Microstructure evolution of Ni-Mo-Fe-Si quaternary metal silicide alloy composite coatings by laser cladding on pure Ni

Abstract

Three Ni-Mo-Fe-Si quaternary metal silicide alloy coatings were fabricated on the pure nickel plate by laser cladding. The mixed powders of different compositions of Ni, Mo, Fe, and Si elements were employed as the cladding materials. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and electron backscattering diffraction were adopted to investigate the microstructure. The wear properties of three coatings were evaluated under large contact load at room-temperature, dry-sliding wear-test conditions. Results indicated that the phases of three coatings were Ni3Si2/Ni2Si/Mo2(Ni, Fe)3Si as matrix phases and Mo2(Ni, Fe)3Si/Mo6Ni5Si2 as primary phases, Ni3Si2/γ-(Ni, Fe)+Ni31Si12/γ-(Ni, Fe) as matrix phases and Mo2(Ni, Fe)3Si/Mo6Ni5Si2 as primary phases, and γ-(Ni, Fe) as the matrix phase and Mo2(Ni, Fe)3Si as the primary phase for Coatings 1, 2, and 3, respectively. For quaternary metal silicide alloys, ideal configurational entropy of Ni-Mo-Fe-Si alloys increased as the composition tends to equimolar ratio. High entropy will reduce the kinds of phases and be easy to form phases with simple structure in Ni-Mo-Fe-Si coatings. The solubility of Fe element in Mo2(Ni, Fe)3Si phase is high because of the its replacement of Ni in this complicate phase. The average micro-hardness for Coatings 1, 2, and 3 is 987 HV, 977 HV, and 734 HV, respectively. Three coatings exhibited outstanding wear resistance due to a combination of excellent strength and toughness.