Influence of Metal-Layer Thickness on Annealing behaviors of a NiCoCrAl/YSZ Multiscalar Microlaminate produced by EB-PVD

One multiscalar microlaminate comprising the strong, thin layer stacks of NiCoCrAl/YSZ (ZrO2-8 wt.% Y2O3) and 5 thick tough phase layers of NiCoCrAl whose thicknesses ranged from 5 μm to 25 μm was fabricated by electron beam physical vapor deposition (EB-PVD). And then the foil was annealed at 1050 deg. C for 30 min. The tensile properties and microstructures of the microlaminate were examined. After annealing, the tensile properties of the microlaminate were greatly improved and the variation in microstructures of metal layers depended on their layer-thicknesses. When the layer-thicknesses were more than 20 μm, the annealed metal-layers were not recrystallized, and their grain structures as well as fracture morphologies had little changes comparing with those of the as-deposited metal layers. However, when the layer-thicknesses were less than 13 μm, recrystallization occurred in the metal-layers after annealing. Furthermore, the grain sizes, grain shapes and ductility of the recrystallized metal layers were dependant on their layer-thicknesses too.