On determining the surface segregation kinetics of Sb in binary and ternary Fe alloys during continuous annealing

In the present research, Sb surface segregation kinetics for Fe-(0.01/0.03)Sb and Fe-2Mn-(0.01/0.03)Sb at.% alloys were determined based on the modified Darken model and linear heating followed by isothermal annealing. The modified Darken model was used to evaluate the measured Sb segregation profile during continuous galvanizing heat treatments. Based on the kinetic analysis, increasing temperatures and isothermal holding times led to an increase in Sb surface segregation. Sb segregation was observed at the surface for both the Fe-xSb and Fe-2Mn-xSb alloys after annealing. It was found that Sb surface diffusion in the Fe-Sb alloys was faster than in the Fe-2Mn-Sb alloys, which was attributed to the crystal structure and the defect density in the matrix. The segregation rate was determined from the Darken curves and a higher segregation rate was observed in Fe-xSb alloys. The activation energy of Sb diffusion for the Fe-Sb and Fe-2Mn-xSb alloys was determined to be ∼ 193±18 kJ/mol, which is close to the activation energy of bulk Sb diffusion in α-Fe.