Research Information System
Materials Science and Engineering: A, vol.923, 2025 (SCI-Expanded)
In this study, a new grade of oxide dispersion strengthened (ODS) Inconel 625 (IN625) alloy having the composition of 0.3 wt% Y2O3 – 0.4 wt% Hf – IN625 has been developed and produced by laser powder bed fusion (L-PBF). Production parameters have been determined for standard (i.e. non-ODS) and ODS-IN625 alloys to yield >99.9 % densification. Microstructural analyses reveal similar texture along <001> while a larger but homogenous strain distribution exist in ODS-IN625. Nano-particles are determined to be mostly Y-Hf-O and Y2O3 with an average size of 30 ± 18 nm and 2.2 ± 1.1 × 1013 m-2 areal fraction. Tensile tests at room temperature (RT) and 700 °C demonstrate superior mechanical properties of ODS-IN625, particularly at elevated temperatures. While the yield strengths of standard and ODS-IN625 alloys are similar (∼680 MPa), ductility of ODS-IN625 is slightly larger at RT. However, the yield strength of ODS-IN625 increased by 7.4 %, reaching ∼580 MPa, compared to the standard IN625, which has a yield strength of ∼540 MPa at 700 °C. More notably, the ductility of ODS-IN625 shows a remarkable improvement, increasing from ∼12 % in the standard IN625 to ∼22 %, representing an increase of more than 80 %. Detailed microstructural analyses on the fracture surfaces of the ODS-IN625 alloys exhibit submicron dimples, as well as an extensive amount of dislocation loops, Lomer-Cortrel (L-C) locks, and stacking fault tetrahedra. Nano-oxides were determined to be responsible for the dislocation wall structure and dislocation distribution which in turn improves the mechanical properties. This study sheds light on tailoring the strength-ductility balance in IN625 alloys by introducing the nano-oxide particles and perceiving the mechanism of this improvement.