This work described an experimental investigation on the recrystallization behaviors of the hot-rolled particle strengthened W (PSW) material. Upon annealing, the three processes, that is, recovery, recrystallization and grain growth, proceed in a discontinuous fashion for our PSW material, and two or more processes could simultaneously occur in local regions. At an annealing temperature spanning from 1300 °C to 1500 °C, recovery is in the dominant position which is verified by deformed grains over half of the whole, accompanying with a gentle decrease in hardness. Meanwhile, recrystallization nucleation, primary recrystallization and abnormal grain growth is identified at 1300 °C, 1400 °C and 1500 °C, respectively. Further increasing the annealing temperature to 1600 °C and 1700 °C, normal grain growth takes precedence over recovery, along with a marked reduction in hardness. TEM observations show that owing to microstructural heterogeneity induced by particle dispersion, local regions have an advantage in terms of strain energy storage over other regions during hot rolling, enabling a preferential recrystallization nucleation at 1300 °C; whereas nanosized TiC particles are capable of inhibiting grain growth at elevated temperature, and thus retard the recrystallization rate. In addition, our as-rolled PSW material exhibits a different texture, and the dominant α-fiber of {100}〈011〉 and {112}〈1−10〉 transforms into γ-fiber texture of {111}〈011〉 and {111}〈−1−12〉 during recrystallization.
Oxide dispersion strengthened (ODS) nickel (Ni)-based superalloys are advanced materials known for their outstanding tensile and creep performance at temperatures exceeding 1000 °C. Nevertheless, their conventional synthesis presents a longstanding challenge in cost-effectively producing intricate components for critical applications. In this work, electrostatic self-assembly (ESA) of powders with the laser powder bed fusion (LPBF) process have been successfully combined to produce yttria ODS Inconel 718 (IN718) alloy for the first time. The approach has demonstrated a significant contribution of yttria to the strength of IN718 after the solid solution heat treatment, as evidenced by ≈50% improvement in room temperature yield strength with a 0.5 wt.% yttria addition. The addition of yttria by this process leads to a heterogeneous microstructure. This heterogeneous microstructure comprises two distinct grain areas with varying amounts of yttria nanoparticles and dislocation storage. It has been shown that the yield strength increase can be predicted by the combination of both Y 2 O 3 dispersion strengthening and dislocation strengthening mechanisms. These findings offer an effective approach to tailor heterogeneous microstructures, unlocking new opportunities for cost-effectively producing high-performance ODS Ni-based superalloy products with excellent mechanical properties.
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