Thermal spraying NiCrAlY alloy powders prepared by close-coupled gas atomization

Abstract

NiCrAlY alloy powders used for the thermal spraying were fabricated by the closed-coupled gas atomization technology. The physical properties, particle size distribution, powder morphology, internal microstructure, and phase composition of the NiCrAlY alloy powders were investigated. The results show that, most of powders are spherical or nearly spherical particles, the particle size of 85% powders is less than 150 μm. The powder microstructures are mainly composed of dendrites and cellular crystals, and the solidification cooling rate of the powders with the particle size of 25～250 μm is about 4000～67000 K·s−1. The inner structure of the powders with the particle size less than 50 μm is dense, and a small number of particles with the particle size larger than 50 μm show the solidification shrinkage pore and hollow defects. There are Y and Si segregation in the crystal boundary and intracrystalline, and the powder phases are mainly composed of γ'-Ni3Al and γ-Ni solid solution phases.

Keywords

• close-coupled gas atomization
• nicraly alloy powders
• thermal spraying
• microstructure
• powder properties