Strength-ductility synergy in an additively manufactured oxide dispersion strengthened Inconel 718 superalloy at 650 °C

Abstract

The retention of dislocation cellular patterns (DCPs) in laser powder bed fusion (LPBF) processed metals offers a novel pathway for achieving strength-ductility balance in high-temperature applications. This study innovatively combines oxide dispersion strengthening (ODS) with tailored heat treatment to stabilize DCPs in Inconel 718 (IN718) superalloys. Through strategic introduction of yttrium oxide (Y₂O₃) nanoparticles (average diameter ≈40 nm) and optimized solution treatments (1200 °C for 5min/1 h), we resolve the inherent conflict between residual stress elimination and microstructure preservation in LPBF-fabricated components. The 5-min treated ODS alloy achieves exceptional synergy at 650 °C: yield strength maintains 600 MPa while ductility increases 45 % (from 20 % to 29 %) compared to as-built specimens. Crucially, our approach demonstrates two key innovations: 1) Y₂O₃ nanoparticles effectively pin dislocations movements, preserving DCPs structure against thermal coarsening; 2) Ultra-short heat treatment duration enables complete Laves phase dissolution without compromising dislocation network integrity. Microstructural analysis confirms that the stabilized DCPs-Y₂O₃ composite architecture facilitates simultaneous stress and strain accommodation. This work establishes a new paradigm for designing high-performance LPBF alloys through coupled process-microstructure optimization, particularly for aerospace components requiring elevated temperature mechanical stability.