Copper powder densification by means of DMLF process: the effect of energy density input and oxidation

Abstract

Densification of pure copper powder beds was obtained during a Direct Metal Laser Fabrication (DMLF) process using a system developed by the authors. The resulting powder densification was measured by means of gas pycnometry. The effect on densification from three process parameters, namely: scan step, scan speed and initial environment temperature was studied. As expected, it was found that the powder densification observed increases with decreasing scan step and scan speed. Concerning increasing initial temperature, densification showed a slight increasing trend. Total energy density input was considered in order to relate these three parameters with the measured percentage densification of the powder. An exponential model was fitted to these magnitudes. Densification value approached an asymptotic level near 91.6 %. Lack of high vacuum environment, as well as oxygen contamination of the powder, are believed to be the main reasons for the presence of oxidation and a low degree of mass densification observed in some specimens.