Precipitation behavior of Al-Ti-O-N inclusions in unidirectionally solidified Fe-30mass%Ni alloy

The composition, size, morphology and distribution of the Al-Ti-O-N inclusions in the unidirectionally solidified Fe-30mass%Ni alloy were studied under the different solidification conditions as a function of solute contents which were controlled by using the CaO-Al2O3-TiOx-TiN slags. The TiOx-Al2O3 inclusions were observed in the initial contents of Ti = 20-11O and N = 60-130, while the TiN inclusions were observed in the initial contents of Ti = 700-1100 and N = 90-150 on mass ppm base. The Ti content and the size of the TiOx-Al2O3 inclusions increased with an increase in the cooling rate. The TiOx-rich TiOx-Al2O3 and the TIN inclusions were located in last stage of solidification in the interdendritic and the intercellular region. The precipitation of TIN and TIOx-Al2O3 inclusions was discussed by using the segregation models.