scholarly journals Directed Light Fabrication of Iron-Based Materials

1995 ◽  
Vol 397 ◽  
Author(s):  
D.J. Thoma ◽  
C. Charbon ◽  
G.K. Lewis ◽  
R.B. Nemec
Keyword(s):  
Microstructural Development ◽  
Solid Model ◽  
Metal Powders ◽  
Solidification Behavior ◽  
Cooling Rates ◽  
3 Dimensional ◽  
Rapid Fabrication ◽  
Near Net Shape ◽  
Iron Based ◽  
Focal Zone

ABSTRACTDirected light fabrication (DLP) is a rapid fabrication process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, near-net shape, 3-dimensional metal components from a computer generated solid model. This study used iron-based alloys to evaluate the microstructural development in the DLF process. Continuous microstructural features are evident, implying a continuous liquid/solid interface during processing. In addition, solidification cooling rates have been determined based upon secondary dendrite arm spacings in Fe-25wt.%Ni and 316 stainless steel. Cooling rates vary from 101-105 K s-1, and the solidification behavior has been simulated using macroscopic heat transfer analyses.

scholarly journals Free-Form Processing of Near-Net Shapes Using Directed Light Fabrication

1998 ◽  
Author(s):  
D.J. Thoma ◽  
G.K. Lewis ◽  
J.O. Milewski ◽  
R.B. Nemec
Keyword(s):  
Free Form ◽  
Microstructural Development ◽  
Metal Powders ◽  
3 Dimensional ◽  
Form Processing ◽  
Rapid Fabrication ◽  
Near Net Shape ◽  
Thermomechanical Processes ◽  
Model Computer ◽  
Thermal Spray Processes

Abstract Directed light fabrication (DLF) is a rapid fabrication process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, near-net shape, 3- dimensional metal components from a computer generated solid model. Computer controls dictate the metal deposition pathways, and no preforms or molds are required to generate complex sample geometries with accurate and precise tolerances. The DLF technique offers unique advantages over conventional thermomechanical processes or thermal spray processes in that many labor and equipment intensive steps can be avoided to produce components with fully dense microstructures. Moreover, owing to the flexibility in power distributions of lasers, a variety of materials have been processed, ranging from aluminum alloys to tungsten, and including intermetallics such as MO5Si3. Since DLF processing offers unique capabilities and advantages for the rapid fabrication of complex metal components, an examination of the microstructural development has been performed in order to define and optimize the processed materials. Solidification studies of DLF processing have demonstrated that a continuous liquid/solid interface is maintained while achieving high constant cooling rates that can be varied between 10 to 105 Ks-1 and solidification growth rates ranging up to 10-2 ms-1.

scholarly journals Free Form Fabrication of Metallic Components Using the Directed Light Fabrication Process

1998 ◽  
Author(s):  
G.K. Lewis ◽  
J.O. Milewski ◽  
R.B. Nemec ◽  
D.B. Thoma
Keyword(s):  
Metal Forming ◽  
Free Form ◽  
Motion Path ◽  
Full Density ◽  
Solid Model ◽  
Free Standing ◽  
3 Dimensional ◽  
Processed Material ◽  
Near Net Shape ◽  
Focal Zone

Abstract The Directed Light Fabrication (DLF) process uses a laser beam and metal powder, fed into the laser focal zone, to produce free-standing metal components that are fully dense and have structural properties equivalent to conventional metal forming processes. The motion of the laser focal zone is precisely controlled by a motion path produced from a 3-dimensional solid model of a desired component. The motion path commands move the focal zone of the laser such that all solid areas of the part are deposited and the part can be built (deposited) in its entirety to near net shape, typically within +/-0.13mm. The process is applicable to any metal or intermetallic. Full density and mechanical properties equivalent to conventionally processed material are achieved.

scholarly journals An Intelligent Manufacturing Advisor for Casting and Injection-Moulding Based on a Mid-Surface Approach

2002 ◽  
Author(s):  
Helen L. Lockett ◽  
Marin D. Guenov
Keyword(s):  
Injection Moulding ◽  
Feature Recognition ◽  
Intelligent Manufacturing ◽  
Solid Model ◽  
Surface Approach ◽  
Knowledge Based ◽  
Solid Geometry ◽  
Near Net Shape ◽  
Manufacturing Features

Products that are manufactured using near net-shape manufacturing processes must be designed with regard to the constraints of the manufacturing process. The purpose of this research project is to develop a knowledge based manufacturing advisor to assist designers of products for casting and injection moulding. The manufacturing advisor is tightly integrated with a CAD solid modeller, and uses a novel feature recognition approach to identify the manufacturing features of the part. A mid-surface abstraction from the part’s solid geometry is used as the basis for feature recognition, and it is argued that this is a better approach to feature recognition for this class of parts than a CAD solid model. Initial testing indicates that the feature recognition process is able to effectively recognise a range of features but that the quality of the feature recognition is dependent on the mid-surface representation that is generated.

