The feature and formation mechanism of inclusions in K4169 Ni-base superalloy by VIM

摘要

A method of electrolytic extraction in combination with in situ analysis was used to characterize the inclusions in the K4169 superalloy which was producted by VIM.This paper mainly depicted the phase compositions, morphologies and distribution of the inclusions and analyzed the formation mechanism of the inclusions.The results indicate that : The phase of inclusions in K4169 mainly include TiN,Al2O3, SiO2, TiO2, SiC and ' Mo-Ni-Fe-O' , ' Nb-Ni-O' , etc, compound oxide inclusions;Compound inclusions are developed by means of mutual collision or reaction in the process of VIM such as Al2O3-SiO2 and TiN-TiC;The inclusions of Al2O3-SiO2-CaO is more than 100 μm in size;TiN and TiC grow up by means of heterogeneous nucleation.Al2O3 provides heterogeneous nucleus for the growth of TiN and TiN provides heterogeneous nucleus for the growth of TiC;Most inclusions distributes in the shrinkage cavities which are located in the center of cast ingots.