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From eutectic to peritectic: Effect of Ge on morphology, structure, and coarsening of Cr-Cr3Si alloys

Dorcheh, Ali S. ; Donner, Wolfgang ; Galetz, Mathias C. (2018)
From eutectic to peritectic: Effect of Ge on morphology, structure, and coarsening of Cr-Cr3Si alloys.
In: Intermetallics, 93
doi: 10.1016/j.intermet.2017.11.020
Article, Bibliographie

Abstract

The influence of germanium on microstructure, crystallography, and thermal stability of the eutectic Cr-Cr3Si alloy was investigated. Fine eutectic microstructures could be preserved but slightly degenerated when up to 2 at.% Si was substituted by Ge. A transition from eutectic to peritectic microstructure composed of primary dendrites and A15 Cr3Si matrix was observed when higher amounts of Ge were added. X-ray diffraction results showed no limit for substitution of Si and Ge in the studied composition range. The lattice parameter of both Cr solid-solution and A15 silicide increased with increasing the Ge/Si ratio. A macro was developed for the ImageJ program to automate the quantitative microstructural image analysis. Results showed that Ge addition increases the A15 phase fraction of the two-phase alloys. Microstructural investigations on annealed alloys at 1350 degrees C demonstrated that the coarsening of both binary Cr-Cr3Si and ternary Cr-Cr-3(Si, Ge) is interface-controlled. Although Ge addition to the eutectic alloy offered an isotropic microstructure, it decreased the thermal stability by degeneration of the lamellar structure.

Item Type: Article
Erschienen: 2018
Creators: Dorcheh, Ali S. ; Donner, Wolfgang ; Galetz, Mathias C.
Type of entry: Bibliographie
Title: From eutectic to peritectic: Effect of Ge on morphology, structure, and coarsening of Cr-Cr3Si alloys
Language: English
Date: February 2018
Publisher: DECHEMA Forschungsinstitut
Journal or Publication Title: Intermetallics
Volume of the journal: 93
DOI: 10.1016/j.intermet.2017.11.020
URL / URN: https://doi.org/10.1016/j.intermet.2017.11.020
Abstract:

The influence of germanium on microstructure, crystallography, and thermal stability of the eutectic Cr-Cr3Si alloy was investigated. Fine eutectic microstructures could be preserved but slightly degenerated when up to 2 at.% Si was substituted by Ge. A transition from eutectic to peritectic microstructure composed of primary dendrites and A15 Cr3Si matrix was observed when higher amounts of Ge were added. X-ray diffraction results showed no limit for substitution of Si and Ge in the studied composition range. The lattice parameter of both Cr solid-solution and A15 silicide increased with increasing the Ge/Si ratio. A macro was developed for the ImageJ program to automate the quantitative microstructural image analysis. Results showed that Ge addition increases the A15 phase fraction of the two-phase alloys. Microstructural investigations on annealed alloys at 1350 degrees C demonstrated that the coarsening of both binary Cr-Cr3Si and ternary Cr-Cr-3(Si, Ge) is interface-controlled. Although Ge addition to the eutectic alloy offered an isotropic microstructure, it decreased the thermal stability by degeneration of the lamellar structure.

Uncontrolled Keywords: Eutectic, Peritectic, ImageJ, Coarsening, Cr3Si, Chromium
Additional Information:

German Research Foundation (DFG) is thanked for the financial support of this work (GA-7704/1-1).

Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Structure Research
Date Deposited: 14 Sep 2020 07:22
Last Modified: 14 Sep 2020 07:22
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