Experimental Determination and Atomistic Simulation on the Structure of FeZn 13
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ection I: Basic and Applied Research
Experimental Determination and Atomistic Simulation on the Structure of FeZn 13 Y. Liu, X.P. Su, F.C. Yin, Z. Li, and Y.H. Liu
(Submitted April 7, 2008; in revised form July 15, 2008) By X-ray diffraction combined with Rietveld structure refinement, the crystal structure of FeZn13 was determined experimentally in this study. The results indicated that the structure of FeZn13 is monoclinic and the lattice parameters are a = 1.3408 nm, b = 0.7605 nm, c = 0.5074 nm, and b = 127.206°. It was confirmed that Fe atoms occupy the 2c position (0, 0, 0.5) in space group C2/m, and the coordinates of Zn atoms at the Zn(1) position are (0.114, 0.5, 0.293), which supports the results from Belin et al. (Acta Cryst. C 56:267, 2000). In addition, an atomistic calculation was carried out to determine the crystal structure based on the interatomic potentials obtained using the lattice inversion method, and Fe atoms are substituted by Zn atoms in the narrow solubility range of FeZn13, which is the fundamental for studying the solubility and site preference of alloying elements of FeZn13. Good agreement between the experimental results and the theoretical calculations was achieved.
Keywords
atomistic simulations, crystal structure, intermetallics, X-ray diffraction (XRD)
1. Introduction Among the four intermetallics in the Fe-Zn binary system, the f phase, FeZn13, has been studied most intensively due mainly to the critical role it plays in the galvanizing of reactive steels containing Si.[1-3] The Si-containing steels experience uncontrolled attack from the molten Zn in hot-dip batch galvanizing; this results in excessively thick coatings with an unattractive gray appearance. This phenomenon is often referred to as the ‘‘Sandelin effect.’’[4] To explore the mechanism of this phenomenon, the investigation of solubility and site preference of alloying elements such as Si, Ni, Bi, etc. in FeZn13 is necessary. However, the crystal structure of FeZn13 and, in particular, the coordinates of the atoms need further clarification. Go¨tzl et al. first determined the lattice parameters of FeZn13 in the alloy systems (Mn, Fe, Co)-Zn and proposed that the possible space groups were C2, Cm, or C2/m.[5] Later, Brown[6] described the structure concretely and postulated the probable position for the transition metal atoms (Fe, Mn, Co). In 1979, Gellings and his collaborators characterized all Fe-Zn intermetallics including FeZn13.[7] Their results agreed well with those of Brown.[6] However, Gellings et al.
Y. Liu, X.P. Su, F.C. Yin, and Z. Li, Key Laboratory of Materials Design and Preparation Technology of Hunan Province, School of Mechanical Engineering, Xiangtan University, Hunan, P.R. China; Y.H. Liu, Teck Cominco Metals Ltd., Product Technology Centre, 2380 Speakman Drive, Sheridan Science and Technology Park, Mississauga, ON, Canada L5K 1B4. Contact e-mail: [email protected].
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chose a different a axis with a smaller b angle, resulting in a very different set of parametric values. In 2000, Belin and his
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