Liquid metal extraction (LME), a pyrometallurgical recycling method, is popular owing to its negligible environmental impact. LME mainly targets rare-earth permanent magnets having several rare-earth elements. Mg is used as a solvent metal for LME because of its selective and eminent reactivity with rare-earth elements in magnets. Several studies concerning the formation of Dy-Fe intermetallic compounds and their effects on LME using Mg exist. However, methods for reducing these compounds are unavailable. Fe reacts more strongly with B than with Dy; B addition can be a reducing method for Dy-Fe intermetallic compounds owing to the formation of Fe₂B, which takes Fe from Dy-Fe intermetallic compounds. The FeB alloy is an adequate additive for the decomposition of Fe₂B. To accomplish the former process, Mg must convey B to a permanent magnet during the decomposition of the FeB alloy. Here, the effect of Mg on the transfer of B from FeB to permanent magnet is observed through microstructural and phase analyses. Through microstructural and phase analysis, it is confirmed that FeB is converted to Fe₂B upon B transfer, owing to Mg. Finally, the transfer effect of Mg is confirmed, and the possibility of reducing Dy-Fe intermetallic compounds during LME is suggested.

AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a highquality additive manufacturing product.

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• Residual Stress Analysis of Additive Manufactured A356.2 Aluminum Alloys using X-Ray Diffraction Methods
  SangCheol Park, InYeong Kim, Young Il Kim, Dae-Kyeom Kim, Soong Ju Oh, Kee-Ahn Lee, Bin Lee
  Korean Journal of Metals and Materials.2023; 61(7): 534.     CrossRef

A well-established characterization method is required in powder bed fusion (PBF) metal additive manufacturing, where metal powder is used. The characterization methods from the traditional powder metallurgy process are still being used. However, it is necessary to develop advanced methods of property evaluation with the advances in additive manufacturing technology. In this article, the characterization methods of powders for metal PBF are reviewed, and the recent research trends are introduced. Standardization status and specifications for metal powder for the PBF process which published by the ISO, ASTM, and MPIF are also covered. The establishment of powder characterization methods are expected to contribute to the metal powder industry and the advancement of additive manufacturing technology through the creation of related databases.

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• Rheological Characteristic Analysis Methods and Tests of Metal Powders for PBF Additive Manufacturing
  Wan-Sik Woo, Ho-Jin Lee
  Journal of the Korean Society of Manufacturing Process Engineers.2023; 22(10): 1.     CrossRef
• Residual Stress Analysis of Additive Manufactured A356.2 Aluminum Alloys using X-Ray Diffraction Methods
  SangCheol Park, InYeong Kim, Young Il Kim, Dae-Kyeom Kim, Soong Ju Oh, Kee-Ahn Lee, Bin Lee
  Korean Journal of Metals and Materials.2023; 61(7): 534.     CrossRef
• Enhancing spreadability of hydrogenation-dehydrogenation titanium powder and novel method to characterize powder spreadability for powder bed fusion additive manufacturing
  Young Il Kim, Dae-Kyeom Kim, InYeong Kim, Sang Cheol Park, Dongju Lee, Bin Lee
  Materials & Design.2022; 223: 111247.     CrossRef

Powder characteristics, such as density, size, shape, thermal properties, and surface area, are of significant importance in the powder bed fusion (PBF) process. The powder required is exclusive for an efficient PBF process. In this study, the particle size distribution suitable for the powder bed fusion process was derived by modeling the PBF product using simulation software (GeoDict). The modeling was carried out by layering sintered powder with a large particle size distribution, with 50 μm being the largest particle size. The results of the simulation showed that the porosity decreased when the mean particle size of the powder was reduced or the standard deviation increased. The particle size distribution of prepared titanium powder by the atomization process was also studied. This study is expected to offer direction for studies related to powder production for additive manufacturing.

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• Review of “Integrated Computer-Aided Process Engineering Session in the International Symposium on Innovation in Materials Processing (ISIMP, 26–29 October 2021)”
  Hyunjoo Choi, Jungjoon Kim, Pil-Ryung Cha, Hyoung Seop Kim
  MATERIALS TRANSACTIONS.2023; 64(10): 2542.     CrossRef