scholarly journals Effects of Titanium and Boron Additions with Cooling Rates on Solidification Behavior in Aluminum Alloys for Automotive Applications

2016 ◽  
Vol 57 (2) ◽  
pp. 193-200 ◽  
Author(s):  
JaeHwang Kim ◽  
DongHoon Nam ◽  
HooDam Lee ◽  
KyungMoon Lee ◽  
TaeGyu Lee ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Automotive Applications ◽  
Solidification Behavior ◽  
Cooling Rates

scholarly journals The 3-Dimensional Fermi Liquid Description for the Iron-Based Superconductors

2017 ◽  
Vol 190 (1-2) ◽  
pp. 45-66 ◽  
Author(s):  
Setsuo Misawa
Keyword(s):  
Fermi Liquid ◽  
Fermi Liquids ◽  
Electronic Specific Heat ◽  
Superconducting Transition ◽  
Iron Based Superconductors ◽  
Fermi Surfaces ◽  
3 Dimensional ◽  
Quasiparticle Energy ◽  
Iron Based ◽  
Specific Heat Coefficient

Abstract The quasiparticles in the normal state of iron-based superconductors have been shown to behave universally as a 3-dimensional Fermi liquid. Because of interactions and the presence of sharp Fermi surfaces, the quasiparticle energy contains, as a function of the momentum $$\varvec{p}$$ p , a term of the form $$( p - p_0)^3 \ln {( |p-p_0|/p_0)} $$ ( p - p 0 ) 3 ln ( | p - p 0 | / p 0 ) , where $$p = | \varvec{p} |$$ p = | p | and $$p_0$$ p 0 is the Fermi momentum. The electronic specific heat coefficient, magnetic susceptibility (Knight shift), electrical resistivity, Hall coefficient and thermoelectric power divided by temperature follow, as functions of temperature T, the logarithmic formula $$a-b T^2 \ln {(T/T^*)}$$ a - b T 2 ln ( T / T ∗ ) , $$a, \, b$$ a , b and $$T^*$$ T ∗ being constant; these formulae have been shown to explain the observed data for all iron-based superconductors. It is shown that the concept of non-Fermi liquids or anomalous metals which appears in the literature is not needed for descriptions of the present systems. When the superconducting transition temperature $$T_{\mathrm {C}}$$ T C and the b / a value for the resistivity are plotted as functions of the doping content x, there appear various characteristic diagrams in which regions of positive correlation and those of negative correlation between $$T_{\mathrm {C}}$$ T C and b / a are interconnected; from these diagrams, we may make speculations about the types of superconductivity and the crossover between them.

Effect of Various Processing Route on Microstructure and Mechanical Properties of Spray-Deposited Al-8.6Zn-2.6Mg-2.2Cu Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 1424-1427
Author(s):  
Feng Wang ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Bao Hong Zhu ◽  
Hong Wei Liu ◽  
...  
Keyword(s):  
Spray Deposition ◽  
Hot Extrusion ◽  
Processing Route ◽  
Microstructural Development ◽  
X Ray Diffraction ◽  
Cu Alloy ◽  
Uniform Microstructure ◽  
Near Net Shape ◽  
Hot Rolled ◽  
Rapidly Solidified

Spray deposition is a novel process which is used to manufacture rapidly solidified bulk and near-net-shape preforms. In this paper, Al-8.6Zn-2.6Mg-2.2Cu alloy was synthesized by the spray atomization and deposition technique. The microstructural development during subsequent hot extrusion, hot rolling and canned forging was investigated by means of scanning electron microscope and X-ray diffraction. The results indicate that the spray-deposited alloy exhibits a uniform microstructure composed of the Al matrix and Mg(ZnCu)2 compounds with various shape. The fragmentation of the Mg(ZnCu)2 phases in the alloy has been regarded as one of the main phenomena during extrusion, rolling and forging. Under T6 temper condition, the hot-extruded Al-Zn-Mg-Cu alloy displays superior strength, and higher than hot-rolled and canned-forged ones.

scholarly journals Effects of Solidification Cooling Rate on the Microstructure of Nickel Based Superalloy GTD222

2019 ◽  
Author(s):  
Bo Gao ◽  
Yanfei Sui ◽  
Hongwei Wang ◽  
Chunming Zou ◽  
Zunjie Wei ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Alloying Elements ◽  
Solidification Behavior ◽  
Cooling Rates ◽  
Dendrite Arm Spacing ◽  
Nickel Based Superalloy

The microstructure and solidification behavior of nickel based GTD222 superalloy at different cooling rates are studied. The solidification of the GTD222 superalloy proceeds as follows: L→L+γ, L→L+γ+MC, L→L+(γ/γ ′)-Eutectic and L→η phase. The temperature of liquidus of GTD222 superalloy is 1360 °C while the solidus is slightly lower at 1310 °C, which due to the alloying elements redistribution. It was found that the dendrite arm spacing of the alloy decreased with the increase of cooling rate (From 200 μm at 2.5 K/min to 100 μm at 20 K/min).

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