scholarly journals The Role of Electric Current-Associated Free Energy and Forced Convection on Grain Refinement in Pure Aluminum under Electropulsing

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3846
Author(s):  
Ning Li ◽  
Limin Zhang ◽  
Rong Zhang ◽  
Pengfei Yin ◽  
Hongjing Wu ◽  
...  
Keyword(s):  
Free Energy ◽  
Electric Current ◽  
Grain Refinement ◽  
Forced Convection ◽  
Pure Aluminum ◽  
Side Wall ◽  
Metal Mesh ◽  
Dendrite Fragmentation ◽  
Equiaxed Grains ◽  
Convection Dominated

An experimental study with respect to the effect of an alternating electropulsing on grain refinement in pure aluminum was reported. The macrostructural observation with the mold preheated to different temperature and embedded the metal mesh indicated that the change of electric current-associated free energy related with the position of crystal nuclei (ΔGem) and forced convection dominated the generation of fine equiaxed grains (FEG). Under electropulsing with 480 A, ΔGem induced the dissociation of crystal nuclei from the upper interface of the electrode and the melt, leading to the generation of FEG. For a larger current intensity, FEG originated from the dissociation of crystal nuclei on the side wall besides the upper interface due to ΔGem and the forced convection. Furthermore, the model coupling the dissociation of crystal nuclei and dendrite fragmentation due to the forced convection and the dissociation of crystal nuclei due to ΔGem was presented to explain the formation mechanism of FEG in pure aluminum under electropulsing.

Innovative approaches in the organization of closed waste-free production of organic pork using cultural and natural agricultural land

2020 ◽  
pp. 15-25
Author(s):  
Volodymyr Ivanov ◽  
Andrii Onyshchenko ◽  
Liudmyla Ivanova ◽  
Liudmyla Zasukha ◽  
Valerii Hryhorenko
Keyword(s):  
Agricultural Land ◽  
Side Wall ◽  
Front Wall ◽  
Lower Edge ◽  
Metal Mesh ◽  
Two Phase ◽  
Transparent Plastic ◽  
Pork Production ◽  
Young Pigs ◽  
Side Walls

The mobile house for two-phase litter rearing piglets was developed in the conditions of pasture their housing, the feature of which is that its side walls and roof are made in the form of two similar in shape and length of arched panels. In the back wall of the inner shield is a litter box, a self-feeder for piglets, a feed unit for a sow and a wicket, and in the front wall of the outer shield are doors with a wicket. Along with this, all walls and the roof of the litter box are made of transparent plastic, and the wall located near the self-feeding trough is also made perforated. In addition, the lower edge of the side wall of the inner arch-shaped shield has slides in which the lower edge of the side wall of the outer arc-shaped shield is inserted. A house with transformable fences has been developed to rear the young pigs. The structural feature of the house is the presence on the outside of the walls of the bobbins with a metal mesh edged at the bottom with a flexible sleeve. In order to ensure the conditions of gentle etching of the vegetation cover and to prevent damage to the turf of the pasture, the house can be completed with another type of hedge consisting of two hinged sections with doors on each side of the fence. In addition, the horizontal wings are rigidly attached to the hedge and connected by a metal mesh around the perimeter, the size of the cells of which ensures that the grass is eaten but prevents the turf of the pasture from being undermined. The developed devices for camp-pasture and feeding of maternal stock, suckling pigs, weaning pigs, repair and fattening pigs are well suited for year-round closed non-waste organic pork production using cultural and natural agricultural land. Key words: housing, feeding, devices, sows, piglets, young animals, pasture, organic pork.

Grain refinement of pure aluminum by direct current pulsed magnetic field and inoculation

2014 ◽  
Vol 24 (5) ◽  
pp. 1295-1300 ◽  
Author(s):  
Hang CHEN ◽  
Jin-chuan JIE ◽  
Ying FU ◽  
Hong-jun MA ◽  
Ting-ju LI
Keyword(s):  
Magnetic Field ◽  
Grain Refinement ◽  
Direct Current ◽  
Pure Aluminum ◽  
Pulsed Magnetic Field

Grain Refinement and Hot Tearing of Aluminium Alloys - How to Optimise and Minimise

2009 ◽  
Vol 630 ◽  
pp. 213-221 ◽  
Author(s):  
Mark Easton ◽  
David H. StJohn ◽  
Lisa Sweet
Keyword(s):  
Grain Refinement ◽  
Aluminium Alloys ◽  
Hot Tearing ◽  
Key Factors ◽  
Grain Refiner ◽  
Factors Affecting ◽  
Equiaxed Grains

Grain refinement and hot tearing are important key factors affecting the quality of castings. There have been substantial advances in the understanding of both of these phenomena over the last two decades. The paper discusses strategies for obtaining the lowest cost grain refiner addition and provides an explanation for how the refinement of equiaxed grains leads to a reduction in hot tear susceptibility. However, it also provides a warning that adding more grain refiner may not be better for reducing hot tear susceptibility. Alloy factors affecting hot tearing are also discussed. Finally, a list of six key considerations is provided to help casthouse and foundry engineers when trying to optimise grain refinement and reduce hot tearing.

scholarly journals Formation of the Equiaxed Grains in Pure Aluminum and Al-0.2%Cu Alloy Ingots

