Dispersion of Fine Primary Inclusions of Mg0 and ZrC)2 in Fe-10 Mass Pet Ni Alloy and the Solidification Structure

The homogeneous dispersion of primary inclusions of MgO and ZrO(2) was studied in an Fe-10 mass pet Ni alloy as a function of the holding time at 1873 K and the cooling rate. The spatial size distribution was eslimated from the planar size distribution obtained in a cross section by applying the Schwartz-Saltykuv transformation. It was found that the content of insoluble Mg or Zr estimated from the size distribution agreed with that obtained from chemical analysis. The influence on the solidification macrostructure such as columnar dendrite, equiaxed dendrite, and globular crystal of dissolved Mg or Zr and inclusion particles having them diameter of roughly 1(mu)m was investigated. The area fraction of globular crystals in the Mg deoxidation decreased with increasing dissolved Mg content (>30 mass ppm) in the presence of MgO particles. In the Zr deoxidation, however, globular crystals were only observed in the presence of ZrO(2) particles without respect to the presence of dissolved Zr.