Influence of Reheating Profile on Microstructural Evolution of 2024 Al Wrought Alloy for Thixoextrusion

2007 ◽  
Vol 544-545 ◽  
pp. 371-374
Author(s):  
Dong In Jang ◽  
Young Ok Yoon ◽  
Hyung Ho Jo ◽  
Shae K. Kim
Keyword(s):  
Grain Size ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
Low Energy ◽  
Billet Temperature ◽  
High Productivity ◽  
Main Emphasis ◽  
Average Grain Size ◽  
Low Energy Consumption ◽  
Holding Temperature

Thixoextrusion, one of the thixoforming processes, has advantages of high productivity, reduction of the extrusion pressure and cost saving because of the low energy consumption compared with the conventional extrusion processes. For the thixoextrusion, the low liquid fraction (fL<0.3) should be achieved and also the liquid fraction and average grain size should be uniform according to the reheating profile at the desired low liquid fraction. The main emphasis of this study is to investigate the feasibility of thixoextrusion for 2024 Al wrought alloy without additional pretreatment. The results show that the liquid fraction and average grain size were almost uniform with respect to isothermal holding temperature and time. It was very useful for thixoextrusion in terms of process control such as billet temperature control and actual extrusion time.

Microstructural Control of 7075 Al Wrought Alloys through Thixoextrusion Route

2006 ◽  
Vol 510-511 ◽  
pp. 362-365 ◽  
Author(s):  
Young Ok Yoon ◽  
Hyung Ho Jo ◽  
Jin Kyu Lee ◽  
Dong In Jang ◽  
Shae K. Kim
Keyword(s):  
Grain Size ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
High Strength ◽  
Industrial Applications ◽  
High Productivity ◽  
Die Life ◽  
Average Grain Size ◽  
Low Energy Consumption ◽  
Holding Temperature

Thixoextrusion, one of the thixoforming processes, has advantages of high productivity, reduction of the extrusion pressure, extension of the die life, and cost saving owing to its low energy consumption compared with the conventional extrusion processes. Especially, thixoextrusion process is expected to be very effective for hard-to-form materials with high strength. The present study focuses on 7075 Al wrought alloy to investigate the potential industrial applications of the thixoextrusion process. The microstructural evolution of 7075 Al wrought alloy for thixoextrusion was investigated with respect to isothermal holding temperature and time in the partially remelted semisolid state. The results showed that the liquid fraction increased with increasing isothermal holding temperature and time while the average grain size was inversely proportional to isothermal holding temperature and time up to 5min. However, there was no big change of liquid fraction and average grain size with respect to isothermal holding temperature and time. The important fact that the liquid fraction and average grain size were almost uniform after 5 min holding time is considered very useful for thixoextrusion in terms of process control.

Microstructural Evolution of AZ31 Mg Wrought Alloy during Partial Remelting for Thixoextrusion

2006 ◽  
Vol 116-117 ◽  
pp. 251-254
Author(s):  
Young Ok Yoon ◽  
Shae K. Kim
Keyword(s):  
Grain Size ◽  
Microstructural Evolution ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
Holding Time ◽  
Interesting Point ◽  
Grain Sizes ◽  
Partial Remelting ◽  
Average Grain Size ◽  
Holding Temperature

An attempt has been made to investigate feasibility of thixoextrusion for AZ31 Mg wrought alloy through simple partial remelting. Microstructural evolution of AZ31 Mg wrought alloy for thixoextrusion was investigated as functions of isothermal holding temperature and time in the partially remelted semisolid state. The interesting point of this study was that the thixotropic structures of AZ31 Mg wrought alloy without additional pretreatment could be obtained through simple partial remelting. The uniform average grain size and liquid fraction according to the isothermal holding time were very important for the thixoextrusion. Because, it is must be considered on actual extrusion time. The liquid fraction was increased with increasing isothermal holding temperature and time. But, the liquid fraction was almost uniform after 10 min. The average grain size was decreased with increasing isothermal holding temperature. On the other hand, as the holding time increased, the average grain sizes were uniform at 615 and 622. This phenomenon is very useful for thixoextrusion in terms of process control such as actual extrusion time.

