Page - 109 - in 3D Printing of Metals
Image of the Page - 109 -
Text of the Page - 109 -
Metals 2016,6, 286
toprepare ceramicparticle reinforcedaluminummatrix composites, coatings, or both to improve
the corresponding properties of aluminum [2]. Normally, in order to enhance the performance
of aluminum, the ceramic particles are employed as reinforcements to be directly added to the
molten aluminum. For instance, the additive of Al2O3 and B4C ceramic particles were added
to the aluminumcomposites to strengthen themechanical properties [3].However, owing to the
considerablypoorwettabilitybetweenceramicsparticleandaluminum,apoor interfacialbonding
betweenthereinforcementsandthematrix isgenerated,whichconsiderably influences themechanical
performances of the AMCs. In the literature, the in situ synthesis of the reinforcements of the
particle-reinforcedmetalmatrixcomposites isanewtechnique,which isachievedbyaddingelement
and compoundpowder or performs into themolten aluminum. In the case of in situ synthesis,
thedesiredreinforcedparticlescanbesynthesizeddirectlyusingthechemical reactionbetweenthe
reactants in themelt [4]. Insitureactionprocesses involvingparticle-reinforcedcomposite systems
eliminate interfacial compounds infavorofnucleationandgrowthfromtheparentmatrixphase to
formmore thermodynamically stable reinforced compounds. Meanwhile, the compositespossess
contaminant-free reinforcement/matrix interfaces, and the in situAl2O3 particles arefineandcan
enhance the strength and ductility of the composite. Compared with the previous techniques,
advantagesareas follows: (i) thedistributionof the insitureinforcementsaremorehomogeneous in
thewholemicrostructuresandmore thermodynamicallystable; (ii) the insitureinforcementshave
ametallurgicalbondingwith thematrix,whichresults inastrong interfacialbondingbetween the
reinforcementsandthematrix. Recently, somemetaloxides (e.g.,Fe2O3,MnO2,andCuO)wereadded
tomolten aluminum toproduceAl2O3 particle reinforcementwith ahighperformance, lowcost,
andgoodwettability,which can take the external loadand thegood interfacial cohesionbetween
Al2O3 and thematrix [4]. Inan insituAl/CuOcomposite system,oxygenatomsdiffusealong the
powder surfaces and the lattice andgrain boundaries during synthesis, and anoxidefilmon the
surfaceof ametalpowderhasa significant effecton thebondingpropertiesof thepowder. In this
case, theoxidefilmcanaccelerate thebondingbetweenparticleswhenthefilmthickness is less than
critical. The insituSLMreactionofAl/Fe2O3powdermixturesreleasedextraheatandcollaborated
with laser energy, which can modify the visual surface and microstructural appearance or alter
material characteristics,andthehardnessofcompositewas increased[5]. Further takingtheAl2O3
as the rawmaterial, thehigh-performanceAl2Si4O10 reinforcedaluminumwas insitusynthesized
bypowdermetallurgytechniqueandtheresultantmechanicalpropertiesofAMCswasconsiderably
enhanced[6].Althoughthepresenceofreinforcements insitusynthesizedinthealuminumcomposites
canstrengthentheperformanceof thecorrespondingaluminummatrixefficiently, theconventional
AMCsreinforcedbyinsitusynthesizedreinforcementsusingmicro-scaleparticlescommonlyhavea
remarkablycoarsemicrostructurewithattendantpoormechanicalperformanceresulting fromaslow
coolingrate in traditionalmanufacturingprocesses [7].
Additivemanufacturing(AM)/3Dprinting(3DP)refers to theprocessof fabricatingthree-dimensional
near-net-shapedcomponentsdirectly frompowderparticles ina layer-by-layermanner. It enables
anumberof technical andeconomicadvantages, e.g., improving the cost-competitiveness for low
volume production, reducing the environmental impact of manufacture, and increasing design
complexity [8]. Selective lasermelting(SLM),anewlydevelopedAM/3DPprocess, isbasedonthe
principle ofmaterial incrementalmanufacturing and considered a promisingAM technology for
metallicparts,due to itsflexibility in feedstockandshapes.SLMprovidespossibilities to fabricate the
geometricallycomplexcomponentsbyuser-definedcomputer-aideddesign(CAD)fileswithout tools
ormolds thatwouldbedifficult todevelopbyconventionalmanufacturingmethods. It enables the
quick fabricationof thegeometry-complexcomponentsdirectly frompowders.Under the irradiation
of thehigh-energy laserbeam,SLMfabricatesparts ina layer-wise fashionbyselectively fusingand
consolidatingthethinlayersof theloosepowder[9].Generally, thegeometricallycomplexcomponents
are fabricatedbySLMwithahighdimensionalprecisionandgoodsurface integritywithoutother
subsequentprocess requirements,which theconventional techniques (e.g., castingandmachining)
109
back to the
book 3D Printing of Metals"
3D Printing of Metals
- Title
- 3D Printing of Metals
- Author
- Manoj Gupta
- Editor
- MDPI
- Location
- Basel
- Date
- 2017
- Language
- English
- License
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03842-592-2
- Size
- 17.0 x 24.4 cm
- Pages
- 170
- Keywords
- 3D printing, additive manufacturing, electron beam melting, selective laser melting, laser metal deposition, aluminum, titanium, magnesium, composites
- Categories
- Naturwissenschaften Chemie