Microstructure and Mechanical Properties of Laser Cladding Carbon NanotubesToughened Fe-based Amorphous Coating

After the nickel-plated carbon nanotubes and iron-based amorphous powder were mixed by ball milling process, the coating was prepared on the steel plate by coaxial powder laser cladding method. The optimal ball milling time was determined, and the effect of the mass fraction of nickel-plated carbon nanotubes (0-1.00%) on the micro structure and mechanical properties of the coating was discussed. The results show that the proper ball milling time for mixing iron-based amorphous powder and nickel-plated carbon nanotubes was not longer than 30 min. The coatings all consisted of amorphous region, equiaxed dendritic region and columnar dendritic region; with increasing mass fraction of nickel-plated carbon nanotubes, the area fraction of amorphous phase in the coating decreased, and the size of the precipitated nanocrystals increased. The content of nickel-plated carbon nanotubes hardly affected the hardness of the columnar dendrite and equiaxed dendrite regions in the coating. With increasing mass fraction of nickel-plated carbon nanotubes, the average hardness of the amorphous region in the coating decreased from 1 615.0 HV to 1 464.3 HV, and the fracture toughness increased from 5.75 MPa·m^1/2 to 7.67 MPa·m^1/2.