The use of secondary ion mass spectrometry and analytical electron microscopy for the determination of the distribution of sulfur in thin-film bicrystals of iron-sulfur alloys with small and large angle (001); twist boundaries

The segregation of sulfur in the vicinity of small and large angle (near {dollar}Sigma{dollar} = 5) (001) twist boundaries of thin-film bicrystals of Fe-S alloys was studied and quantified using the complimentary techniques of Secondary Ion Mass Spectrometry (SIMS) and Analytical Electron Microscopy (AEM).; In the case of the small angle twist boundaries, the difference in the S content between the observed {dollar}langle 110rangle{dollar} and {dollar}langle 100rangle{dollar} dislocation networks was found to be insignificant. Consideration of the diffusion length of S in Fe and speculation upon the effects of the kinetics of segregation (to both grain boundary interfaces and free surfaces) suggested that the bulk solute content of the Fe-S bicrystals was rapidly depleted resulting in a significantly reduced equilibrium enrichment ratio for both of the observed dislocation networks.; For the case of the large angle (near {dollar}Sigma{dollar} = 5) twist boundary, the concentration of S within the observed {dollar}langle 210rangle{dollar} dislocation networks was found to be approximately 64% higher than the {dollar}langle 310rangle{dollar} networks. In addition, the S content of the {dollar}langle 210rangle{dollar} networks was nearly seven times greater than the S content found in the dislocation networks of the small angle twist boundaries. The results suggest that the extent of segregation increases as the boundary misorientation angle increases from the small to the large angle regime.; The SIMS depth profile analyses of ion implanted quantification standards revealed that severe channeling occurred when the specimens were implanted with S. It was argued that only the amorphous peak of the ion implant could make a significant contribution to the overall concentration of S in the vicinity of the grain boundary of the implanted bicrystal specimens. Confirming this argument was the observation that the relative difference in the peak concentrations at the grain boundary for the nonimplanted small angle twist boundary and the implanted small angle twist boundary was consistent with the concentrations found for the amorphous peaks of the severely channeled S implant standards.; Based upon the SIMS depth profile analyses, the thickness of a nonimplanted small angle grain boundary was calculated to be 25 A. The value is consistent with measurements of other researchers.