scholarly journals Microstructural Study of Arc Beads in Aluminum Alloy Wires with an Overcurrent Fault

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4133
Author(s):  
Xueyan Xu ◽  
Zhijin Yu ◽  
Yang Li ◽  
Weifeng Wang ◽  
Lan Xu
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundaries ◽  
Second Phase ◽  
Aluminum Wire ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Metallographic Structure ◽  
Average Grain Size ◽  
Composition Segregation ◽  
Electrical Faults

To clarify the understanding and analysis of arc molten marks in electrical faults of aluminum alloy wires, this paper simulates overcurrent faults of aluminum alloy wires at currents of 128 A–224 A and uses thermogravimetry-differential scanning calorimetry (TG-DSC), optical microscopy (OM), scanning electron microscope (SEM) and X-ray energy spectroscopy (EDS) to characterize the effects of current on the microstructure of arc beads. The results show that there are small and large amounts of Al-Si and Al-Fe binary phases in the metallographic structure of the aluminum alloy wires at the rated current, the grains are fine, and there are no significant grain boundaries. After an overcurrent fault occurs in the wires, a high-temperature arc causes the second phase in the aluminum alloy to disappear, a cellular dendritic metallographic structure appears, the grain boundaries become more well-defined, and composition segregation occurs at the grain boundaries. Using the Image-Pro-Plus software to quantify the grain characteristics, the average grain size is found to gradually decrease as the current increases. In addition, by comparing and analyzing the characteristics of arc beads in aluminum wires and aluminum alloy wires under the same conditions, alloying elements are found to have a refining effect on the grain boundaries, and there are coarse precipitates at the grain boundaries in the aluminum wire arc beads.

Continuous and Discontinuous Recrystallization of 6013 Aluminum Alloy

2013 ◽  
Vol 753 ◽  
pp. 221-224 ◽  
Author(s):  
Krzysztof Sztwiertnia ◽  
Magdalena Bieda ◽  
Anna Korneva
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundaries ◽  
Second Phase ◽  
Sheet Plane ◽  
Temperature Range ◽  
Orientation Mapping ◽  
Second Phase Particles ◽  
The Matrix ◽  
Continuous Recrystallization

In situ orientation mapping using TEM and calorimetric measurements were carried out to investigate the annealing behavior of cold-rolled 6013 aluminum alloy. The recrystallization of the material can be considered to be a number of processes that correspond to two separate stored energy release peaks. In the temperature range of the peak 1, the deformation zones around the large second-phase particles acted as sites for particle-stimulated nucleation. In the matrix, at the same time, some elongation of grains occurred. The elongated matrix grains appeared because of the reduction of the dislocation density and the annihilation of some low-angle grain boundaries between chains of subgrains lying in layers parallel to the sheet plane. The matrix processes in this temperatures range can be considered forms of continuous recrystallization. The matrix high-angle grain boundaries started to migrate at the temperature range of the peak 2. They moved mostly in the direction normal to the sheet plane. Heating of the sample for an appropriate time at those temperatures resulted in the complete discontinuous recrystallization of the material. The recrystallized microstructure was dominated now by elongated grains, which were a few times thicker than those obtained by annealing at the temperatures of the peak 1.

Influence of Annealing Time on Microstructure of Ni-W Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 613-618
Author(s):  
Qiao Zhang ◽  
Shu Hua Liang ◽  
Chen Zhang ◽  
Jun Tao Zou
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Grain Size ◽  
Grain Boundaries ◽  
Annealing Time ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size ◽  
Scanning Electron

The as-cast Ni-W alloys with 15wt%W, 25wt%W and 30wt%W were annealed in hydrogen at 1100. The effect of the annealing time on the microstructure of Ni-W alloys was studied, and the phase constituents and microstructure of annealed Ni-W alloys were characterized by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that no any phase changed for Ni-15%W, Ni-25%W and Ni-30%W alloys annealed for 60 min, 90 min and 150 min, which were still consisted of single-phase Ni (W) solid solution. However, microstructure had a significant change after annealing. With increase of annealing time, the microstructure of Ni-15%W alloy became more uniform after annealing for 90 min, and the average grain size was 95μm, whereas the grain size of Ni-15%W alloy increased significantly after annealing for 150 min. For Ni-25%W and Ni-30%W, there was no obvious change on the grain size with increase of annealing time, and the amount of oxides at grain boundaries gradually reduced. After annealing for 150 min, the impurities at grain boundaries almost disappeared. Subsequently, the annealing at 1100 for 150 min was beneficial for the desired microstructure of Ni-25%W and Ni-30%W alloys.

