In a selective laser melting process, it is common to reuse the powder in consecutive cycles of the route because it is more sustainable and cost effective. However, it is unknown whether reusing the material has an influence on the process. In this paper, Inconel 718, Ti6Al4V, AlSi10Mg and Scalmalloy are characterized to determine the impact of reusing powders on the additive manufacturing (AM) process under an argon high-purity atmosphere. Virgin powders were taken from the suppliers and compared to powders that had been used in the process for a long period of time with periodic ‘rejuvenation’. A well-structured characterization procedure, combining many existing techniques, is proposed, determining changes in the morphology, composition (chemical and microstructure) and flowability. Clear differences between the virgin and used state are revealed by the characterizations; AlSi10Mg, appears to be the most sensitive to reuse with changes in particle size distribution and morphology, and with an increase in the oxygen content. The main contribution of this paper is providing insight into the effects of reuse for four commonly used AM powders, by means of a simple but well-structured method that links the particle feature characterization process to the flowability of metal AM powders. The provided insights enable enhanced decision-making on recycling and reuse of powder for specific AM processes.

High entropy alloys have attracted much interest over the last 16 years due to their promising an unusual properties in different fields that offer many new possible application. Additionally, additive manufacturing has drawn attention due to its versatility and flexibility ahead of a new material challenge, being a suitable technology for the development of metallic materials. Moreover, high entropy alloys have demonstrated that many gaps exist in the literature on its physical metallurgy, and in this sense, additive manufacturing could be a feasible technology for solving many of these challenges. In this review paper the newest literature on this topic is condensed into three different aspects: the different additive manufacturing technologies employed to process high entropy alloys, the influence of the processing conditions and composition on the expected structure and microstructure and information about the mechanical and corrosion behavior of these alloys.