Introduction . Directed energy deposition (DED)1is a promising layer-by-layer additive manufacturing (AM) technology that fabricates complex geometries for high-value-added products2. DED is also applied to repair applications, such as the repair of damaged turbine blades3. However, the industrialisation of the DED process for applications in automotive, marine, aerospace and biomedical fields has been limited by porosity introduced during the process, as porosity can b...