【摘 要】
：
The as-cast microstructure,element segregation and solidification behavior of a multi-alloyed superalloy ЭК151 have been investigated.The results show that the severe element segregation leads to the complicated precipitations at the inter-dendritic regio
【机 构】
：
Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110016, China;University of Scienc
论文部分内容阅读
The as-cast microstructure,element segregation and solidification behavior of a multi-alloyed superalloy ЭК151 have been investigated.The results show that the severe element segregation leads to the complicated precipitations at the inter-dendritic region,including η-Ni3(Ti,Nb),eutectic (γ + γ\') and Laves,which shows the characteristics of both Ti,Al-strengthened and Nb-strengthened alloys.Differential thermal analysis,heating and quenching tests reveal the solidification sequence as follows:Liquids → γ matrix → (Nb,Ti)C → η-Ni3(Ti,Nb)→ eutectic (γ+ γ\')→ Laves.The melting points are between 1250 and 1260 ℃ for (Nb,Ti)C,between 1200 and 1210 ℃ for η phase,between 1180 and 1190 ℃ for eutectic (γ + γ\') and Laves.γ\'initially precipitates from matrix at 1150 ℃ and achieves the maximum precipitation at 1130 ℃.According to the microstructure evolution captured during solidification and composition analysis by an energy dispersive spectrometer and electron probe microanalyzer,(Nb,Ti)/A1 ratio is put forward to explain the formation of η-Ni3(Ti,Nb) and eutectic (γ,+ γ\').The solidification of γ,matrix increased the Nb,Ti concentration in the residual liquids,so the high (Nb,Ti)/A1 ratio would result in the formation of η-Ni3(Ti,Nb);the precipitation of the phase consumed Nb and Ti and decreased the (Nb,Ti)/Al ratio in the liquid,which led to the precipitation of eutectic (γ+ γ\').Laves formed by the sides of η-Ni3(Ti,Nb) and in front of the eutectic (γ,+ γ,\') after Al,Ti were further depleted by the two phases and Cr,Co,Mo were rejected to liquids.
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