Multi-scale defects in powder-based additively manufactured metals and alloys

Fu, Jin; Li, H.; Song, Xu; Fu, Ming

doi:10.1016/j.jmst.2022.02.015

Cited by 171 publications

(37 citation statements)

References 254 publications

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“…Figure c shows the compressive strengths of SPS and SLM samples, and they are 52 and 113 MPa, respectively. Compared with the SPS sample, the compression strength in the SLM sample was enhanced, which was mainly attributed to the high density of dislocations and nanotwins introduced through the nonequilibrium solidification of SLM . A high mechanical strength is essential to ensure the stability of TEGs for long-term service.…”

Section: Resultsmentioning

confidence: 99%

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Luo

Guo

et al. 2022

ACS Appl. Mater. Interfaces

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High-energy-conversion Bi 2 Te 3 -based thermoelectric generators (TEGs) are needed to ensure that the assembled material has a high value of average figure of merit (ZT ave ). However, the inferior ZT ave of the n-type leg severely restricts the large-scale applications of Bi 2 Te 3 -based TEGs. In this study, we achieved and reported a high peak ZT (1.33) of three-dimensional (3D)printing n-type Bi 2 Te 2.7 Se 0.3 . In addition, a superior ZT ave of 1.23 at a temperature ranging from 300 to 500 K was achieved. The high value of ZT ave was obtained by synergistically optimizing the electronic-and phonon-transport properties using the 3D-printing-driven defect engineering. The nonequilibrium solidification mechanism facilitated the multiscale defects formed during the 3D-printed process. Among the defects formed, the nanotwins triggered the energy-filtering effect, thus enhancing the Seebeck coefficient at a temperature range of 300−500 K. The effective scattering of wide-frequency phonons by multiscale defects reduced the lattice thermal conductivity close to the theoretical minimum of ∼0.35 W m −1 k −1 . Given the advantages of 3D printing in freeform device shapes, we assembled and measured bionic honeycombshaped single-leg TEGs, exhibiting a record-high energy conversion efficiency (10.2%). This work demonstrates the great potential of defect engineering driven by selective laser melting 3D-printing technology for the rational design of advanced n-type Bi 2 Te 2.7 Se 0.3 thermoelectric material.

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Section: Resultsmentioning

confidence: 99%

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Luo

Guo

et al. 2022

ACS Appl. Mater. Interfaces

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“…In contrast, KHs observed in L-PBF parts are typically smaller than 100 µm (i.e., dependent on the laser spot diameter) and GEPs are even smaller. Even though the formation mechanisms of various types of defects are well known 9,[27][28][29] , classifying them according to one or two simple measures of size, sphericity, and aspect ratio has been challenging. This could be explained by different defect types sharing overlaps in their value ranges of these parameters; therefore, they cannot be distinguished by a clear threshold.…”

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confidence: 99%

Feature-based volumetric defect classification in metal additive manufacturing

Poudel

Yasin

et al. 2022

Nat Commun

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Volumetric defect types commonly observed in the additively manufactured parts differ in their morphologies ascribed to their formation mechanisms. Using high-resolution X-ray computed tomography, this study analyzes the morphological features of volumetric defects, and their statistical distribution, in laser powder bed fused Ti-6Al-4V. The geometries of three common types of volumetric defects; i.e., lack of fusions, gas-entrapped pores, and keyholes, are quantified by nine parameters including maximum dimension, roundness, sparseness, aspect ratio, and more. It is shown that the three defect types share overlaps of different degrees in the ranges of their morphological parameters; thus, employing only one or two parameters cannot uniquely determine a defect’s type. To overcome this challenge, a defect classification methodology incorporating multiple morphological parameters has been proposed. In this work, by employing the most discriminating parameters, this methodology has been shown effective when implemented into decision tree (>98% accuracy) and artificial neural network (>99% accuracy).

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“…f and g express the mass fraction and volume fraction, and the thermophysical properties in the calculate domain are defined as Eqs. ( 7)- (9).…”

Section: ( ) ( ) ( )mentioning

confidence: 99%

“…Available aerospace equipment requires products with satisfactory precision, acceptable quality, and minus defects [3,7,8] . Currently, the main drawbacks in parts fabricated by the DED technology include dishing, humping, and balling of the solidified area [9] . To obtain higher quality parts, conditions control, and melt pool monitoring has been crucial strategy in DED [10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation on melt pool and solidification in the direct energy deposition process of GH3536 powder superalloy

Liu

Liu²,

Li³

et al. 2023

Preprint

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In the direct energy deposition (DED) process, the highly energetic laser, rapid melting, and solidification processes lead to complex heat transfer and flow phenomena. A three-dimensional finite element model (FEM) is established to study the effect of process parameters on the melt pool and solidification quality during the DED process. The heat transfer, fluid flow, and solidification in the DED process of the GH3536 superalloy are studied. By investigating the effects of laser power, scanning speed, and feed rate on the morphology of melt pool and interlayer fusion, the appropriate input parameters for GH3536 are obtained. Temperature gradient and solidification rate obtained in transient thermal distribution are applied to predict the quality and morphology of the solidified structure at the cut-off point. Results show that high laser power and low scanning speed or feed rate will enlarge the melt pool. Well-solidified microstructure frequently appears in the middle of the parameter set; focusing on the enlargement of the melt pool is not the best strategy. The correlation between feed rate and laser power is not obvious. The minimum threshold for scanning speed is found at a given feed rate. When the scanning rate is below the threshold, abnormal morphology of the melt pool and irregular solidification structures will occur. The laser power and scanning speed range suitable for the GH3536 superalloy are summarized, and the undesirable and possibly fluctuating parameters are marked. The middle part of the parameter set is recommended for the feed rate.

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Multi-scale defects in powder-based additively manufactured metals and alloys

Cited by 171 publications

References 254 publications

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Feature-based volumetric defect classification in metal additive manufacturing

Numerical simulation on melt pool and solidification in the direct energy deposition process of GH3536 powder superalloy

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Multi-scale defects in powder-based additively manufactured metals and alloys

Cited by 171 publications

References 254 publications

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi2Te2.7Se0.3 by 3D Printing-Driven Defect Engineering

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi2Te2.7Se0.3 by 3D Printing-Driven Defect Engineering

Feature-based volumetric defect classification in metal additive manufacturing

Numerical simulation on melt pool and solidification in the direct energy deposition process of GH3536 powder superalloy

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Product

Resources

About

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering