Selective laser melting of metal structures onto graphite substrates via a low melting point interlayer alloy

Azizi, Arad; Chen, Xiaobo; Gou, Feilin; Hejripour, Fatemeh; Goodman, Jacob A.; Bae, In Tae; Rangarajan, Srikanth; Arvin, Charles; Sammakia, Bahgat; Ke, Changhong; Zhou, Guangwen; Schiffres, Scott N.

doi:10.1016/j.apmt.2021.101334

Cited by 3 publications

(2 citation statements)

References 36 publications

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“…This information has important implications for thermal-based nondestructive testing that can use local thermal conductivity information to infer local microstructure and defects (Schiffres et al , 2020), modeling the print process and residual stresses, and understanding properties of printed parts with thermal applications, especially those that cannot be heat treated (e.g. embedded sensors or print onto electronic chips (Azizi, 2019a, 2019b, 2022; Azizi and Schiffres, 2018; Schiffres and Azizi, 2021)).…”

Section: Introductionmentioning

confidence: 99%

Process-dependent anisotropic thermal conductivity of laser powder bed fusion AlSi10Mg: impact of microstructure and aluminum-silicon interfaces

Azizi

Hejripour

Goodman

et al. 2023

RPJ

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Purpose AlSi10Mg alloy is commonly used in laser powder bed fusion due to its printability, relatively high thermal conductivity, low density and good mechanical properties. However, the thermal conductivity of as-built materials as a function of processing (energy density, laser power, laser scanning speed, support structure) and build orientation, are not well explored in the literature. This study aims to elucidate the relationship between processing, microstructure, and thermal conductivity. Design/methodology/approach The thermal conductivity of laser powder bed fusion (L-PBF) AlSi10Mg samples are investigated by the flash diffusivity and frequency domain thermoreflectance (FDTR) techniques. Thermal conductivities are linked to the microstructure of L-PBF AlSi10Mg, which changes with processing conditions. The through-plane exceeded the in-plane thermal conductivity for all energy densities. A co-located thermal conductivity map by frequency domain thermoreflectance (FDTR) and crystallographic grain orientation map by electron backscattered diffraction (EBSD) was used to investigate the effect of microstructure on thermal conductivity. Findings The highest through-plane thermal conductivity (136 ± 2 W/m-K) was achieved at 59 J/mm3 and exceeded the values reported previously. The in-plane thermal conductivity peaked at 117 ± 2 W/m-K at 50 J/mm3. The trend of thermal conductivity reducing with energy density at similar porosity was primarily due to the reduced grain size producing more Al-Si interfaces that pose thermal resistance. At these interfaces, thermal energy must convert from electrons in the aluminum to phonons in the silicon. The co-located thermal conductivity and crystallographic grain orientation maps confirmed that larger colonies of columnar grains have higher thermal conductivity compared to smaller columnar grains. Practical implications The thermal properties of AlSi10Mg are crucial to heat transfer applications including additively manufactured heatsinks, cold plates, vapor chambers, heat pipes, enclosures and heat exchangers. Additionally, thermal-based nondestructive testing methods require these properties for applications such as defect detection and simulation of L-PBF processes. Industrial standards for L-PBF processes and components can use the data for thermal applications. Originality/value To the best of the authors’ knowledge, this paper is the first to make coupled thermal conductivity maps that were matched to microstructure for L-PBF AlSi10Mg aluminum alloy. This was achieved by a unique in-house thermal conductivity mapping setup and relating the data to local SEM EBSD maps. This provides the first conclusive proof that larger grain sizes can achieve higher thermal conductivity for this processing method and material system. This study also shows that control of the solidification can result in higher thermal conductivity. It was also the first to find that the build substrate (with or without support) has a large effect on thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Process-dependent anisotropic thermal conductivity of laser powder bed fusion AlSi10Mg: impact of microstructure and aluminum-silicon interfaces

