Oxide dispersion strengthening (ODS) enhances the strength and high-temperature stability of metallic matrices by dispersing nanoscale oxides. Among these, Y2O3 is the most widely used due to its high thermal stability and low solubility, but conventional powder metallurgy suffers from particle agglomeration, inhomogeneous dispersion, high cost, and limited workability. To address these challenges, metal additive manufacturing (AM) has been proposed as an alternative. In this study, Y2O3 nanoparticles were uniformly dispersed and attached to hydrogenation-dehydrogenation (HDH) Ti-6Al-4V powder via a mechanofusion process, followed by dry coating of hydrophobic SiO2 nanoparticles to improve powder flow properties. Using the powder bed fusion (PBF) process, specimens were fabricated under optimized conditions within a volumetric energy density (VED) range of 49-400 J/mm3, applying a double scan-by-layer and double contour strategy, which enabled the production of specimens with relative densities exceeding 99.6%. Comprehensive evaluations of the fabricated specimens were conducted, covering surface analysis, nanoindentation, compressive testing, and high-temperature oxidation tests. While the addition of Y2O3 led to a slight decrease in room-temperature mechanical properties (a 1.3% reduction in nanoindentation hardness and a 18.6% reduction in compressive strength compared to the Y2O3-free specimen), it resulted in a marked improvement in high-temperature oxidation resistance (from 76.1 to 66.3 mg/cm2). This enhancement is attributed to the formation of a dense and stable protective layer composed of Y-Si-O complex oxides. This study demonstrates the applicability of surface-modified HDH Ti-6Al-4V powder in AM, while also identifying the advantages and limitations of implementing ODS mechanisms under PBF processing conditions.
The synergy between strength and ductility in metastable β titanium alloys is heavily governed by the activation of 332<113> twinning, yet the precise role of grain size in modulating these deformation dynamics remains elusive. In this study, the influence of grain size on the twinning behavior and resultant mechanical properties of a Ti-15Mo (wt
Focusing on the optimization of strength-ductility balance without rare-earth addition into Mg, four groups of comparative experiments are performed in this work. Instead of comparing or referring to any literatures concerning the commercial Mg brands, two binary model alloys including Mg–2.28 wt
There exhibit inhomogeneous microstructures and significant amounts of deteriorated long-striped Laves phases at weld joint, which markedly reduces the mechanical properties and deformation uniformity of the nickel base superalloy weld sheets. This greatly increases the forming difficulty of complex, ultra-thin nickel base superalloy components such as expansion joints and cooling tubes. Therefore, in this paper, a regulatory strategy has been discovered for achieving coordinated deformation and improving the plasticity of Inconel 718 (IN718) superalloy ultra-thin weld sheet (0.3 mm) by tailoring the Laves phases through appropriate heat treatment. Uniaxial tensile tests combined with Digital Image Correlation strain analysis were conducted to characterize mechanical behavior, while microstructural analysis elucidated the underlying fracture and strengthening mechanisms. The long-striped Laves phase readily undergoes stress concentration and fracture during tension, triggering microcracks that lead to premature failure of the weld sheet before heat treatment, with a tensile strength of 744.6 MPa and elongation of 18.6
