Nitride precipitation on particles in Fe-10mass%Ni alloy deoxidized with Ti, M(M=Mg, Zr and Ce) and Ti/M

Abstract

The precipitation of nitrides on deoxidation particles in an Fe-10mass%Ni alloy containing 30-130 ppmO and 14-22 ppm N has been studied in the experiments where an alloy was deoxidized with Ti, M (M=Mg, Zr and Ce) and Ti/M at 1 600°C and then cooled to 1 200°C, followed by holding for 0 and 60 min before quenching. The total number of particles above 0.1 μm remains almost constant except in Ti deoxidation, but the proportion of cubic particles which correspond to nitrides and oxide-nitrides increases during holding at 1 200°C in Ti, Zr, Ti/Mg and Ti/Zr deoxidations. In 0.05 % (initial amount) Ti deoxidation, the number of TiN and TiN+TiO x particles increases during holding. In 0.03%Ti/0.1%Mg deoxidation, the number of TiOx-TiN particles decreases and the number of MgO-TiN and MgO-Ti(O, N) particles increases during holding due to the reduction of TiO x with soluble Mg. In 0.03%Ti/0.04%Zr deoxidation, the number of ZrO 2 particles significantly decreases during holding due to the precipitation of TiN and ZrN on Zr oxides and formation of Zr(O, N)-Ti(O, N) particles. In the cases of Ti/0.08%Zr and Ti/0.12%Ce deoxidations, most of particles at 0 and 60 min of holding are ZrO 2 and Zr(O, N) and Ce 2O 3 oxides, respectively, because the FeO-TiO x oxide in particles is reduced completely by dissolved Zr and Ce. © 2009 ISIJ.