Fabrication of FeAl(Cu) intermetallic coatings by plasma spraying of vacuum annealed powders

• FeAl(Cu) phase was stable during spraying due to congruent melting.
• Cu decreased the lattice parameter of FeAl.
• The lattice parameter of FeAl(Cu) decreased during spraying somewhat.
• Cu increased the hardness of FeAl due to solid solution strengthening.
• Cu decreased the exchange current density in acidic solution.

50Al-25Cu-25Fe (at.%) powders were milled for 0.5 h and subsequently annealed at 600, 750 and 900 °C for 0.5 h in a vacuum furnace. X-ray diffractometery (XRD) results revealed that FeAl(Cu) phase and unreacted Fe were seen after annealing at 600 and 750 °C while at 900 °C only FeAl(Cu) was formed. FeAl(Cu) powders were consolidated using air plasma spraying (APS) process. With increase of plasma power, the porosity content of the coating decreased from 33 to 8%. The FeAl(Cu) phase was stable during spraying while small amount of oxides were also formed. The coatings showed microhardness up to 487 HV and fracture toughness up to 4 MPa m0.5. The corrosion rate of the coatings in 0.5 M H2SO4 solution was lower than that of binary Fe-Al coatings reported in the literature.