Inductively Coupled Plasma Process for Reconditioning Ti and Ni Alloy Powders for Additive Manufacturing

In laser powder bed fusion additive manufacturing (AM), the number of build cycles required for a powder to go from its virgin state to a state that can alter final part mechanical properties is currently unknown. While ideal, the use of virgin powder for every AM build is not practical or economical. It is critical to investigate new methods that will help mitigate these cost drivers and enable the use of recycled powder in AM. Presented here is initial work on the use of an inductively coupled plasma (ICP) process to recondition AM powders used in laser and electron beam powder bed fusion, highlighting some challenges faced while developing optimum process parameters. The manuscript focuses on the three-dimensional characterization of used powder, before and after the plasma reconditioning process, in order to quantitatively understand the result of the ICP process on the shape and porosity of the particles. A distinct change in the morphology of the powder was observed before and after the ICP where most, but not all, irregular shaped powder particles and multi-particles were converted into more spherical particles. A detailed analysis of the percentage of spherical and non-spherical particles before and after the ICP process is also included, as well as the process' effect on particle porosity, which was different for the two powders used, Inconel 718 and Ti-6Al-4V. The results indicate the value of using the ICP process as a viable option for recycling of these two powders.