Effect of Partial Remelting Procedure on the Microstructural Evolution of 7075 Al Wrought Alloy for Thixoextrusion

2006 ◽  
Vol 116-117 ◽  
pp. 336-339 ◽  
Author(s):  
Hyung Ho Jo ◽  
Young Ok Yoon ◽  
Jin Kyu Lee ◽  
Shae K. Kim
Keyword(s):  
Grain Size ◽  
Feasibility Study ◽  
Microstructural Evolution ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
Holding Time ◽  
Interesting Point ◽  
Partial Remelting ◽  
Average Grain Size ◽  
Holding Temperature

The feasibility study for thixoextrusion of 7075 Al wrought alloys was carried out with respect to reheating profile, isothermal holding temperature and time during the partial remelting through simple partial remelting. The reheating rates were 40/min and 60/min. The isothermal holding temperatures were controlled at 609, 622, 628 and 632 for 0, 2, 5, 10 and 30 min. The interesting point of this study was that the thixotropic structures of 7075 Al wrought alloy without additional pretreatment could be obtained through simple partial remelting. The average grain size was significantly smaller in the quickly heated specimen. The liquid fraction was increased with increasing isothermal holding temperature and time while the average grain size was inversely proportional to isothermal holding temperature and time. However, there was no big change of liquid fraction and average grain size with respect to isothermal holding time. The important fact that the liquid fraction and average grain size were almost uniform after 5 min is considered very useful for thixoextrusion in terms of actual extrusion time.

Bubble Electrospinning and Bubble-Spun Nanofibers

2020 ◽  
Vol 14 (1) ◽  
pp. 10-13 ◽  
Author(s):  
Lynn Y. Wan
Keyword(s):  
Surface Tension ◽  
Low Energy ◽  
Efficient Technology ◽  
High Productivity ◽  
Needleless Electrospinning ◽  
Polymeric Nanofibers ◽  
Low Energy Consumption ◽  
Potential Applications ◽  
Surface Morphologies ◽  
Unique Surface

Electrospinning is a highly efficient technology for fabrication of a wide variety of polymeric nanofibers. However, the development of traditional needle-based electrospinning has been hampered by its low productivity and need of tedious work dealing with needles cleaning, installation and uninstallation. As one of the most promising needleless electrospinning means, bubble electrospinning is known for its advantages of high productivity and relatively low energy consumption due to the introduction of a third force, air flow, as a major force overcoming the surface tension. In this paper, the restrictions of conventional electrospinning and the advantages of needleless electrospinning, especially the bubble electrospinning were elaborated. Reports and patents on bubble-spun nanofibers with unique surface morphologies were also reviewed in respect of their potential applications.

Microstructure Evolution and Coarsening Mechanism of 7075 Semi-Solid Aluminum Alloy Pre-Deformed by ECAP Method

2016 ◽  
Vol 256 ◽  
pp. 294-300 ◽  
Author(s):  
Jin Long Fu ◽  
Yu Wei Wang ◽  
Kai Kun Wang ◽  
Xiao Wei Li
Keyword(s):  
Aluminum Alloy ◽  
Solid State ◽  
Ostwald Ripening ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
Angular Pressing ◽  
Average Grain Size ◽  
Semi Solid ◽  
Equiaxed Grains ◽  
Kinetics Of

To investigate the influence of refined grains on the microstructure of 7075 aluminum alloy in semi-solid state, a new strain induced melting activation (SIMA) method was put forward containing two main stages: pre-deformation with equal channel angular pressing (ECAP) method and isothermally holding in the semi-solid temperature range. The breaking up and growth mechanisms of the grains and kinetics of equiaxed grains coarsening during the semi-solid holding were investigated. The results showed that the average grain size after ECAP extrusion decreased significantly, e.g., microstructure with average globular diameter less than 5μm was achieved after four-pass ECAP extrusion. Obvious grain coarsening had been found during isothermal holding in the semi-solid state and the roundness of the grains increased with the increasing holding time. The proper microstructure of 66.8μm in diameter and 1.22 in shape factor was obtained under proper soaking condition (at 590°C for 15 min). Two coarsening mechanisms, namely, coalescence in lower liquid fraction and Ostwald ripening in higher liquid fraction contributed to the grain growth process.

Nanostructure Evolution of ZnO in Ultra-fast Microwave Sintering

2011 ◽  
Vol 691 ◽  
pp. 65-71 ◽  
Author(s):  
Rodolfo F. K. Gunnewiek ◽  
Ruth Herta Goldsmith Aliaga Kiminami
Keyword(s):  
Grain Size ◽  
Zinc Oxide ◽  
Grain Growth ◽  
Microwave Sintering ◽  
High Heating Rate ◽  
Heating Rates ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Holding Temperature

Grain growth is inevitable in the sintering of pure nanopowder zinc oxide. Sintering depend on diffusion kinetics, thus this growth could be controlled by ultra-fast sintering techniques, as microwave sintering. The purpose of this work was to investigate the nanostructural evolution of zinc oxide nanopowder compacts (average grain size of 80 nm) subjected to ultra-rapid microwave sintering at a constant holding temperature of 900°C, applying different heating rates and temperature holding times. Fine dense microstructures were obtained, with controlled grain growth (grain size from 200 to 450nm at high heating rate) when compared to those obtained by conventional sintering (grain size around 1.13µm), which leads to excessively large average final grain sizes.

scholarly journals Study of Stannous-Cerium Oxide Nanocomposites as Nanofilm, Nanodot and Nanorod

