The ordered structure of Cr2N precipitates in high-nitrogen austenitic steel was investigated utilizing high-resolution neutron powder diffractometry (HRPD). On the basis of the Rietveld refinement of neutron diffraction patterns, the ordered Cr2N superstructure was confirmed to be trigonal (space group P3̄1m), with lattice parameters a = 4.800 (4) and c = 4.472 (5) Å, as suggested in previous transmission electron microscopy studies [Lee, Oh, Han, Lee, Kim & Takaki (2005). Acta Cryst. B61, 137-144; Lee, Kim & Takaki (2006). Acta Cryst. B62, 190-196]. The occupancies of the N atoms in four crystallographic sites [1(a), 1(b), 2(d) and 2(c) Wyckoff sites] were determined to be 1.00(5), 0.0, 0.74(9) and 0.12(3), respectively, reflecting a partial disordering of N atoms along the c axis. The position of the metal atom was specified to be x = 0.346 (8) and z = 0.244 (6), corresponding to a deviation from the ideal position (x = 0.333 and z = 0.250). This deviation caused the (1/3 1/3 0)-type superlattice reflection to appear. A comparison between the ideal and measured crystal structures of Cr2N was performed using a computer simulation of selected-area diffraction patterns.
|Number of pages||8|
|Journal||Acta Crystallographica Section B: Structural Science|
|Publication status||Published - Dec 1 2006|
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)