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.

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.

국내 육성된 양송이 ‘새도’ 등 5개 품종으로 수확주기별 버섯의 형태적 변화를 확인하기 위하여 농가현장 시험을 통하여 생산성 및 품질을 평가하였다. 공시품종의 재배적 특성을 종합해보면 버섯발생 및 생육에 관련한 부분은 거의 비슷한 특성을 보였다. 전반적으로 균사 활력은 비슷하였으나 재배농가의 평가에서는 ‘새 도’ 품종이 강한 편이며, ‘새한’ 품종이 약한 것으로 평가하였다. 자실체의 개체중은 품종특성 보다는 농가별 퇴비의 상태 및 발생량이 관여하는 것으로 추정되며, 품종간의 차이를 구별할 수 없었다. 자실체의 갓 직경, 갓 두께, 대 길이 등의 특성에서 달성군, 용인시, 보령시 지역농가의 경우는 품종에 관계없이 첫주기에 대비하여 주기가 진행되면서 감소하였다. 하지만 대 굵기는 품종에 관계없이 첫 주기에 대비하여 2, 3주기에는 증가하는 경향이었다. 하지만 경주는 품종과 주기에 따른 어떤 경향을 확인할 수 없었으며, 부여에서는 갓 직경과 대 길이는 ‘새정’을 제외 한 품종들은 주기가 진전함에 따라 감소하였고, 갓 두께와 대 굵기는 품종간 일정하지 않았다. 이러한 수확주기 별 형태적 특성의 차이는 품종보다는 수확주기별로 배지에서의 양분의 공급량과 사용한 퇴비의 품질과 재배환경의 변화에 따른 차이에 의해 발생하는 것으로 예상된다.

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.