2013 ◽  
Vol 19 ◽  
pp. 69-79
Author(s):  
Narender Budhiraja ◽  
Ashwani Sharma ◽  
Sanjay Kumar ◽  
Anupreet Kaur ◽  
N.V. Unikrishnan
Keyword(s):  
Grain Size ◽  
Cerium Oxide ◽  
Glass Substrate ◽  
Nanocomposite Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrd Diffraction ◽  
Main Emphasis ◽  
Average Grain Size ◽  
Rolling Method

In the present paper, main emphasis is given to synthesize the Stannous-Cerium oxide nanocomposites in nanofilms, nanodots and nanorods by Chemical bath method, Chemical drop method and Chemical rolling Method. These nanocomposite materials are synthesized on a glass substrate at 100 °C temperature. Crystallography investigation of these materials is done by X-ray diffraction (XRD) which reveals that average grain size is 58.9 nm and 62.3 nm for nanofilms and nanodots on glass substrate respectively whereas XRD diffraction for nanorod on glass substrate reveals that material is amorphous in nature.

scholarly journals Low energy intensity production of fuel-grade bio-butanol enabled by membrane-based extraction

2020 ◽  
Vol 13 (12) ◽  
pp. 4862-4871
Author(s):  
Ji Hoon Kim ◽  
Marcus Cook ◽  
Ludmila Peeva ◽  
Jet Yeo ◽  
Leslie W. Bolton ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Intensity ◽  
Low Energy ◽  
Biodiesel Production ◽  
Extraction System ◽  
High Productivity ◽  
Low Energy Consumption

Innovative membrane-based extraction system tailoring affinity-driven separation enables continuous biodiesel production with high productivity and low energy consumption.

Microstructural Evolution of ZL104 Aluminum Alloy Semi-Solid Billet Fabricated by RAP Process

2019 ◽  
Vol 285 ◽  
pp. 234-239
Author(s):  
Yong Fei Wang ◽  
Sheng Dun Zhao ◽  
Chao Chen ◽  
Peng Dong ◽  
Peng Zhang
Keyword(s):  
Aluminum Alloy ◽  
Ostwald Ripening ◽  
Isothermal Holding ◽  
Isothermal Treatment ◽  
Liquid Droplets ◽  
Microstructural Coarsening ◽  
Average Grain Size ◽  
Cold Rolled ◽  
Semi Solid ◽  
Holding Temperature

In this study, ZL104 aluminum alloy supplied in cold rolled state was introduced in recrystallization and partial melting (RAP) process to fabricate semi-solid billets. During the RAP process, samples cut from cold rolled ZL104 aluminum plate were heated to different semi-solid temperatures, and the effects of isothermal treatment parameters on the microstructures of semi-solid billets were investigated. Results showed that, with the increase of isothermal holding temperature and time, both the average grain size and the shape factor were increased. Namely, the shape of solid grain was more and more spherical, but the size of solid grain was larger and larger, which may be not suitable for semi-solid forming. The size of liquid droplets was increased while the number of liquid droplets was decreased with increasing the isothermal holding temperature and time. Microstructural coarsening of solid grain were attributed to coalescence and Ostwald ripening mechanisms, however, the latter one played a more and more important role with the increase of isothermal holding time and temperature. Additionally, The optimal isothermal holding temperature and time are 570 °C and 5 min, respectively, and the coarsening rate constant is 1357.2 μm3/s at 570 °C.

Development of Thixoextrusion Process for 7000 Series Al Wrought Alloys

2006 ◽  
Vol 116-117 ◽  
pp. 771-774 ◽  
Author(s):  
Young Ok Yoon ◽  
Hyung Ho Jo ◽  
Jin Kyu Lee ◽  
Dong In Jang ◽  
Shae K. Kim
Keyword(s):  
Liquid Fraction ◽  
Isothermal Holding ◽  
Semisolid State ◽  
Grain Sizes ◽  
Partial Remelting ◽  
Different Content ◽  
Hardness Values ◽  
Holding Temperature

Thixoextrusion for 7003 and 7075 Al wrought alloys with different content of Cu was carried out with respect to isothermal holding temperature in the partially remelted semisolid state. Especially, despite higher extrudability index of 7075 Al wrought alloy compared with the extrudability index of 7003 Al wrought alloy, the maximum extrusion pressures of 7075 Al wrought alloy were about the same as the maximum extrusion pressures of 7003 Al wrought alloy at temperature with the liquid fraction 10% (7003-624, 7075-609). The hardness values of thixoextruded specimens were higher than that of as-quenched specimens only after partial remelting. The microstructures of thixoextruded specimens did not show any dendrites or rosette-like structures. The average grain sizes of thixoextruded specimens were smaller than average grain sizes of homogenized specimens.

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