Microstructural Characterization and Prior Particle Boundary (PPB) of PM Nickel-Based Superalloys by Spark Plasma Sintering (SPS)

This research investigates the microstructure and defects of powder metallurgy (PM) nickel-based superalloys prepared by spark plasma sintering (SPS). The densification, microstructural evolution, and precipitate phase evolution processes of FGH96 superalloy after powder heat treatment (PHT) and sintering via SPS are specifically analyzed. Experimental results demonstrate that SPS technology, when applied to sinter at the sub-solidus temperature of the & gamma;' phase, effectively mitigates the formation of a prior particle boundary (PPB). Based on experimental and computational findings, it has been determined that the presence of elemental segregation and Al2O3 oxides on the surface of pre-alloyed powders leads to the preferential precipitation of MC-type carbides and Al2O3 and ZrO2 oxides in the sintering necks during the hot consolidation process, resulting in the formation of PPB. This study contributes to the understanding of microstructural modifications achieved through SPS technology, providing crucial information for optimizing sintering conditions and reducing the widespread occurrence of PPB, ultimately enhancing the material performance of PM nickel-based superalloys.

Automated summary

This research focuses on the microstructure and defects of spark plasma sintering (SPS) prepared powder metallurgy (PM) nickel-based superalloys. The study specifically analyzes the densification, microstructural evolution, and precipitate phase evolution processes of FGH96 superalloy after powder heat treatment (PHT) and sintering via SPS. The results indicate that the application of SPS technology at sub-solidus temperature effectively reduces the formation of a prior particle boundary (PPB), enhancing the material performance of PM nickel-based superalloys.