The quality of powder used in powder bed-based additive manufacturing plays a key role concerning process performance and end part properties. Even though this is a generally accepted fact, there is still a lack of a comprehensive understanding of the powder property-part property relationship. However, numerous investigations focusing on selected powder properties and their corresponding influence on process aspects or final part properties have been published in recent years. Still, generalized statements on powder requirements for a defined process performance are not available. This can be attributed to the fact that the community has not yet come to an agreement which characterization techniques are most suitable for powder characterization in the additive manufacturing context and in most cases only selected aspects have been investigated for special powder materials. The aim of this review is to assess these building blocks of knowledge and to provide an overview on the current state of the art.

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Lately high-entropy alloys (HEAs) have been the topic of extensive research, as these materials are promising candidates for many challenging applications, as for example tools, moulds and functional coatings. In contrast to conventional alloys, HEAs consist of five or more principal elements, each having a concentration between 5 and 35 at.-%. Against expectations, HEAs show a rather simple microstructure consisting preferentially of cubic phases. Due to this microstructure, HEAs show promising properties, e.g. in terms of high-temperature stability, high strength and ductility. Within this research, a single-phase CoCrFeMnNi HEA was produced by powder metallurgy (PM). In contrast to conventional metallurgy, PM offers a lot of advantages, e.g. good material efficiency and high shape complexity. Gas atomised powder was used and selected PM methods are presented (e.g. pressureless sintering, spark plasma sintering, additive manufacturing (EBM)). The process methods were evaluated by characterising the material properties (density, microstructure, mechanical properties) of the compacted and sintered samples

A number of nickel‐based and iron‐based alloys have been successfully developed for applications at high service temperatures and in corrosive environments. Applications such as diesel particulate filters, heat exchangers, and catalyst supports require open‐cell porous structures with tailored and uniform material and structural properties, a requirement which can be met by high temperature and corrosion resistant metallic alloy foams prepared with compositions similar to those mentioned above. A new technology that transforms pure nickel foam into an alloy foam, and which has now reached the pilot plant production stage, will be introduced. This technique starts from commercially‐available nickel foam, which is uniformly coated with a pre‐alloyed powder using standard powder metallurgical methods, and subsequently transformed into the desired alloy throughout the strut cross‐section in a relatively short time with a carefully controlled heat treatment that utilizes transient liquid‐phase sintering. This process allows for the preparation of a wide variety of foam compositions and structural features, which is important for tailoring material properties to a specific application.

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