Precipitation Behavior of TiN in Fe–10mass%Ni Alloy during Solidification and Isothermal Holding at 1 400°C

Abstract

The precipitation of TiN during solidification and holding at 1400°C has been studied in an Fe–10mass%Ni alloy as a function of initial contents of Ti and N and holding time. Dendritic and nondendritic (globular cell) zones are observed under the condition of the undercooling of 5 to 35°C. The number of particles per unit area, N_A, in nondendritic zone is significantly smaller than that in dendritic zone and the N_A values in both zones increase with holding time. The values for mean particle diameter, d_A, remain unchanged in dendritic zone with holding time, while the d_A values decrease with holding time in nondendritic zone. In dendritic and nondendritic zones, the degree of precipitation of TiN particles increase with increasing area fraction of solid, f_S, and the degree of precipitation depends on initial contents of Ti and N. The d_A value in nondendritic zone, which is independent of f_S, is larger than that in dendritic zone at zero holding time for a given initial content.