Spatially correlated structural disorder phenomena in zinc-rich alloys

A systematic reinvestigation of the zinc-rich region of the binary chromium-zinc system uncovers and identifies a structurally complex intermetallic γ-brass-type phase in brass-like systems, CrZn17-δ (-0.8 ≤ δ ≤ 1.7)by single crystal X-ray diffraction. The structure of CrZn17-δ represents a 2 x 2 x...

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1. Verfasser: Jana, Partha Pratim
Beteiligte: Harbrecht, Bernd (Prof. Dr.) (BetreuerIn (Doktorarbeit))
Format: Dissertation
Sprache:Englisch
Veröffentlicht: Philipps-Universität Marburg 2011
Chemie
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Zusammenfassung:A systematic reinvestigation of the zinc-rich region of the binary chromium-zinc system uncovers and identifies a structurally complex intermetallic γ-brass-type phase in brass-like systems, CrZn17-δ (-0.8 ≤ δ ≤ 1.7)by single crystal X-ray diffraction. The structure of CrZn17-δ represents a 2 x 2 x 2superstructure of a γ-brass-related structure with approximately 400 atoms in the cubic unit cell.A systematic investigation of chemical substitution in the Cr-Zn system has distinctly modified by replacing chromium and zinc by gold and has uncovered superstructure of γ-brass related phase ranging from Au2.6Cr6.4Zn91.7 to Au10.0Cr4.0Zn89.0.The structure of CrZn17-δ can also be distinctly modified by replacing Zn by Pd in this work and has uncovered a superstructure of γ-brass-related phase. The results of this study show that the phase ranges from Pd1.40Cr5.0Zn94.7 to Pd3.28Cr4.48Zn95.36. We attempted to study the influence of valence electron concentration (vec) on γ-brass type phases replacing Zn and/or Pd by Au (transition-element) in the parent Pd2+xZn11-x phase. Au2.89Pd3.44Zn19.68 represents the upper limit of Au substitution in the γ’-phase Pd2+xZn11-x. Further substitution of Au leads to 2 × 2 × 2 superstructures of γ-brass (γ’) with lattice parameters ranging from 1816.2(1) to 1816.6(2) pm (Pearson code cF402-cF405). In ruthenium-zinc binary system we have structurally identified the congener of hexagonal FeZn10, i.e.RuZn10. No ternary or pseudobinary systems have been reported to date. To the best of our knowledge, the hexagonal phases in the Au-Ru-Zn system reported herein are the only ternary variants of this family of intermetallic structures. Systematic studies of the ternary Au-Ru-Zn system in the range 0.014 ≤ xAu ≤ 0.148 and 0.914 ≤ xZn ≤ 0.76, reveals that ternary phases are isotopic with FeZn10.
DOI:https://doi.org/10.17192/z2012.0730