X-Ray Powder Diffraction Evidence for the Incorporation of Tungsten and Molybdenum Into M sub 23 C sub 6 Extracted From High-Temperature Alloys

• Published in: Journal of materials science Vol. 17; no. 10; pp. 3057 - 3065
• Main Authors: Franck, F J, Tambuyser, P, Zubani, I
• Format: Journal Article
• Language: English
• Published: 01.10.1982
• ISSN: 0022-2461

X-ray powder diffraction patterns of M sub 23 C sub 6 where M = (Cr, Mo) and M = (Cr, tungsten) have been recorded accurately using a focusing Guinier camera and a diffractometer. The improved resolution of the modern focusing diffraction equipment made it possible to detect new features in the powder diffraction patterns, showing that M sub 23 C sub 6 carbides extracted from W- and Mo-containing alloys (Ni-base superalloys) differ from pure Cr sub 23 C sub 6 and (Cr, Fe) sub 23 C sub 6 met in more conventional stainless steels. The distinctions concern the lattice parameters and the intensities of specific diffraction max. These differences can be explained in terms of the theoretical considerations of Goldschmidt who predicted that W and Mo, when incorporated in Cr sub 23 C sub 6 , will preferentially occupy specific positions in the unit cell. Diffraction intensity calculations confirm that the introduction of W and Mo atoms on these particular positions will modify the diffracted intensities in the same way as was observed experimentally. 18 ref.--AA