ABSTRACT
Directed energy deposition (DED) processes are a group of techniques which develop parts by melting the material when it is being deposited. According to the International Organization for Standardization/American Society for Testing and Materials definition, DED is an additive manufacturing process in which focused thermal energy is used to fuse materials by melting as they are being deposited. “Focused thermal energy” means that an energy source is focused to melt the materials being deposited. Material as well as an energy source is simultaneously introduced in DED processes. Direct melting of the material in the form of powder or filament occurs by means of the energy source at the deposition location. Creation of a melt pool occurs as the energy source interacts with the material. This pool undergoes instantaneous solidification with the retraction of the energy source from the deposition location. DED techniques can be classified according to the source of energy.
