Computer Simulation of Spinodal Decomposition in Fe–Cr–Ni Ternary Alloys and Fe–Cr–Mo–Ni Quaternary Alloys

Abstract

Numerical simulations of phase separation in Fe–Cr–Ni ternary alloys and Fe–Cr–Mo–Ni quaternary alloys similar to ferrite phases in duplex stainless steels were performed with using of the Cahn-Hilliard equations. A new numerical model based on the Gauss-Seidel and Newton-Raphson methods were utilized to obtain efficient and accurate solution.
We obtained that small addition of Ni retard phase separation of Cr in Fe–Cr–Ni ternary alloys. The simulation results on behavior of Mo and Ni in Fe–Cr–Mo–Ni ternary alloys were quite similar to Mo in Fe–Cr–Mo and Ni in Fe–Cr–Ni ternary alloys. It is known that behavior of Mo or Ni along the trajectory of the peak tops of Cr concentration is determined by the sign of second derivative of Cr and Mo or which of Cr and Ni. The effect of Ni on the peak height of Cr in Fe–Cr–Mo–Ni quaternary alloys is similar to which in Fe–Cr–Ni alloys.
Numerical simulation results on the variation of peak height of Cr are qualitatively in good agreement with those obtained by the Atom-Probe-FIM.