scholarly journals Effect of Gradient Energy Density on the Microstructure and Mechanical Properties of Ti6Al4V Fabricated by Selective Electron Beam Additive Manufacture

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1509 ◽  
Author(s):  
Ta-I Hsu ◽  
Yu-Ting Jhong ◽  
Meng-Hsiu Tsai
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Energy Density ◽  
High Energy ◽  
High Energy Density ◽  
Positive Effects ◽  
Microstructure And Mechanical Properties ◽  
Gradient Energy

Selective Electron Beam Additive Manufacturing (SEBAM) is a promising powder bed fusion additive manufacturing technique for titanium alloys that select particular area melting in different energy density for producing complexly shaped biomedical devices. For most commercial Ti6Al4V porous medical devices, the gradient energy density is usually applied to manufacture in one component during the SEBAM process which selects different energy density built on particular zones. This paper presents gradient energy density base characterization study on an SEBAM built rectangular specimen with a size of 3 mm × 20 mm × 60 mm. The specimen was divided into three zones were built in gradient energy density from 16 to 26.5 J/mm3. The microstructure and mechanical properties were investigated by means of scanning electron microscopy, X-ray diffraction, transmission electron microscopy and mechanical test. The α′ martensitic and lack of fusion were observed in the low energy density (LED) built zone. However, no α′ phase and no irregular pores were observed both in overlap energy density (OED) and high energy density (HED) built zones located at the middle and bottom of the specimen respectively. This implies the top location and lower energy density have positive effects on the cooling rate but negative effects on densification. The subsequence mechanical properties result also supports this point. Moreover, the intermetallic Ti3Al found in the bottom may be due to the heat transfer from the following melting layer. Furthermore, the microstructure evolution in gradient energy built zones is discussed based on the findings of the microstructure and thermal history correlation analysis.

X-ray spectroscopy and spectropolarimetry of high energy density plasma complemented by LLNL electron beam ion trap experiments

2003 ◽  
Vol 74 (3) ◽  
pp. 1947-1950 ◽  
Author(s):  
A. S. Shlyaptseva ◽  
D. A. Fedin ◽  
S. M. Hamasha ◽  
S. B. Hansen ◽  
C. Harris ◽  
...  
Keyword(s):  
Electron Beam ◽  
Energy Density ◽  
Ion Trap ◽  
High Energy ◽  
High Energy Density ◽  
X Ray ◽  
Electron Beam Ion Trap ◽  
Density Plasma

Porosity Analysis in Metal Additive Manufacturing by Micro-CT

2018 ◽  
Author(s):  
Subin Shrestha ◽  
Thomas Starr ◽  
Kevin Chou
Keyword(s):  
Additive Manufacturing ◽  
Energy Density ◽  
Pore Formation ◽  
Total Pore Volume ◽  
High Energy ◽  
High Energy Density ◽  
Process Conditions ◽  
Micro Ct ◽  
Ct Scanner ◽  
Porosity Level

This study aims at analyzing process-induced pores in selective laser melting (SLM), a laser powder-bed fusion additive manufacturing (AM) process. Porosity is one of the most problematic defects in SLM parts; it impairs the part performance, and yet, is sharply sensitive to the parameters of the SLM process itself. Detailed analysis of SLM pore formations using a computed tomography (CT) technique is desired in order to understand the porosity level under different process conditions. In this study, an SLM system was used to fabricate samples, using Ti-6Al-4V powder, with single tracks formed, at 60 μm layer thickness, with different laser powers and scanning speeds to vary the energy density. A micro-CT (μ-CT) scanner was used to measure the internal features of the SLM specimens without any post-build treatments and to analyze the porosity inside single tracks formed with different energy densities. There are different mechanisms of pore formation in SLM, in particular, this study first focuses on the pore formation due to the keyhole phenomenon, caused by a high energy density. μ-CT scanning at a 6 μm resolution is able to clearly reveal the pores in the SLM samples. From the CT scan and analysis results, it is observed that increasing the energy density increases the volume of pores. For example, with 195 W and 200 mm/s, the number of pores is 93 and the total pore volume is 0.014 mm3 for a scanning length of 12 mm. On the other hand, if the energy density is less than 0.24 J/mm, few or no pores were observed, because possibly the melting process changes from the keyhole mode to the conduction mode.

