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Title: Temperature dependence of mechanical properties of the Fe81Ga19 (Galfenol) alloy
Authors: L. W. Pai
S. U. Jen
Y. Y. Lo
Contributors: 國立臺灣海洋大學:光電科學研究所
Keywords: high temperature mechanical properties
galfenol alloy
magnetic damping capacity
magnetic and non-magnetic ∆E effects
Date: 2016-03
Issue Date: 2018-07-04T03:04:24Z
Publisher: Journal of Physics D: Appl. Phys.
Abstract: Abstract: Mechanical properties of most metals or alloys are anelastic (i.e. not ideally Hookeian).
The Fe81Ga19 (Galfenol) alloy is no exception. Mechanical properties, such as the Young’s
modulus (E) and damping capacity (∆W/W), were measured by the impulse excitation method
under the following two conditions [1]: temperature (T) varied from room temperature (RT)
to 300 °C, and [2] external magnetic field (H) changed from 0 to 200 Oe. In the E versus
T plot (when H = 0), there is a downward kink at T = TmF = 232 °C, which indicates that
when T < TmF, we have the un-relaxed Young’s modulus (EU), and when T > TmF, the
relaxed Young’s modulus (ER). The anelastic (or non-magnetic) ∆E effect (near TmF) is
defined as (∆E)A = [EU − ER]/ER = 0.46% (a downward shift from EU to ER). In turn, in
the E versus T plot (when H = 200 Oe), there is almost no kink at TmF, which implies an
off-set due to the magnetic ∆E effect: (∆E)H = [EH − ER]/ER = 2.67% (an upward shift
from ER to EH), when T ≅ TmF. The quality factor (1/Q) ≣ ([1/2][∆W/W]) at constant flexure
resonance frequency can be plotted as a function 1/T. From this plot, we conclude that (i) the
experimental magnetic (or micro-eddy-current) damping capacity (mDC), due the magnetic
domain wall (MDW) motion contribution, at Debye peak (i.e. when T = TmF) is [∆W/W]eExp
≣ [∆W/W]H=200 − [∆W/W]H=0 = 1.7%, while the theoretical mDC for the alloy is found to
be [∆W/W]eTh = 1.2%; (ii) the activation energy, when H = 200 Oe, is EA = 0.81 eV atom−1
(the Snoek type), and the activation energy, when H = 0, is EA = 1.03 eV atom−1
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/47172
Appears in Collections:[光電科學研究所] 期刊論文

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