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Fe-based bulk metallic glasses prepared by centrifugal casting method

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Author(s): R. Nowosielski | R. Babilas

Journal: Journal of Achievements in Materials and Manufacturing Engineering
ISSN 1734-8412

Volume: 48;
Issue: 2;
Start page: 153;
Date: 2011;
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Keywords: Amorphous materials | Bulk metallic glasses | Thermal and magnetic properties | Centrifugal casting

ABSTRACT
Purpose: The work presents a casting method, structure characterization and analysis of chosen properties of Fe-based bulk metallic glasses in as-cast state.Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4, Fe36Co36B19Si5Nb4, Fe43Co14Ni14B20Si5Nb4 metallic glasses in form of rings. The amorphous structure of tested samples was examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The crystallization behaviour of the studied alloys was examined by differential thermal analysis (DTA). The soft magnetic property examinations of tested materials contained initial magnetic permeability and measurements of magnetic permeability relaxation.Findings: The XRD and TEM investigations revealed that the studied as-cast bulk glassy samples in forms of ring were amorphous for all tested alloys. The SEM images showed that fractures of studied rings indicated two structurally different zones, which contained “river” patterns and “smooth” areas. The samples of studied alloys presented two stage crystallization process, which was observed for all tested rings with different thickness. The changes of crystallization temperatures versus the thickness of the glassy samples were stated. The magnetic permeability relaxation, which is directly proportional to the microvoids concentration in amorphous structure decreased with increase of sample thickness. These results could be assumed as the change of amorphous structure in function of thickness.Practical implications: The centrifugal casting method is very simple, useful and effective method to produce bulk amorphous materials in the form of rings or tubes.Originality/value: The preparation of bulk metallic glasses in the form of rings for three different Fe-based alloy systems is very important for the future progress in research and practical applications of iron-based bulk amorphous materials.

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Tangokurs Rapperswil-Jona

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