Direct metal deposition (DMD) is a unique technique combining laser and powder processing, which enhances material utilisation by enabling manufacture of high precision near-net shape components from powders. Rapid prototyping, in-situ repair and surfacing are amongst the capabilities of DMD, and typical applications cover industry sectors which mainly include medical, defence and aerospace but with potential applications in other sectors, such as oil and gas. Despite the major advantages of rapid fabrication of parts with complex geometries and automated repair, there is, however, a need to develop a full understanding of the process-structure-property relationships, with a particular emphasis on the effect of powder characteristics, such as powder particle size, shape and distribution on process variables, and the metallurgy and resulting mechanical properties, which are crucial for many in service applications. This paper presents a brief overview of the DMD process from a powder metallurgy perspective and seeks to highlight the effect of process parameters and with powder characteristics, on the structure and properties that can be achieved, with an emphasis on underlying mechanisms and attendant metallurgical issues. Finally, recent developments in the current state-of-art are discussed, and potential applications combining powder metallurgy and DMD are identified.
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