In-situ synthesis of Yttria-based precipitates and their effects on Fe12Cr6Al in laser powder bed fusion

To advance the suitability of FeCrAl alloys for nuclear applications, radiation damage resistance, creep resistance, corrosion resistance, and mechanical properties enhancement are essential. A promising approach is the introduction of a high density of nitride and oxide nanoprecipitates within the alloy matrix. This study aimed to explore the impact of in-situ formed nitride and oxide precipitates on the properties of Fe12Cr6Al alloy by using a nitrogen-rich atmosphere and incorporating nano-sized Y 2 O 3 (0.45 wt. %) during laser powder bed fusion (LPBF). As a result of adding Y 2 O 3 nanoparticles to the Fe12Cr6Al alloy, the grain size decreased from 70 μm to 40 μm, and the Al-O, Al-N, and Al-N-O precipitates were replaced by Y-O, Y-Al-O, and Y-N precipitates. Additionally, the nitrogen contents increased from 220 ppm to 470 ppm. The sample with Y 2 O 3 exhibited higher mechanical properties, with yield strength, tensile strength, and hardness (HV) increasing by 80 MPa, 112 MPa, and 23 HV, respectively. This study deviates from previous research on Y 2 O 3 -containing FeCrAl alloys by investigating the impact of in-situ synthesized Y-N nitrides on Fe12Cr6Al. The objective is to elucidate the combined effects of these precipitates on the properties of Fe12Cr6Al alloy in comparison to literature-reported oxide dispersion-strengthened (ODS) FeCrAl alloys, which were fabricated in an argon (Ar) atmosphere. • Al-O, Al-N, and Al-N-O nano precipitates were synthesized within the Fe12Cr6Al matrix under the N 2 atmosphere. However, adding Y 2 O 3 produced different types of nanoparticles, such as Y-O, Y-Al-O, and Y-N. • The sample without Y 2 O 3 exhibited a more columnar grain structure compared to the sample with Y 2 O 3 , and the grain size decreased from 70 μm to 40 μm with the addition of Y 2 O 3 . • The addition of Y 2 O 3 increased the oxygen content to 170 ppm and the nitrogen content to 470 ppm. • The as-built sample without Y 2 O 3 has a yield strength of 291 MPa, a tensile strength of 396 MPa, and an elongation of 7.8%. However, the as-built sample with Y 2 O 3 shows an increased yield strength of 371 MPa and tensile strength of 508 MPa, while the elongation decreased to 6.4%. Additionally, the hardness (HV) increased from 266 to 289 with the addition of Y 2 O 3 to Fe-12Cr-6Al.