Surface chemistry in Ti-6Al-4V feedstock as influenced by powder reuse in electron beam powder-bed fusion

Published

July 18, 2022

Author(s)

Nicholas Derimow, Justin Gorham, May Ling Martin, Jake Benzing, Ryan White, Nik Hrabe

Abstract

X-ray photoelectron spectroscopy (XPS) as well as scanning and transmission electron microscopy (SEM/TEM/STEM) analysis was carried out on four Ti-6Al-4V powders used in electron beam powder-bed fusion (PBF-EB) production environments: virgin low oxygen (0.080 wt% O), reused medium oxygen (0.140 wt% O), reused high oxygen (0.186 wt% O), and virgin high oxygen (0.180 wt% O). The two objectives of this comparative analyses were to (1) investigate high oxygen containing Grade 23 Ti-6Al-4V powders which were further oxidized as a function of reuse and (2) comparing the two virgin Grade 23 and Grade 5 powders of similar oxygen content. The microstructure of the low oxygen virgin Grade 23 powder was consistent with martensitic α' microstructure, whereas the reused powder displayed tempered α/β Widmänstatten microstructure. XPS revealed a decrease in TiO2 at the surface of the reused powders with an increase in Al2O3. This trend is energetically favorable at the temperatures and pressures in PBF-EB machines, and it is consistent with the thermodynamics of Al2O3 vs. TiO2 reactions. An unexpected amount of nitrogen was measured on the titanium powder, with a general increase in nitride on the surface of the particles as a function of reuse in the Grade 23 powder.

Citation

Applied Surface Science

Volume

602

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.apsusc.2022.154280

Local Download

Keywords

additive manufacturing, Ti-6Al-4V, Oxidation, Powder Recycling, Powder Reuse, XPS

Citation

Derimow, N. , Gorham, J. , Martin, M. , Benzing, J. , White, R. and Hrabe, N. (2022), Surface chemistry in Ti-6Al-4V feedstock as influenced by powder reuse in electron beam powder-bed fusion, Applied Surface Science, [online], https://doi.org/10.1016/j.apsusc.2022.154280, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932311 (Accessed December 21, 2024)