1970 ◽  
Vol 34 (8) ◽  
pp. 802-807
Author(s):  
Akira Suzuki ◽  
Jitsuhito Nakamura ◽  
Toshimasa Sakamoto
Keyword(s):  
Pure Aluminum ◽  
Cu Alloy ◽  
Equiaxed Grains

Application of Different Conductive Substrate Materials for Heat Transfer Enhancement in Cooling of Electronic Components

2014 ◽  
Vol 1082 ◽  
pp. 327-331
Author(s):  
Thiago Antonini Alves ◽  
Murilo A. Barbur ◽  
Felipe Baptista Nishida
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Forced Convection ◽  
Pure Aluminum ◽  
Rectangular Channel ◽  
Electronic Components ◽  
Transfer Enhancement ◽  
Cooling Process ◽  
Conductive Substrate

In this research, a study of the heat transfer enhancement in electronic components mounted in channels was conducted by using different materials in the conductive substrate. In this context, a numerical analysis was performed to investigate the cooling of 3D protruding heaters mounted on the bottom wall (substrate) of a horizontal rectangular channel using the ANSYS/FluentTM 15.0 software. Three different materials of the conductive substrate were analyzed, polymethyl methacrylate (PMMA), fiberglass reinforced epoxy laminate (FR4), and pure aluminum (Al). Uniform heat generation rate was considered for the protruding heaters and the cooling process happened through a steady laminar airflow, with constant properties. The fluid flow velocity and temperature profiles were uniform at the channel entrance. For the adiabatic substrate, the cooling process occurred exclusively by forced convection. For the conductive substrate, the cooling process was characterized by conjugate forced convection-conduction heat transfer through two mechanisms; one directly between the heaters surfaces and the flow by forced convection, and the other through conduction at the interfaces heater-substrate in addition to forced convection from the substrate to the fluid flow at the substrate surface. The governing equations and boundary conditions were numerically solved through a coupled procedure using the Control Volumes Method in a single domain comprising the solid and fluid regions. Commonly used properties in cooling of electronics components mounted in a PCB and typical geometry dimensions were utilized in the results acquisition. Some examples were presented, indicating the dependence of the substrate thermal conductivity related to the Reynolds number on the heat transfer enhancement. Thus, resulting in a lower work temperature at the electronic components.

Influence of ECAP Routes on the Microstructure and Mechanical Properties of Hot Extruded 3003 Al Alloy

2007 ◽  
Vol 124-126 ◽  
pp. 1397-1400 ◽  
Author(s):  
Byoung Soo Lee ◽  
Hoon Cho
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Hot Extrusion ◽  
High Strength ◽  
Al Alloy ◽  
Deformation Structure ◽  
Ecap Processing ◽  
Fine Grained ◽  
Strain Process ◽  
Equiaxed Grains

The microstructures and mechanical properties of unidirectional deformation structured Al alloy during ECAP with various deformation routes were investigated. In order to fabricate unidirectional deformation structure for Al alloy, hot extrusion was carried out. It was found that the deformation route A in ECAP routes is the dominant route for the grain refinement and strengthening. In deformation route A, the high strength ultra-fine grained Al alloy with a grain size of ~ 200 nm was obtained due to the accumulation of consecutive strain process. In contrast, the strength of ECAP’ed Al alloy produced via deformation route C was greatly increased after one pass because the grains were strained and cancelled each pass. By contrast, the equiaxed grains were obtained in deformation route BC because the sample was rotated 90 O in the same sense in each pass. The deformation route BC was superior to the deformation route C because the deformation route BC was more favorable than the deformation route C in the accumulation of consecutive strain. It is also found that unidirectional deformation structured Al alloy via hot extrusion shows similar grain refinement tendency with equiaxed structured Al alloy during ECAP processing.

Microstructure and Texture Evolution in Metals and Alloys during Intense Plastic Deformation

2012 ◽  
Vol 715-716 ◽  
pp. 51-60 ◽  
Author(s):  
Alexandre P. Zhilyaev ◽  
Terry R. McNelley ◽  
Oscar A. Ruano
Keyword(s):  
Plastic Deformation ◽  
Grain Refinement ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Texture Evolution ◽  
Pure Aluminum ◽  
Liquid Nitrogen Temperature ◽  
Metals And Alloys ◽  
Work Piece ◽  
Friction Stir

ntense plastic deformation is generally effective in producing grain refinement. IPD methods include equal channel angular pressing/extrusion (ECAP/ECAE), high-pressure torsion (HPT), accumulative roll bonding (ARB), and friction stir processing (FSP), among others. In this work, we summarize the main results on grain refinement by these processing methods and present our own data on microstructure and texture evolution in metals and alloys during ECAP, HPT and FSP. Whereas ECAP and HPT are usually performed with the work piece material initially at room temperature or even at liquid nitrogen temperature to enhance refinement, FSP involves a brief but complex thermomechanical cycle with peak temperatures up to 0.7 0.9 TMelt. Apparently, materials undergo dynamic recrystallization (DRX) during FSP. DRX also occurs also in metals and alloys of low TMeltdue to adiabatic heating during HPT performed at room temperature. The paper is devoted to revisiting of previous as well as new results and a comparative analysis of microstructure and texture evolution in commercially pure aluminum and selected pure metals and alloys during ECAP, HPT and FSP in order to illustrate the limits of grain refinement.

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