Design of novel NiSiAlY alloys in marine salt-spray environment:PartⅠ.Al-Si-Y and Ni-Si-Y subsystems

MCrAlY(M=Ni,Co,NiCo)alloys have been widely used as a bond layer for thermal barrier coatings(TBCs).However;oxides form discontinuously on MCrAlY surface in the marine environment since Cr_(2)O_(3)can react with NaCl and H_(2)O at temperatures above 500℃.Replacing Cr with other alloying elements(such as Si)might prevent severe salt-spray corrosion effectively.To save time and efforts in materials design of the Ni-Si-Al-Y system;we obtained the thermodynamic descriptions of the ternary compounds by coupling the CALPHAD(CALculation of PHAse Diagrams)approach and first-principles calculations.Seven and eighteen ternary compounds were evaluated and calculated in the Al-Si-Y and Ni-Si-Y systems;respectively.Phase diagrams of the two systems were depicted after a series of experimental Al/Ni-Si-RE(RE denotes rare earth elements,including La,Ce,Pr,Nd,Sm,Gd,Dy,Ho,and Er)systems being analyzed.It is found that the RE elements with the same reference states tend to form ternary compounds with the same crystal structures.The model-based descriptions are the basis for the research and development of novel NiSiAlY alloys in resisting high-temperature corrosion.