Interaction of Ta and Cr on Type-I hot corrosion resistance of single crystal Ni-base superalloys

Type-I hot corrosion behaviour of single crystal Ni-base superalloys with different Cr and Ta contents in sodium sulphate (Na2SO4) at 900 °C and 950 °C in static air were investigated using the “deposit recoat” method. It was shown that, increasing corrosion temperature shortened the incubation period. Loss of hot corrosion resistance causing by Cr reduction cannot be compensated by increasing Ta content. The effect of Ta addition on hot corrosion resistance can be described by introducing the quantitative parameter Ta/Cr (wt.%) ratio. Interaction of Cr, Ta and temperature on hot corrosion behaviour was discussed in detail in the present paper.