Particle-Stimulated Nucleation (PSN) in the Co–28Cr–5Mo–0.3C Alloy

Abstract

The present work is aimed at refining the grain size in the Co–28Cr–5Mo–0.3C (wt%) cast alloy using particle-stimulated nucleation (PSN) of recrystallization. It is pointed out that PSN resulted in considerable grain refinement (≈80%) of the as-cast structure, leading to an increased yield and tensile strength (around 30%). Partial solutionizing is associated with the formation of γfcc and athermal martensite. During PSN, the intensity of the hexagonal close-packed (hcp) phase increases due to the formation of isothermal martensite. It appears that new dynamic recrystallized (DRX) grains are formed around coarse undissolved particles (≈10 μm in size), especially where these particles are present in large clusters. The high-resolution TEM image shows the formation of heavily faulted regions and subgrains, with maximum misorientation near the carbides providing the driving force for the nucleation of new grains.

Keywords

• CoCrMoC alloy
• particle-stimulated nucleation
• grain size
• martensite