ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
Several ternary Fe – Ge - C alloys with Ge contents ranging between 3 and 27 at. % havebeen studied. The structure, anelastic, thermodynamic and kinetic phenomena in Fe - 3, - 12, -19/21 and – 27 Ge have been examined by X-ray diffraction (XRD), heat flow (DSC), vibratingsample magnetometry (VSM), optical-light and scanning electron microscopy, and internal friction(IF) methods. The Fe - 3Ge and Fe - 12Ge alloys form b.c.c. solid solutions. A Snoek-type internalfriction (P1) peak is recorded in the Fe - 3Ge alloy with parameters similar to those for α-Fe:Н = 0.86 eV, Δ = 0.015, β = 0.72 and τ0 = 2 × 10-15 s, showing that Ge atoms have little influence onthe diffusivity of carbon in iron. The Fe - 12Ge alloy, with a Curie point around 1008 K, has severalIF peaks: a broad Snoek-type (P1 and P2), the P3 peak caused by structural changes in as quenchedspecimens during annealing, and a P4 (Zener) peak at higher temperature (Tm ≈ 773 K at f = 2 Hz,β ≈ 0.7). The Fe - 21Ge alloy has bcc or bcc plus hexagonal structure depending on heat treatment.The structure of the Fe3Ge-type alloy (Fe - 27Ge) consists mainly of hexagonal phases, i.e. hexagonalε (D019), β (B81), and cubic ε′ (L12), and exhibits corresponding magnetic ordering transitionsbelow 873 K which are not well-reflected in the common Fe - Ge phase diagrams. In particular ahigh stability of the hexagonal ε phase at room temperature is noted. A broad internal friction relaxationpeak with Δ = 0.0036, H ≈ 1.8 eV and τ0 = 2 ⋅ 10-17 s is found in Fe – 27 Ge and is classifiedas a double Zener peak in the ε and β two-phase mixture
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.137.59.pdf
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