Pulsed Electric Current Sintering of Nano-Crystalline Iron-Base Powders

2007 ◽  
Vol 534-536 ◽  
pp. 589-592
Author(s):  
Yuan Yuan Li ◽  
Yan Long ◽  
Xiao Qiang Li ◽  
Yun Zhong Liu
Keyword(s):  
Electric Current ◽  
High Energy ◽  
Sintered Specimen ◽  
Iron Matrix ◽  
Crystalline Materials ◽  
Densification Temperature ◽  
Nano Crystalline ◽  
Average Grain Size ◽  
Pulsed Electric Current ◽  
Particulate Size

A new process of pulsed electric current sintering was developed. It combines compaction with activated sintering effectively and can manufacture bulky nano-crystalline materials very quickly. Pulsed electric current sintering of high-energy ball-milled nano-crystalline iron-based powders is investigated in this work. A nanostructured steel is obtained with high relative density and hardness by this process. The average grain size of iron matrix is 58nm and the carbide particulate size is less than 100nm. The densification temperature of ball-milled powders is approximately 200°C lower than that of blended powders. When the sintering temperature increases, the density of as-sintered specimen increases but the hardness of as-sintered specimen first increases and then decreases. Microstructure analysis results show that the decrease of hardness is caused by the dramatic grain growth of iron matrix.

scholarly journals Solid State Recycling of Aluminum Alloy Chips via Pulsed Electric Current Sintering

2020 ◽  
Vol 4 (1) ◽  
pp. 23
Author(s):  
Clemens Nikolaus Cislo ◽  
Bernhard Kronthaler ◽  
Bruno Buchmayr ◽  
Christian Weiß
Keyword(s):  
Solid State ◽  
Electric Current ◽  
Secondary Production ◽  
Energy Demand ◽  
Energy Savings ◽  
Processing Parameters ◽  
High Energy ◽  
Pulsed Electric Current ◽  
Positive Effect ◽  
Processing Steps

Based on high energy demand of the primary production and losses during secondary production, alternative recycling of aluminum becomes a popular research topic. Compared to both primary and secondary production of aluminum, solid state recycling offers energy savings and reduced material losses during processing by surpassing an inefficient melting step. In this work, a direct recycling route for machining chips via pulsed electric current sintering (PECS) is evaluated. Therefore, necessary processing steps for a complete recycling route are briefly outlined. After cleansing, EN AW 6082 chips, provided by Neuman Aluminium GmbH, Marktl, Austria, are compacted with variable loads and consolidated via PECS on two separate systems to enable a comparison. Produced specimens are examined with density measurements, optical microscopy and the bonding quality is evaluated by Vickers micro-hardness measurements. In combination with elevated temperature and deformation, applied current promotes consolidation amongst chips and improvements in density, hardness and microstructure are achieved. The results of this work clearly show a positive effect of PECS on the bonding amongst chips, but further research will be necessary to separate and understand influences of single processing parameters. Additionally, all processing steps from collection to consolidation have to be taken into account to achieve industrial implementation.

High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

1995 ◽  
Vol 53 ◽  
pp. 524-525
Author(s):  
Z. Horita ◽  
D. J. Smith ◽  
M. Furukawa ◽  
M. Nemoto ◽  
R. Z. Valiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Grain Boundaries ◽  
Energy State ◽  
High Energy ◽  
Grain Structure ◽  
Boundary Structure ◽  
Solid Solution Alloy ◽  
Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

Total scattering experiments on glass and crystalline materials at the ESRF on the ID11 Beamline

2014 ◽  
Vol 30 (S1) ◽  
pp. S2-S8 ◽  
Author(s):  
Andrea Bernasconi ◽  
Jonathan Wright ◽  
Nicholas Harker
Keyword(s):  
High Energy ◽  
Real Space ◽  
European Synchrotron Radiation Facility ◽  
Small Sample ◽  
Distribution Functions ◽  
Total Scattering ◽  
Crystalline Materials ◽  
Space Resolution ◽  
Atomic Pair ◽  
Counting Statistics

ID11 is a multi-purpose high-energy beamline at the European Synchrotron Radiation Facility (ESRF). Owing to the high-energy X-ray source (up to 140 keV) and flexible, high-precision sample mounting which allows small sample–detector distances to be achieved, experiments such as total scattering in transmission geometry are possible. This permits the exploration of a wide Q range and so provides high real-space resolution. A range of samples (glasses and crystalline powders) have been measured at 78 keV, first putting the detector as close as possible to the sample (~10 cm), and then moving it vertically and laterally with respect to the beam in order to have circular and quarter circle sections of diffraction rings, with consequent QMAX at the edge of the detector of about 16 and 28 Å−1, respectively. Data were integrated using FIT2D, and then normalized and corrected with PDFgetX3. Results have been compared to see the effects of Q-range and counting statistics on the atomic pair distribution functions of the different samples. A Q of at least 20 Å−1 was essential to have sufficient real-space resolution for both type of samples while statistics appeared more important for glass samples rather than for crystalline samples.

Sapphire/Nd:YAG composite by pulsed electric current bonding for high-average-power lasers

2018 ◽  
Vol 43 (13) ◽  
pp. 3065 ◽  
Author(s):  
Hiroaki Furuse ◽  
Yuki Koike ◽  
Ryo Yasuhara
Keyword(s):  
Electric Current ◽  
Average Power ◽  
High Average Power ◽  
Pulsed Electric Current

Pulsed Electric Current Sintered Cr2O3-rGO Composites

2016 ◽  
Vol 721 ◽  
pp. 419-424
Author(s):  
M. Erkin Cura ◽  
Vivek Kumar Singh ◽  
Panu Viitaharju ◽  
Joonas Lehtonen ◽  
Simo Pekka Hannula
Keyword(s):  
Fracture Toughness ◽  
Graphene Oxide ◽  
Electric Current ◽  
Chromium Oxide ◽  
High Hardness ◽  
High Wear Resistance ◽  
Carbide Formation ◽  
Indentation Fracture ◽  
Pulsed Electric Current ◽  
Indentation Fracture Toughness

Chromium oxide is a promising material for applications where excellent corrosion resistance, high hardness, and high wear resistance are needed. However, its use is limited because of low fracture toughness. Improvement of fracture toughness of chromium oxide while maintaining its afore mentioned key properties is therefore of high interest. In this communication we study the possibility of increasing the toughness of pulsed electric current sintered (PECS) chromium oxide by the addition of graphene oxide (GO). The indentation fracture toughness was improved markedly with the addition of graphene oxide. Materials prepared by direct chemical homogenization had better fracture toughness. In composites with 10 vol.% GO piling of thin graphene oxide layers resulted in the formation of graphite layers between Cr2O3 and in carbide formation, which were observed to be the main reasons for the degradation of the mechanical properties. The distribution of graphene oxide was more homogeneous, when the GO amount was 0.1 vol.% and the formation of graphitic layers were avoided due to lesser amount of GO as well as ultrasonic treatment following the ball milling.

Sign in / Sign up

Export Citation Format

Share Document