Microstructure and fracture toughness of the FePSiB-based amorphous/nanocrystalline coatings

The effects of Cr and Nb additions on the microstructure and mechanical properties of the FePSiB coatings by using arc spraying process were investigated. By adjusting Cr and Nb contents, the glass formation ability and mechanical properties of the FePSiB coatings are effectively enhanced. The primary phase for the FePSiB coating is identified as nanoscale α Fe. With Cr and Nb additions, it promotes the finer α (Fe, Cr) nanocrystalline and a full amorphous phase concurrent structure. The onset crystallization temperature (Tx) increases from 545 °C to 572 °C. The fracture toughness is gradually increasing from 0.56 MPa m1/2 for the FePSiB coating to 0.79 MPa m1/2 for the FePSiBCrNb coating. The relationships between the glass-forming ability, the precipitated primary phase and the mechanical properties of the coatings are discussed in details.