Effect of Alloying Elements on Grain Boundary Segregation of Nitrogen in α-Iron

Abstract

To clarify the effect of alloying elements (Me) on the grain boundary segregation behavior of nitrogen (N) in α-iron, the grain boundary segregation of N and alloying elements in the Fe–1.0 at.％Me–N (Me：Al, Ti, V, Cr, Mn, Nb or Mo) ternary system was thermodynamically evaluated using the parallel tangent law proposed by Hillert. In this study, the Gibbs energy of the liquid phase in the Fe–1.0 at.％Me–N ternary system was applied to that of the grain boundary. The calculations predicted co-segregation of N and alloying elements for alloys with Al, Ti, V, Cr or Nb additions. In contrast, co-segregation behavior was not predicted in the case of Mn or Mo addition. The tendency of co-segregation of N and alloying elements corresponded well with the formation tendency of metal nitrides.