Direct laser sintering of metal powders: Mechanism, kinetics and microstructural features

Simchi, A.

doi:10.1016/j.msea.2006.04.117

Cited by 496 publications

(238 citation statements)

References 18 publications

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“…The temperature gradients in the pool give rise to surface tension gradients and resultant Marangoni convention. 29 Because of the combined effect of Marangoni flow and the poor flowability of the melt caused by the high viscosity, the melt tends to flow radially inward toward the melt pool center, instead of spreading outward on the underlying surface. 30 Consequently, the instable melt track breaks up into several spherical agglomerates to achieve the equilibrium state, which is termed as "balling" effect.…”

Section: B Densification Behaviormentioning

confidence: 99%

Densification behavior, microstructure evolution, and wear property of TiC nanoparticle reinforced AlSi10Mg bulk-form nanocomposites prepared by selective laser melting

Wang

Dai

et al. 2014

Journal of Laser Applications

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Selective laser melting (SLM), due to its unique additive manufacturing processing philosophy, demonstrates a high potential in producing bulk-form nanocomposites with novel nanostructures and enhanced properties. In this study, the nanoscale TiC particle reinforced AlSi10Mg nanocomposite parts were produced by SLM process. The influence of “laser energy per unit length” (LEPUL) on densification behavior, microstructural evolution, and wear property of SLM-processed nanocomposites was studied. It showed that using an insufficient LEPUL of 250 J/m lowered the SLM densification due to the balling effect and the formation of residual pores. The highest densification level (>98% theoretical density) was achieved for SLM-processed parts processed at the LEPUL of 700 J/m. The TiC reinforcement in SLM-processed parts experienced a structural change from the standard nanoscale particle morphology (the average size 75–92 nm) to the relatively coarsened submicron structure (the mean particle size 161 nm) as the applied LEPUL increased. The nanostructured TiC reinforcement was generally maintained within a wide range of LEPUL from 250 to 700 J/m and the dispersion state of nanoscale TiC reinforcement was homogenized with increasing LEPUL. The sufficiently high densification rate combined with the uniform distribution of nanoscale TiC reinforcement throughout the matrix led to the considerably low coefficient of friction of 0.38 and wear rate of 2.76 × 10−5 mm3 N−1 m−1 for SLM-processed nanocomposites at 700 J/m. Both the insufficient SLM densification response at a relatively low LEPUL of 250 J/m and the disappearance of nanoscale reinforcement at a high LEPUL of 1000 J/m lowered the wear performance of SLM-processed nanocomposite parts.

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Section: B Densification Behaviormentioning

confidence: 99%

Densification behavior, microstructure evolution, and wear property of TiC nanoparticle reinforced AlSi10Mg bulk-form nanocomposites prepared by selective laser melting

Wang

Dai

et al. 2014

Journal of Laser Applications

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“…Some of tested materials are (Alemohammad et al, 2007;Simchi, 2006;Wu et al, 2002;Yellup, 1995 Although the material can be supplied b oth in powder and in wire form, powder is generally used for several reasons: the process is more flexible because, at any time, the changes in the layer thickness and in the composition of material are possible; many more elements and alloys are available in powder; there is no direct contact with the molten pool; the laser beam can pass through the powder flow, instead of being intercepted by the wire. The flexibility that acquires the process through the use of powders of different metals is extraordinary (Liu & DuPont, 2003).…”

Section: Process Materialsmentioning

confidence: 99%

Experimental Analysis of the Direct Laser Metal Deposition Process

Ludovico¹,

Angelastro²,

Campanelli³

2010

New Trends in Technologies: Devices, Computer, Communication and Industrial Systems

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“…Research in the field of Selective Laser Melting (SLM) is broad, with many focused on parameter optimisation for achieving consistent high density parts and establishing a relationship between parameters and final part mechanical properties for specific materials [1][2][3][4][5][6][7][8][9][10][11][12][13]. Understanding the phenomenon of residual stresses building up in SLM parts due to high thermal gradients and strategies for minimising the residual stresses and their detrimental effects such as cracking and warping of parts are other areas of interest for researchers [14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

In-Built Customised Mechanical Failure of 316L Components Fabricated Using Selective Laser Melting

2017

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Abstract:The layer-by-layer building methodology used within the powder bed process of Selective Laser Melting facilitates control over the degree of melting achieved at every layer. This control can be used to manipulate levels of porosity within each layer, effecting resultant mechanical properties. If specifically controlled, it has the potential to enable customisation of mechanical properties or design of in-built locations of mechanical fracture through strategic void placement across a component, enabling accurate location specific predictions of mechanical failure for fail-safe applications. This investigation examined the process parameter effects on porosity formation and mechanical properties of 316L samples whilst maintaining a constant laser energy density without manipulation of sample geometry. In order to understand the effects of customisation on mechanical properties, samples were manufactured with in-built porosity of up to 3% spanning across~1.7% of a samples' cross-section using a specially developed set of "hybrid" processing parameters. Through strategic placement of porous sections within samples, exact fracture location could be predicted. When mechanically loaded, these customised samples exhibited only~2% reduction in yield strength compared to samples processed using single set parameters. As expected, microscopic analysis revealed that mechanical performance was closely tied to porosity variations in samples, with little or no variation in microstructure observed through parameter variation. The results indicate that there is potential to use SLM for customising mechanical performance over the cross-section of a component.

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Direct laser sintering of metal powders: Mechanism, kinetics and microstructural features

Cited by 496 publications

References 18 publications

Densification behavior, microstructure evolution, and wear property of TiC nanoparticle reinforced AlSi10Mg bulk-form nanocomposites prepared by selective laser melting

Densification behavior, microstructure evolution, and wear property of TiC nanoparticle reinforced AlSi10Mg bulk-form nanocomposites prepared by selective laser melting

Experimental Analysis of the Direct Laser Metal Deposition Process

In-Built Customised Mechanical Failure of 316L Components Fabricated Using Selective Laser Melting

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