Impact of pre-treatments on the surface composition, the optical and flow properties of a CuCrZr powder dedicated to laser powder bed fusion use

Laser Powder Bed Fusion is not power efficient at processing copper‑chromium‑zirconium alloy due to the high reflectivity of the powder at the laser standard wavelength (1070 nm). A way to reduce the optical reflectivity is to modify the powder surface. This work aims to study the impact of reduction and oxidation pre-treatments on the surface chemistry of the particles, and to understand their consequences on the powder properties. X-ray photoelectron spectroscopy analyses show that, starting from a 2–3 nm thick native Cu 2 O layer, a wet atmosphere leads to the formation of a 54 nm thick Cu 2 O layer, whereas a reduction under hydrogen leads to pure copper. Under argon, the Cu 2 O thickness slightly increases up to 3–4 nm. The oxidation and the reduction treatments improve the flowability, respectively, by 46% and 26%. The reduction increases the reflectivity by 2%, whereas the oxidation reduces it by 26%.