The location of interstitial carbon in austenite

(Received 18 October 1991, accepted in final form 3 January 1992)

Abstract
High resolution neutron time-of-flight powder diffraction patterns were obtained for the alloy Fe-13 wt. pct. Ni-1 wt. pct. C, in the austenitic phase. The interstitial site location of the carbon atoms was refined using Rietveld analysis and it was found that carbon resides primarily on the octahedrally coordinated interstices. Uncertainty in the refinement allows a maximum of 5 pct. of the total number of carbon atoms to occupy tetrahedral interstitial sites. The other refined structural and instrument parameters were determined to be relatively uncorrelated with these occupation fractions. The known total concentration of carbon in this alloy was not needed as a constraint on the carbon occupation, indicating that this refinement was extremely stable with regard to these parameters.