Effect of solution and aging treatment on microstructure and high temperature mechanical properties of a new low-cobalt superalloy
A new type of low-cobalt superalloy was prepared by vacuum induction melting method.The effect of solution treatment and high-temperature aging treatment on microstructure and high-temperature tensile properties of the alloy was studied using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)analysis,X-ray diffraction(XRD)and electronic universal testing machine.The results show that the as-cast microstructure of the low-cobalt superalloy contains(γ+γ')eutectic structure,MC(1)carbides rich in W/Ta and MC(2)carbides rich in Ta/Hf,as well as two different sizes of γ'phase,Hf and Ta elements are significantly segregated between dendrites.With the increase of solution temperature and time,the(γ+γ')eutectic structure gradually dissolves back,element segregation is eliminated,and the content of small y'phase increases.The MC(1)carbides dissolve during the solution treatment and transform into W-rich M6C carbides at the edge.The Hf content in the MC(2)carbides increases while the Ta content decreases.After solution treatment at 1295 ℃ for 6 h and high-temperature aging at 1090 ℃ for 8 h,the volume fraction of eutectic structure in the alloy decreases to 1.3％,and it has good high-temperature tensile properties.
low-cobalt superalloysolution treatmenteutectic structurehigh temperature tensile
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