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Complex intermetallics in Al-Ni-Cr alloys

Wojciech Kowalski 1Benjamin Brushko 2Marian Surowiec 1Dmytro Pavlyuchkov 2,3

1. University of Silesia, Institute of Materials Science, 12, Bankowa Str., Katowice 40-007, Poland
2. Research Centre Jülich, Institute of Solid State Research (IFF), Jülich, Germany
3. Institute for Problems in Materias Science (IPMS), 3, Krzhizhanivsky Str., Kiev 03680, Ukraine

Abstract

Quasiperiodic phases with symmetries forbidden by classic crystallography have been observed in systems of aluminum with transition metals. The paper presents investigations of the Al-Ni-Cr and Al-Pd-Cr phase diagrams by scanning and transmission electron microscopy, differential thermal analysis and X-ray powder diffractometry. In the Al-Ni-Cr four ternary crystalline phases were formed close to the compositions of binary m-Al4Cr and h- Al5Cr. One of them, designated as z with hexagonal structure, was formed in a wide range of composition between Al82Ni2Cr16 and Al71Ni11Cr18. The second phase z1, was found in samples containing slightly more aluminum. Electron diffraction patterns shows that the c parameter was the same as in z, but the a parameter was √3 larger. Another phase, designated as f, was found around Al79Ni9Cr12. It exhibits a monoclinic structure and it incongruently melts at 835°C. The fourth ternary phase was found in Al76Ni2Cr22 alloy annealed at 1000°C. We designate it as e. It was found to be only stable at elevated temperatures and not observed in the same sample at 900°C. The structure of the e phase was found to be orthorombic.

 

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Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Wojciech Kowalski
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-22 12:39
Revised:   2009-06-07 00:44