Technische Universität Dresden
A Case Study of Complex Metallic Alloy Phases: Structure and Disorder Phenomena of Mg-Pd Compounds
Abstract
dc:description.abstractThe phase diagram of the Mg-Pd system was redetermined in the range from 50 at. % Mg to 100 at. % Mg. It contains several intermediate phases with some of them being complex metallic alloy phases (CMAs), i.e., characterized by (i) giant unit cells with more than hundred atoms, (ii) inherent disorder, (iii) the presence of a cluster substructure. Phase fields and heterogeneous equilibria of the intermediate phases β- Mg6Pd, γ-Mg57Pd13, δ-Mg56.4Pd13.6, ε-Mg306Pd77, ζ-Mg64Pd17, η-Mg3Pd, θ-Mg5Pd2, ι- Mg2Pd and κ-MgPd were determined. The first five phases are CMAs with Mackay clusters as fundamental structural units. The crystal structure of the most magnesium-rich compound β-Mg6Pd was redetermined. It was found to be more complicated than previously thought due to correlated disorder of only two atom sites in the cubic unit cell. The γ-, ε- and ζ-phases form in a small window of temperature (50 oC) and composition (3 at. %) close to 80 at. % Mg. A new structure type was assigned to Mg3Pd (Cu3P, P63cm). The single phase field of the θ-phase is caused by constitutional vacancies. The new ι-phase crystallizes with NiTi2 structure-type.
Degree
thesis:*- Level thesis:degree_level
- thesis.doctoral
- Grantor dc:publisher
- Technische Universität Dresden
- Year
- 2009
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Makongo Mangan, Julien Pierre Amelie
- Contributors dc:contributor
-
- Kniep, Rüdiger
- Ruck, Michael
- Harbrecht, Bernd