effect on the mechanical properties of the material
Darja Steiner Petrovič (Author), Roman Šturm (Author), Iztok Naglič (Author), Boštjan Markoli (Author), Tomaž Pepelnjak (Author)

Abstract

The development of advanced materials and technologies based on magnetocaloric Gd and its compounds requires an understanding of the dependency of mechanical properties on their underlying microstructure. Therefore, the aim of the study was to characterize microstructural inhomogeneities in the gadolinium that can be used in magnetocaloric refrigeration systems. Microstructures of magnetocaloric gadolinium cylinders were investigated by light microscopy and FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy-dispersive X-ray Spectroscopy), and BSE (Back-scattered Electrons) in both the extrusion and the extrusion-transversal directions. XRD (X-ray Diffraction) analyses were performed to reveal the presence of calcium- and fluorine-based compounds. Metallographic characterization showed an oxidized and inhomogeneous microstructure of the cross-sections. The edges and the outer parts of the cylinders were oxidized more intensively on the surfaces directly exposed to the processing tools. Moreover, a significant morphological anisotropy of the non-metallic inclusions was observed. CaF inclusions act as active nucleation sites for internal oxidation. The non-metallic, Ca- and F-containing inclusions can be classified as complex calciumoxyfluorides. The solubility of Er and Yb in the CaF was negligible compared to the Gd matrix and/or the oxide phase. Lower mechanical properties of the material are a consequence of the lower structural integrity due to selective oxidation of surfaces and interfaces.

Keywords

Gadolinium;magnetocaloric;inclusions;selective oxidation;mechanical porperties;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL FS - Faculty of Mechanical Engineering
UDC: 620.1:67.017(045)
COBISS: 1206698 Link will open in a new window
ISSN: 1996-1944
Views: 220
Downloads: 59
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Other data

Secondary language: Slovenian
Secondary keywords: magnetokaloričnost;gadolinij;vključki;selektivna oksidacija;mehanske lastnosti;
Type (COBISS): Article
Pages: str. 1-14
Volume: ǂVol. ǂ9
Issue: ǂiss. ǂ5
Chronology: 2016
DOI: 10.3390/ma9050382
ID: 13582428
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