Spray forming of Zircaloy-4

Zircaloy-4 was spray formed using an induction skull melting/spray atomization and deposition unit. The microstructure and phase composition of the spray formed Zircaloy-4 bulk materials and oversprayed Zircaloy-4 powders were investigated. The microstructure of the spray formed Zircaloy-4 bulk materials was found to be Widmanstätten α plates precipitated out from equiaxed β grains, with evident microstructure refinement in terms of the sizes corresponding to equiaxed β phase grains and the α plates, respectively. The microstructure of oversprayed Zircaloy-4 powders was also revealed to be Widmanstätten α plates precipitated out from equiaxed β grains, in contrast with the dendritic structure generally reported for oversprayed powders. These microstructure characteristics were discussed in light of the thermal history experienced by the powders and the deposit. Finally, the density and hardness of spray formed Zircaloy-4 were also characterized, indicating that spray forming had little effect on these properties for Zircaloy-4 studied herein.