Solubility products of VS and NbS in iron alloys

Abstract

Solubility of sulfur in Fe-V and Fe-Nb alloys was experimentally determined using a diffusion couple technique. Solubility product of VS and NbS in ferrite (α) and austenite (γ) phases were determined as log(mass%V)(mass%S)α=4.76-10100/T, log(mass%V)(mass%S)γ=4.90-11 000/T and log(mass%Nb)(mass%S)γ=4.70-10 500/T in the temperature range from 1 523 to 1 573 K. A thermodynamic analysis was also carried out to evaluate the formation energy of VS and NbS. The estimated formation energy of VS and NbS are δGVSsulfide=-263 100+61.0T (J/mol) and δGNbssulfide=-260 800+68.4T (J/mol), respectively. © 2009 ISIJ.