Microstructure and mechanical properties of low-carbon steel fabricated by electron-beam additive manufacturing

2021 ◽  
Vol 11 (4) ◽  
pp. 427-432
Author(s):  
Elena Astafurova ◽  
Evgeny Melnikov ◽  
Sergey Astafurov ◽  
Marina Panchenko ◽  
Kseniya Reunova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Microstructure And Mechanical Properties

Nonrelativistic electron beam expansion in the solar corona/wind  and their type III radio bursts observed with LOFAR

2021 ◽  
Author(s):  
Hamish Reid ◽  
Eduard Kontar
Keyword(s):  
Electron Beam ◽  
Energy Density ◽  
Solar Corona ◽  
Electron Beams ◽  
Low Frequency ◽  
High Energy ◽  
High Energy Density ◽  
Moderate Intensity ◽  
Radio Bursts ◽  
Type Iii

<div> <div><span>Solar type III radio bursts contain a wealth of information about the dynamics of near-relativistic electron beams in the solar corona and the inner heliosphere; this information is currently unobtainable through other means.  Whilst electron beams expand along their trajectory, the motion of different regions of an electron beam (front, middle, and back) had never been systematically analysed before.  Using LOw Frequency ARray (LOFAR) observations between 30-70 MHz of type III radio bursts, and kinetic simulations of electron beams producing derived type III radio brightness temperatures, we explored the expansion as electrons propagate away from the Sun.  From relatively moderate intensity type III bursts, we found mean electron beam speeds for the front, middle and back of 0.2, 0.17 and 0.15 c, respectively.  Simulations demonstrated that the electron beam energy density, controlled by the initial beam density and energy distribution have a significant effect on the beam speeds, with high energy density beams reaching front and back velocities of 0.7 and 0.35 c, respectively.  Both observations and simulations found that higher inferred velocities correlated with shorter FWHM durations of radio emission at individual frequencies.  Our radial predictions of electron beam speed and expansion can be tested by the upcoming in situ electron beam measurements made by Solar Orbiter and Parker Solar Probe.</span></div> </div>

scholarly journals Hydrothermal Synthesis of Co-Doped NiSe2 Nanowire for High-Performance Asymmetric Supercapacitors

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1468 ◽  
Author(s):  
Yun Gu ◽  
Le-Qing Fan ◽  
Jian-Ling Huang ◽  
Cheng-Long Geng ◽  
Jian-Ming Lin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Energy Density ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Electrode Materials ◽  
Nickel Foam ◽  
High Energy ◽  
High Energy Density ◽  
Asymmetric Supercapacitor

Co@NiSe2 electrode materials were synthesized via a simple hydrothermal method by using nickel foam in situ as the backbone and subsequently characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and a specific surface area analyzer. Results show that the Co@NiSe2 electrode exhibits a nanowire structure and grows uniformly on the nickel foam base. These features make the electrode show a relatively high specific surface area and electrical conductivity, and thus exhibit excellent electrochemical performance. The obtained electrode has a high specific capacitance of 3167.6 F·g−1 at a current density of 1 A·g−1. To enlarge the potential window and increase the energy density, an asymmetric supercapacitor was assembled by using a Co@NiSe2 electrode and activated carbon acting as positive and negative electrodes, respectively. The prepared asymmetrical supercapacitor functions stably under the potential window of 0–1.6 V. The asymmetric supercapacitor can deliver a high energy density of 50.0 Wh·kg−1 at a power density of 779.0 W·kg−1. Moreover, the prepared asymmetric supercapacitor exhibits a good rate performance and cycle stability.

Non-Isothermal Resistance Heating for Hot-Stamped Parts with Tailored Properties and Tempering Treatment on Directly Hot-Stamped Parts

2014 ◽  
Vol 936 ◽  
pp. 1830-1835
Author(s):  
Cai Na Sun ◽  
Heng Hua Zhang
Keyword(s):  
Mechanical Properties ◽  
Energy Density ◽  
Heating Temperature ◽  
Hot Stamping ◽  
High Energy ◽  
High Energy Density ◽  
Boron Steel ◽  
Carbide Formation ◽  
Resistance Heating ◽  
Tempering Treatment

Non-isothermal resistance heating in the hot stamping of quenchable steel sheets was developed to produce ultra-high strength steel formed parts with tailored properties. The heating temperature of parts is related with width of samples heated by resistance heating. With the same input energy, the strength in the narrow portions is high owing to the high energy density and that in the wide portions is low owing to the low energy density. Hat-shaped products having a tensile strength arrange from 600 MPA to 1800 MPa were formed. The tempering treatment on the directly hot-stamped boron steel resulted in better mechanical properties and higher formability index. The SEM figures indicates that the nano-carbide formation during the tempering treatment were suggested as the evident reasons for the occurrence of the mentioned robust properties. Finally the combination of temperature 250 ℃ and holding time 45 min can achieve the best comprehensive mechanical properties.

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