The EU strategy for carbon neutrality has triggered extensive research in alloy development and production processes, pursuing high-performance materials for extreme conditions and sustainable components manufacturing processes. Additive manufacturing, especially the laser powder bed fusion (LPBF) process, offers an efficient solution for resources consumption and higher flexibility for topologically optimized functional components. However, LPBF of oxide dispersion strengthened (ODS) materials faces several pitfalls, making the exploitation of their outstanding creep performance in critical applications a persistent challenge. One of the main obstacles constraining this objective is incorporating these nanoceramic particles into the matrix with fair dispersion homogeneity while retaining the desired powder characteristics for LPBF processibility. Consequently, numerous powder feedstock preparation techniques have been introduced to achieve a homogeneous distribution in the composite powder.

In this work, different techniques for powder modification have been meticulously investigated, as a part of the EU Horizon-funded research project “TopAM”. The ex-situ approach for modifying 699XA Ni-based alloy with Y2O3 nanoparticles has been validated using high-energy ball milling, mechanical mixing, extensive mixing, and freeze granulation. Gas atomization reaction synthesis (GARS), fluidized bed reaction, and LPBF shielding gas reaction have been assessed for the in-situ formation of Y2O3 and TiN nanoparticles in the same alloy. After SEM characterization of the modified powder, LPBF processibility was evaluated aiming for the highest component density. The high-temperature mechanical properties and creep resistance were evaluated for the most promising conditions, along with TEM characterization of the nanoparticles.

Even though it was more challenging to produce a processable powder with a uniform dispersion of the nano oxide particles using the ex-situ processes, a higher volume fraction of reinforcement particles could be incorporated into the matrix. In contrast, the in-situ approach was one step ahead in terms of powder quality and process scalability, since the modification was conducted by modifying atomization gas. This distinction in nanoparticles’ size, number density, and coherency had a remarkable impact on the creep resistance, which significantly outperformed the unmodified counterparts in specific conditions.