Effect of Pt pinning wires on aging microstructure of surface layer of single crystal superalloy turbine blade
Effect of Pt pinning wires on as-cast microstructure,solidification characteristics and aging microstructure of surface layer of single crystal superalloy hollow turbine blades was studied using optical microscope(OM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)analysis and differential scanning calorimetry(DSC).The results show that during the directional solidification process,Pt wires are melted in the superalloy melt,leading to an increased tendency for alloy solidification segregation at the pin.During the aging treatment at 1100 ℃ for different time,recrystallization occurs at the pins.The γ'phase rafting becomes more severe when the aging time exceeds 500 h,and the topologically closed phase(TCP)precipitates in the pins.During the directional solidification process,the non-equilibrium solidification shrinkage between the blades and the mold shell,as well as the cleaning process of the mold shell,lead to the deformation of the pin,thereby inducing recrystallization during the aging treatment.The enrichment of Pt in the pin alloy during long-term aging leads to the enrichment of W,Re,and other elements in its matrix structure,promoting the precipitation of TCP phase.Due to the low Pt content in the surface alloy of the turbine blade corresponding to the pins position,there is no TCP phase formed.
single crystal superalloyPt wireagingrecrystallizationTCP phase
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