Synthesis of nanocrystalline NiCrC alloy feedstock powders for thermal spraying by cryogenic ball milling

Kai Tao1) ,Xiang-lin Zhou1) ,Hua Cui2) ,Han-bin Chen1) ,Yong-bing Li1) ,and Ji-shan Zhang1) 1) State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China 2) School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China

摘 要：Nanocrystalline NiCrC alloy powders with a qualified particle size distribution for thermal spraying were synthesized using the cryogenic ball milling（cryomilling） method. The morphology,microstructure,size distribution,and phase transformation of the powders were characterized by scanning electron microscopy（SEM） ,laser scattering for particle size analysis,X-ray diffraction（XRD） ,and transmission electron microscopy（TEM） . After cryomilling for 20 h,the average grain size of the as-milled powders approached a constant value of 30 nm by XRD measurement. The average particle size slightly increased from 17.5 to 20.3 μm during the 20-h milling. About 90vol% of the powders satisfied the requirement for thermal spraying with the particle dimension of 10-50 μm,and most of the powders exhibited spherical morphology,which were expected to have good fluidity during thermal spraying. The Cr2O3 phase formed during the cryomilling process as revealed in the XRD spectra,which was expected to enhance the thermal stability of the as-milled powders during the followed thermal spraying or other heat treatment.

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