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The effect of the thermal decomposition reaction on the mechanical and magnetocaloric properties of La(Fe,Si,Co)13

Löwe, Konrad ; Liu, Jian ; Skokov, Konstantin ; Moore, James D. ; Sepehri-Amin, Hossein ; Hono, Kazuhiro ; Katter, Matthias ; Gutfleisch, Oliver (2012)
The effect of the thermal decomposition reaction on the mechanical and magnetocaloric properties of La(Fe,Si,Co)13.
In: Acta Materialia, 60 (10)
doi: 10.1016/j.actamat.2012.04.027
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

We report on the influence of the Co content in the magnetocaloric system La(Fe,Si,Co)13 on the thermal decomposition (TD) reaction, and subsequently on the magnetocaloric properties. In the course of the TD reaction, the magnetocaloric La(Fe,Si,Co)13 phase reversibly decomposes into α-Fe(Co,Si) and the intermetallic LaFeSi phase, thus enhancing the mechanical properties and therefore the machinability of the compound. The addition of Co significantly speeds up the reaction kinetics. The optimum temperature range for the TD reaction was determined to be 973–1073 K, with the lower and upper limit at 873 K and 1173 K, respectively. With electron microscopy a lamellar microstructure has been found in the decomposed state, indicating a eutectoid-type phase reaction. The width of the lamellae is ∼26 nm in LaFe12Si and decreases with increasing Co content. Three-dimensional atom probe (3DAP) measurements show the enrichment of Co and Si in LaFeSi lamellae. We conclude that the addition of Co somehow decreases the lamellar spacing, which is the main reason for the enhanced TD kinetics. Finally, it is interesting to note that the highly ordered nano-scale mixture of strongly ferromagnetic α-Fe(Co) with the non-ferromagnetic phase induces a significant increase in coercivity, Hc. The shape anisotropy of the thin α-Fe(Co) lamellae yields a semi-hard permanent magnet with a coercivity of ∼100 A cm−1.

Typ des Eintrags: Artikel
Erschienen: 2012
Autor(en): Löwe, Konrad ; Liu, Jian ; Skokov, Konstantin ; Moore, James D. ; Sepehri-Amin, Hossein ; Hono, Kazuhiro ; Katter, Matthias ; Gutfleisch, Oliver
Art des Eintrags: Bibliographie
Titel: The effect of the thermal decomposition reaction on the mechanical and magnetocaloric properties of La(Fe,Si,Co)13
Sprache: Englisch
Publikationsjahr: Juni 2012
Verlag: Elsevier Science Publishing
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Acta Materialia
Jahrgang/Volume einer Zeitschrift: 60
(Heft-)Nummer: 10
DOI: 10.1016/j.actamat.2012.04.027
Kurzbeschreibung (Abstract):

We report on the influence of the Co content in the magnetocaloric system La(Fe,Si,Co)13 on the thermal decomposition (TD) reaction, and subsequently on the magnetocaloric properties. In the course of the TD reaction, the magnetocaloric La(Fe,Si,Co)13 phase reversibly decomposes into α-Fe(Co,Si) and the intermetallic LaFeSi phase, thus enhancing the mechanical properties and therefore the machinability of the compound. The addition of Co significantly speeds up the reaction kinetics. The optimum temperature range for the TD reaction was determined to be 973–1073 K, with the lower and upper limit at 873 K and 1173 K, respectively. With electron microscopy a lamellar microstructure has been found in the decomposed state, indicating a eutectoid-type phase reaction. The width of the lamellae is ∼26 nm in LaFe12Si and decreases with increasing Co content. Three-dimensional atom probe (3DAP) measurements show the enrichment of Co and Si in LaFeSi lamellae. We conclude that the addition of Co somehow decreases the lamellar spacing, which is the main reason for the enhanced TD kinetics. Finally, it is interesting to note that the highly ordered nano-scale mixture of strongly ferromagnetic α-Fe(Co) with the non-ferromagnetic phase induces a significant increase in coercivity, Hc. The shape anisotropy of the thin α-Fe(Co) lamellae yields a semi-hard permanent magnet with a coercivity of ∼100 A cm−1.

Freie Schlagworte: Magnetocaloric, La(Fe,Si)13, Thermal decomposition, Ageing, Microstructure
Fachbereich(e)/-gebiet(e): 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Funktionale Materialien
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft
11 Fachbereich Material- und Geowissenschaften
Hinterlegungsdatum: 19 Apr 2013 11:28
Letzte Änderung: 19 Apr 2013 11:28
PPN:
Sponsoren: The research leading to these results has received funding from the European Community’s 7th Framework Programme under Grant Agreement No. 214864 (SSEEC).
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