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.

The surface roughness of Al, Ag and Ni nano-powders which were prepared by pulsed wire evaporation method was quantified based upon the fractal theory. The surface fractal dimensions of metal nano-powders were determined from the linear relationship between In and Inln () using multi-layer gas adsorption theory. Moreover, the fractal surface image was realized by computer simulation. The relationship between preparation condition and surface characteristics of metal nano-powders was discussed in detail.

It was investigated whether mechanical alloying (MA) processing could be more effective to the formation of metallic composite powder in Cu-C system. Elemental powder mixtures of Cu-70vo1.%C were mechanically alloyed with an attritor in an argon atmosphere and microstructural evolution was examined by X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. It has been found that even with the high volume fraction of immiscible graphite in Cu-C system, the refinement with a few ten nanometer size as well as the highly uniform distribution of copper phases have been achieved by the MA processing.