Chemically disordered Ni3Al synthesized by high vacuum evaporation

1991 ◽  
Vol 6 (10) ◽  
pp. 2019-2021 ◽  
Author(s):  
S.R. Harris ◽  
D.H. Pearson ◽  
C.M. Garland ◽  
B. Fultz
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
High Vacuum ◽  
Liquid Nitrogen Temperature ◽  
Vacuum Evaporation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size

Films of chemically disordered fcc Ni3Al were synthesized by the vacuum evaporation of Ni3Al onto room temperature and liquid nitrogen temperature substrates. X-ray diffractometry and transmission electron microscopy showed the material to be single phase with an average grain size of about 4 nm. The formation of the equilibrium L12 ordered phase occurred simultaneously with grain growth at temperatures above 350°C. Differential scanning calorimetry provided ordering enthalpies of 7 kJ/mole and 9 kJ/mole for material evaporated onto room temperature and liquid nitrogen temperature substrates, respectively.

Simulation of Damage Percolation Within Aluminum Alloy Sheet

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
O. S. Orlov ◽  
M. J. Worswick ◽  
E. Maire ◽  
D. J. Lloyd
Keyword(s):  
Aluminum Alloy ◽  
Void Nucleation ◽  
Phase Particle ◽  
Three Dimensional ◽  
Alloy Sheet ◽  
Void Coalescence ◽  
Second Phase ◽  
X Ray ◽  
Damage Initiation

A combined experimental and analytical approach is used to study damage initiation and evolution in three-dimensional second phase particle fields. A three-dimensional formulation of a damage percolation model is developed to predict damage nucleation and propagation through random-clustered second phase particle fields. The proposed approach is capable of capturing the three-dimensional character of damage phenomena and the three stages of ductile fracture, namely, void nucleation, growth, and coalescence, at the level of discrete particles. An in situ tensile test with X-ray tomography is utilized to quantify material damage during deformation in terms of the number of nucleated voids and porosity. The results of this experiment are used for both the development of a clustering-sensitive nucleation criterion and the validation of the damage percolation predictions. The evolution of damage in aluminum alloy AA5182 has been successfully predicted to match that in the in situ tensile specimen. Two forms of second phase particle field input data were considered: (1) that measured directly with X-ray tomography and (2) fields reconstructed statistically from two-dimensional orthogonal sections. It is demonstrated that the adoption of a cluster-sensitive void nucleation criterion, as opposed to a cluster-insensitive nucleation criterion, has a significant effect in promoting predicted void nucleation to occur within particle clusters. This behavior leads to confinement of void coalescence to within clusters for most of the duration of deformation followed by later development of a macrocrack through intracluster coalescence. The measured and reconstructed second phase particle fields lead to similar rates of predicted damage accumulation and can be used interchangeably in damage percolation simulations.

scholarly journals Kinetics of Austenite Grain Growth during a Continuous Heating of a Niobium Microalloyed Steel

2004 ◽  
Vol 467-470 ◽  
pp. 929-934 ◽  
Author(s):  
David San Martín ◽  
Francisca García Caballero ◽  
Carlos Capdevila ◽  
C. Carcía de Andrés
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Heating Rate ◽  
Grain Growth ◽  
Continuous Heating ◽  
Second Phase ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Average Grain Size ◽  
The Matrix

Grain growth is a thermally activated process in which the average grain size increases as temperature and time increases. The driving force for grain growth results from the decrease in the free energy associated with the reduction in total grain boundary energy. There are several known factors that influence the migration of grain boundaries such as second phase particles precipitated in the matrix and the solute elements segregated at grain boundaries. The austenite grain boundaries are revealed using the thermal etching method. Carbon extraction replicas were prepared to determine the composition and size of precipitates present in the matrix. In this work, the evolution of the average prior austenite grain size (PAGS) of a low carbon steel microalloyed with niobium is studied as a function of temperature and heating rate. Austenite grains show a two-stage growth. It has been found that as heating rate increases, the grain coarsening temperature (TGC) increases and the grain size at that temperature decreases. TGC temperature lies around 40-60°C below the temperature for complete dissolution of carbonitrides (TDISS).

