60 NiTi(60wt%Ni-40wt%Ti)alloy presents higher hardness,high elastic modulus,good abrasion perform-ance and excellent corrosion resistance,making it suitable for various applications in different fields.This paper investigated the microstructure and phase composition of NiTi alloy coating on 316L stainless steel prepared by laser cladding.It shows that the main alloying elements Fe and Cr in the substrate are significantly doped into the cladding coating,which obviously affect the microstructure and properties of Ni-Ti coating.The main phases in the coating are NiTi and Ni3Ti phases.Increase the content of Ni can inhibit the precipitation of NiTi2.First-principles calculation based on density functional theory was used to study the phase preference and site preference occupa-tions of the alloying elements Fe and Cr from substrate in NiTi and Ni3Ti phases.The microstructure and phase composition of the coatings were investigated as well.The results show that,NiTi and Ni3Ti are the major phases in the coating.Both Fe and Cr atoms prefer to substitute Ni atom in the NiTi(B2)crystal structure.However,in the Ni3Ti crystal structure,each Ni and Ti atom has two different crystal positions,Fe atom prefers to substitute posi-tion Ni-1 and Cr atom prefers to substitute position Ni-2 instead.Combined the experiment and calculation results,the major phases in the coatings after element doping are supposed to be Ni5Ti8Fe2Cr and Ni9Ti4Fe2Cr.
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