Study on the element segregation and Laves phase formation in the carbon nanotubes reinforced IN718 superalloy by laser cladding

Abstract

Electroless plating of Ni on the surfaces of multi-walled carbon nanotubes (MWCNTs) with two types of thicknesses were achieved. The structural evolution of MWCNTs in the laser cladding processing was investigated. It is observed that the MWCNTs can partially survive in the laser additive layers, but most of the tubes are unzipped, forming the graphene nano sheets (GNSs) and fragments. It is also found that the graphene fragments are inter-bonded with the neighboring ones, resulting in the formation of large porous carbon nano ribbons (CNRs). Due to the high surface area of the GNSs and CNRs, the element segregation and Laves phase formation in the laser cladded IN718 superalloy are suppressed significantly. With the thickness-increase of the Ni layer, the perfection of the graphene structure in the GNSs and CNRs is enhanced, and correspondingly, the depression effect on the element segregation and Laves phase formation of IN718 superalloy is improved.