbic acid sensors.

Effect of Two-Step Aging Process on Microstructure and Fracture Toughness of 7085 Aluminum Alloy

2016 ◽  
Vol 852 ◽  
pp. 149-155
Author(s):  
Yang Song ◽  
Bai Qing Xiong ◽  
Yong An Zhang ◽  
Xi Wu Li ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Aging Process ◽  
Treatment Time ◽  
Aging Treatment ◽  
Free Zone ◽  
Intergranular Failure ◽  
Transmission Electron ◽  
Fracture Morphologies

In this paper, the effect of two-step aging treatment on microstructure and fracture toughness of 7085 aluminum alloy were investigated by using tear tests to carry out the fracture toughness tests of the alloy and using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to analyze the microstructure. The results showed the main precipitates in the alloy were GP zones and η' phases in the grains after 118°C/6h aging treatment. With further secondary aging treatment, grain boundaries precipitates (GBPs) grew up, and the precipitate-free zone (PFZ) showed up, the increasing proportion of intergranular failure was occurred and the fracture toughness decreased. With further prolonging of the secondary aging treatment time, precipitates in the grains tended to be coarser, the GBPs became discontinuous ,PFZ became wider, and there were decreasing proportion of the intergranular failure and increasing proportion of the transgranular failure showing on the fracture morphologies, the fracture toughness of 7085 aluminum alloy increased.

The Effects of Aging Treatment on the Strength and Conductivity of Cu-Ag-Zr-Co Alloy

2011 ◽  
Vol 695 ◽  
pp. 477-480
Author(s):  
Kyung Hun Park ◽  
Hoon Cho ◽  
Soong Keun Hyun
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Tensile Strength ◽  
Aging Treatment ◽  
High Strength ◽  
Development Trend ◽  
Coaxial Cable ◽  
High Electrical Conductivity ◽  
Transmission Electron ◽  
Effects Of Aging

The development trend for diagnostics is reducing the diameter of coaxial signal cables that comprise the probe cable. The thinner super-fine coaxial cable which is offering superior electronic and mechanical properties, such as 75 %IACS(International Annealed Copper Standard, electrical conductivity) and 700 ~ 800 MPa in tensile strength has to be developed. Cu-Ag based system is one of the most promising systems for high strength and high conductivity Cu alloys. In order to find the optimum conditions to obtain Cu-Ag-Zr-Co alloy with high strength and high electrical conductivity, the aging characteristics including work hardening of micro-Vickers hardness, tensile strength and electrical conductivity of this alloy were systematically measured at room temperature. Also the influence of aging treatment was investigated by transmission electron microscopy(TEM) and scanning electron microscopy(SEM) in this study. The aging treatment for precipitation was divided into two steps and carried out at various time and at different temperature and the multi-step aging treatment coupled with cold rolling was proposed for realizing Cu-Ag-Zr-Co alloys with high strength and high electrical conductivity. The electrical conductivity was improved from 31 %IACS to 91 %IACS remarkably and the tensile strength was increased from 230Mpa to 690Mpa greatly by an optimization of alloy composition and manufacturing process including aging.

scholarly journals Effects of Aging Treatment on Laser-Welded Mg-Rare Earth Alloy NZ30K

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Jun Dai ◽  
Li Yang ◽  
Lili Li ◽  
Guolin Guo ◽  
Lanzhong Guo
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Rare Earth ◽  
Supersaturated Solid Solution ◽  
Aging Treatment ◽  
Precipitation Sequence ◽  
Rare Earth Alloys ◽  
Rare Earth Alloy ◽  
Transmission Electron ◽  
Effects Of Aging

Magnesium-rare earth alloys have received extensive attention due to their attractive mechanical properties resulting from high density of precipitation. The precipitation sequence in laser-welded Mg-3Nd-0.2Zn-0.4Zr (NZ30K) alloy during aging treatment at 200°C and 225°C has been investigated using transmission electron microscopy (TEM). The results indicate that the tensile strength of laser-welded NZ30K can be improved significantly after aging treatment at 200°C for 8 h. It is found that the precipitation in laser-welded NZ30K alloy follows the sequence of supersaturated solid solution → β′′(DO19) → β′(fcc).

Encapsulation of Luminescent Quantum Nanodots in Polystyrene Nanocapsules by Microemulsion Polymerization

2005 ◽  
Vol 23 ◽  
pp. 19-22 ◽  
Author(s):  
Xiaotun Yang ◽  
Ning Huang ◽  
Yong Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Fluorescence Microscopy ◽  
Fluorescence Spectroscopy ◽  
Microemulsion Polymerization ◽  
Transmission Electron ◽  
One Step ◽  
The One ◽  
Polymerization Method

This paper reported on the one-step synthesis of polystyrene-quantum dots (PS@QD)nanoparticles using microemulsion polymerization method. The synthesized QD and PS@QD nanoparticles were characterized by UV, fluorescence spectroscopy, transmission electron microscopy (TEM) and fluorescence microscopy. The PS@QD is highly luminescent, which have the potential to be used as fluorescent probes in biological staining and diagnostics.

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

The Effect of Aging Heat Treatment on the Microstructure and Mechanical Properties of 10Cr20Ni25Mo1.5NbN Austenitic Steel

2016 ◽  
Vol 35 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Zhiyuan Liang ◽  
Wanhua Sha ◽  
Qinxin Zhao ◽  
Chongbin Wang ◽  
Jianyong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Austenitic Steel ◽  
Treatment Time ◽  
Aging Treatment ◽  
Secondary Phases ◽  
Aging Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
The Impact

AbstractThe effect of aging heat treatment on the microstructure and mechanical properties of 10Cr20Ni25Mo1.5NbN austenitic steel was investigated in this article. The microstructure was characterized by scanning electron microscopy, energy dispersive spectrometry and transmission electron microscopy. Results show that the microstructure of 10Cr20Ni25Mo1.5NbN austenitic is composed of austenite. This steel was strengthened by precipitates of secondary phases that were mainly M23C6 carbides and NbCrN nitrides. As aging treatment time increased, the tensile strength first rose (0–3,000 h) and then fell (3,000–5,000 h) due to the decrease of high density of dislocations. The impact absorbed energy decreased sharply, causing the sulfides to precipitate at the grain boundary. Therefore, the content of sulfur should be strictly controlled in the steelmaking process.

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