The influence of alloying on properties of additively manufactured in-situ particle reinforced Fe-Ti alloys using reactive process atmospheres

In powder bed fusion – laser beam (PBF–LB), the process gas has been used to fabricate in-situ oxide dispersion strengthened (ODS) steels. Processing in reactive atmospheres, e.g. CO 2 and N 2 , causes process gas dissociation and absorption into the melt pool, thereby promoting nanoparticle formation. The intensity of the interaction depends on the atmosphere’s reactivity and the alloy composition. A strong interaction with the atmosphere is favorable to enhance nanoparticle formation. In this work, Fe-Ti model alloys with varying Ti content are processed via PBF–LB. The influence of the Ti alloying content on process gas uptake, nanoparticle, and slag layer formation is studied using Ar, CO 2, and N 2 atmospheres. Based on thermodynamic simulations, the resulting oxides are, depending on the Ti concentration, TiO or Ti 2 O 3 . The fraction and number density of nanoparticles are mainly determined by the processing gas and resulting O supersaturation in the melt pool. In-situ alloying and Ti-oxide nanoparticles additionally affect the grain structure of the processed materials and hence the hardness and creep performance of the materials. This work provides the fundament for targeted alloy design for advanced in-situ particle reinforced materials using reactive atmospheres in AM