Azizi

Hejripour

Goodman

et al. 2023

RPJ

Self Cite

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“…In addition, there was a resultant discontinuously formed along the interface, which was identified as Ga 4 Ti 5 . Azizi et al [ 14 ] found that the Ti in the Sn3Ag4Ti alloy formed a 10 nm TiC layer at the graphite interface after the laser melting of metal structures onto a graphite substrate. The Sn-Ag-Ti-based solder can be applied without the flux or preliminary coating of substrates and is free from lead or cadmium, corresponding to the requirements of all the environmental initiatives for lead-free soldering (RoHS etc.)…”

Section: Introductionmentioning

confidence: 99%

Study of Wettability and Solderability of SiC Ceramics with Ni by Use of Sn-Sb-Ti Solder by Heating with Electron Beam in Vacuum

et al. 2022

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The aim of this research was to study the wettability and solderability of SiC ceramics by the use of an active solder of the type Sn5Sb3Ti in a vacuum by electron beam heating. This solder exerts a narrow melting interval, and only one thermal effect, a peritectic reaction, was observed. The liquidus temperature of the solder is approximately 243 °C. The solder consists of a tin matrix where the Ti6(Sb,Sn)5 and TiSbSn phases are precipitated. The solder wettability on a SiC substrate decreases with decreasing soldering temperature. The best wetting angle of 33° was obtained in a vacuum at the temperature of 950 °C. The bond between the SiC ceramics and the solder was formed due to the interaction of Ti and Ni with silicon contained in the SiC ceramics. The formation of new TiSi2 and Ti3Ni5Si6 phases, which form the reaction layer and thus ensure the bond formation, was observed. The bond with Ni is formed due to the solubility of Ni in the tin solder. Two phases, namely the Ni3Sn2 and Ni3Sn phases, were identified in the transition zone of the Ni/Sn5Sb3Ti joint. The highest shear strength, around 40 MPa, was attained at the soldering temperature of 850 °C.

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Joining of Aluminum and CFRP via Laser Powder Bed Fusion: Influence of Experimental Set-Up and Laser Processing on Microstructure and Mechanical Properties

Nester,

Meinhard,

Schanz

et al. 2023

Polymers

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Additive-manufacturing-based joining methods enable tailored or even functionalized joints and allow for hybridization at small scales. The current study explored an innovative joining method for aluminum cast alloys (AlSi12) with thermoset carbon-fiber-reinforced polymers (CFRPs) via laser powder bed fusion (LPBF). The direct build-up of AlSi12 on a CFRP substrate proved to be challenging due to the dissimilar thermal properties of the considered materials, which led to substrate damage and low joint adhesion. These effects could be overcome by introducing an AlSi12 foil as an interlayer between the two joining partners, acting as a thermal barrier and further improving the AlSi12 melt wettability of the substrate. Within LPBF, the energy input in the form of volumetric laser energy density influenced both the porosity of the fused layers and the formation of thermally induced stresses due to the high cooling rates and different thermal expansion properties of the materials. While the AlSi12 volume density increased with a higher laser energy input, simultaneously increasing thermal stresses caused the debonding and deformation of the AlSi12 foil. However, within a narrow processing window of laser parameters, the samples achieved remarkably high shear strengths of τ > 20 MPa, comparable to those of conventional joining methods.

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Selective laser melting of metal structures onto graphite substrates via a low melting point interlayer alloy

Cited by 3 publications

References 36 publications

Process-dependent anisotropic thermal conductivity of laser powder bed fusion AlSi10Mg: impact of microstructure and aluminum-silicon interfaces

Process-dependent anisotropic thermal conductivity of laser powder bed fusion AlSi10Mg: impact of microstructure and aluminum-silicon interfaces

Study of Wettability and Solderability of SiC Ceramics with Ni by Use of Sn-Sb-Ti Solder by Heating with Electron Beam in Vacuum

Joining of Aluminum and CFRP via Laser Powder Bed Fusion: Influence of Experimental Set-Up and Laser Processing on Microstructure and Mechanical Properties

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