scholarly journals Thermal Stability of Cryomilled Al-Mg-Er Powders

2017 ◽  
Vol 2017 ◽  
pp. 1-17
Author(s):  
Bamidele Akinrinlola ◽  
Raynald Gauvin ◽  
Carl Blais ◽  
Mathieu Brochu
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Second Phase ◽  
Scanning Calorimetry ◽  
Abnormal Growth ◽  
Average Grain Size ◽  
Electron Microscopy Analysis ◽  
Impurity Drag ◽  
Grain Boundary Motion ◽  
Thermal Stability Of

In this study, the thermal stability of nanostructured Al-Mg alloy powders was investigated. Two alloy compositions, Al-5Mg-0.1Er and Al-5Mg-0.5Er (wt.%), were cryogenically milled for 30 h to produce nanostructured powders. The microstructure of the milled powders with increasing temperature was investigated by differential scanning calorimetry (DSC) with one-hour annealing performed at selected temperatures followed by X-ray diffraction (XRD) and electron microscopy analysis. Prolonged milling led to significant oxygen pick-up in the powders. The Al-5Mg-0.1Er powders experienced grain growth typical of cryomilled Al-Mg powders, while the Al-5Mg-0.5Er alloy showed improved thermal stability. An average grain size of ~20 nm was observed up to 400°C (~0.8Tm) in the Al-5Mg-0.5Er powders, and abnormal growth at 550°C resulted in a maximum observed grain size of 234 nm. Thermal stability in the Al-Mg-Er powders is attributed to the combined effects of solute/impurity drag and second-phase pinning (nanoscale oxides, nitrides, and oxynitrides) that impede grain boundary motion.

The Microstructural Evolution of AA6111 Aluminum Alloy during Homogenization Treatment

2013 ◽  
Vol 749 ◽  
pp. 223-228 ◽  
Author(s):  
Shi Jiao Zhang ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Xi Wu Li ◽  
Feng Wang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Intermetallic Phases ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Homogenization Treatment ◽  
X Ray ◽  
Transmission Electron ◽  
Eutectic Morphology ◽  
Scanning Electron

The microstructures of AA6111 automotive aluminum alloy were investigated by optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and transmission electron microscope (TEM). The results indicated that as-cast AA6111 alloy has a complex microstructure. There were many kinds of intermetallic phases, such as lath-shaped β-Al5FeSi, Al15(FeMn)3Si2and Mg2Si on the grain boundaries. The Al5Cu2Mg8Si6precipitates presented non-equilibrium eutectic morphology in the grain interiors. After homogenization treatment (6h at 470), the low melting point Mg2Si phase began dissolving. The eutectic Al5Cu2Mg8Si6phase were dissolved completely after 530/24h homogenization treatment. The Al15(FeMn)3Si2phase started to be spheroidized at 560. Increasing treatment temperature will promote Mn to substitute for Fe in this phase.

scholarly journals Hydrolysis-Based Hydrogen Generation Investigation of Aluminum System Adding Low-Melting Metals

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1433
Author(s):  
Zeng Gao ◽  
Fei Ji ◽  
Dongfeng Cheng ◽  
Congxin Yin ◽  
Jitai Niu ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Hydrogen Production ◽  
Hydrogen Generation ◽  
Production Capacity ◽  
Graphite Crucible ◽  
Production Performance ◽  
Second Phase ◽  
Hydrogen Energy ◽  
Reaction Products ◽  
Scanning Calorimetry

In this age of human civilization, there is a need for more efficient, cleaner, and renewable energy as opposed to that provided by nonrenewable sources such as coal and oil. In this sense, hydrogen energy has been proven to be a better choice. In this paper, a portable graphite crucible metal smelting furnace was used to prepare ten multi-element aluminum alloy ingots with different components. The microstructure and phase composition of the ingots and reaction products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The reaction was carried out in a constant temperature water bath furnace at 60 °C, and the hydrogen production performance of the multi-element aluminum alloys in different proportions was compared by the drainage gas collection method. The experimental results show that the as-cast microstructure of Al–Ga–In–Sn aluminum alloy is composed of a solid solution of Al and part of Ga, and a second phase of In3Sn. After the hydrolysis reaction, the products were dried at 150 °C and then analyzed by XRD. The products were mainly composed of AlOOH and In3Sn. Alloys with different compositions react at the same hydrolysis temperature, and the hydrogen production performance is related to the ratio of low-melting-point metal elements. By comparing two different ratios of Ga–In–Sn (GIS), the hydrogen production capacity and production rate when the ratio is 6:3:1 are generally higher than those when the ratio is 7:2:1. The second phase content affects the hydrogen production performance.

