In Situ Reactive Formation of Mixed Oxides in Additively Manufactured Cobalt Alloy

Oxide-dispersion-strengthened (ODS) alloys have long been considered for high temperature turbine, spacecraft, and nuclear reactor components due to their high temperature strength and radiation resistance. Conventional synthesis approaches of ODS alloys involve ball milling of powders and consolidation. In this work, a process-synergistic approach is used to introduce oxide particles during laser powder bed fusion (LPBF). Chromium (III) oxide (Cr2O3) powders are blended with a cobalt-based alloy, Mar-M 509, and exposed to laser irradiation, resulting in reduction-oxidation reactions involving metal (Ta, Ti, Zr) ions from the metal matrix to form mixed oxides of increased thermodynamic stability. A microstructure analysis indicates the formation of nanoscale spherical mixed oxide particles as well as large agglomerates with internal cracks. Chemical analyses confirm the presence of Ta, Ti, and Zr in agglomerated oxides, but primarily Zr in the nanoscale oxides. Mechanical testing reveals that agglomerate particle cracking is detrimental to tensile ductility compared to the base alloy, suggesting the need for improved processing methods to break up oxide particle clusters and promote their uniform dispersion during laser exposure.

Automated summary

Oxide-dispersion-strengthened (ODS) alloys are being used in high temperature turbine, spacecraft, and nuclear reactor components due to their high temperature strength and radiation resistance. A process-synergistic approach using laser powder bed fusion (LPBF) is proposed to introduce oxide particles into ODS alloys. Microstructure analysis reveals the formation of nanoscale spherical mixed oxide particles and large agglomerates with internal cracks. Mechanical testing shows that cracking of agglomerate particles negatively affects the tensile ductility, suggesting a need for improved processing methods to promote the uniform dispersion of oxide particles during laser exposure.