Solute segregation at 46.8°(111) twist grain boundary of a phosphorus doped Fe–2.3%V alloy

The Auger electron spectroscopy study on chemistry of the 46.8°(111) twist grain boundary of an Fe–2.3%V alloy showed an extended phosphorus enrichment at temperatures in range of 500 °C and 800 °C. Simultaneously, slight but nearly independent segregation of vanadium was also detected. The standard enthalpy and entropy of grain boundary segregation of phosphorus and vanadium were determined according to the Guttmann model of multicomponent interfacial segregation. Obtained data clearly show that this Σ = 19 coincidence boundary is special (i.e. low energy interface). The data also fit well with the predictive model of grain boundary segregation and confirm that phosphorus segregates interstitially at the grain boundary while vanadium substitutes iron atoms in the interface structure.