scholarly journals Superplastic Behavioral Characteristics of Fine-Grained 5A70 Aluminum Alloy

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 62 ◽  
Author(s):  
Sheng Li ◽  
Zhongguo Huang ◽  
Shunyao Jin
Keyword(s):  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Energy Dispersive Spectrometer ◽  
Rate Sensitivity ◽  
Alloy Sheet ◽  
Second Phase ◽  
Fine Grained ◽  
Transmission Electron ◽  
Average Grain Size ◽  
The Matrix

A fine-grained 5A70 alloy sheet was obtained through a combination of rolling and heat treatment, with a total deformation reduction of 90% and an average grain size of 8.48 μm. The alloy was studied at 400, 450, 500, and 550 °C and exhibited excellent elongation-to-failures of 205, 321, 398, and 437% with coefficients for the strain rate sensitivity of 0.42, 0.40, 0.47 and 0.46, respectively. Electron backscatter diffraction (EBSD) results revealed that the massive grain boundaries were high angle boundaries, suggesting that boundary sliding and grain rotation occurred during superplastic deformation. The X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) results indicated that the compositions were the Al6(MnFe) and Mg-rich phase particles of the deformed 5A70 alloy. In addition, the weakening of the pinning effect led to abnormal grain growth at 500 and 550 °C, resulting in strain hardening. Transmission electron microscopy (TEM) examinations demonstrated that the applied stress at the head of the precipitated particles and/or grain boundaries exceeded the matrix-structure-promoted cavity nucleation. Cavities grew, interlinked, and coalesced, which resulted in crack formation that eventually led to superplastic fractures. Filaments formed at the fracture surfaces because of second phase precipitation at grain boundaries and the formation of Mg-rich oxides.

scholarly journals Synthesis and Characterization of Ba0.96Sr0.04Ce0.7Zr0.3O3 Solid Oxide Fuel Cell Electrolyte by Citrate EDTA Complexing Sol-Gel Process

2016 ◽  
Vol 71 ◽  
pp. 1-10 ◽  
Author(s):  
Jampana Madhuri Sailaja ◽  
Nandigam Murali ◽  
K. Samatha ◽  
V. Veeraiah
Keyword(s):  
Phase Formation ◽  
Fourier Transforms ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Second Phase ◽  
X Ray ◽  
Average Grain Size ◽  
Sol Gel Process ◽  
Sintered Powder ◽  
Infrared Spectrometer

This paper reports on the effect of Strontium doping on BaCe0.7Zr0.3O3electrolyte prepared using the citrate-EDTA complexing sol-gel process at temperature T=1000°C. The phase formation and evolution with the temperature has been studied by X-ray diffraction (XRD), thermal analysis (TG-DTA).The morphology of the sintered powder at T=1300°C are examined by SEM - Scanning Electron MicroscopyEDAX - Energy-dispersive X-ray spectroscopy analysisFTIR - Fourier transforms infrared spectrometer FTRS-Raman measurementsThe crystallite size of the ceramic powders calculated from Scherrer equation is 28nm and the diffraction peak shifted to higher angles. Microstructure of the sintered powder revealed that the average grain size is in the range of 2mm. The incorporation of Sr is found to suppress the formation of CeO2like second phase and enhance the grain growth in sintered oxides. Dense ceramic materials were obtained at 1300°C and the relative density is 80% of the theoretical density. FTIR and Raman measurements reveal the complete single phase formation of the orthorhombic perovskite structure. The ionic conductivity of the pellet is investigated from room temperature to 400°C and is found to be 1.1x10-4S/cm (400°C). The conductivity increased as temperature increases and the activation energies is 0.48eV and hence this composition qualifies to be a promising electrolyte.

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