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Submitted on 1 Jan 1988
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HEAT TREATMENT INFLUENCE ON THE
ELASTICITY MODULI OF THE Fe79Si12B9
METALLIC GLASSES
Z. Kaczkowski
To cite this version:
JOURNAL DE PHYSIQUE
Colloque C8, SupplBment au no 12, Tome 49, d6cembre 1988
HEAT TREATMENT INFLUENCE ON THE ELASTICITY MODULI OF
THEFe7gSi12Bg METALLIC GLASSES
Z. KaczkowskiPolish Academy of Sciences Institute of Physics, Al. Lotniko'w 32/46, PL-02-668 Warszawa, Poland
Abstract. - The influence of the heat treatment and the magnetic bias field on the moduli of elasticity of the Fe7gSi12Bg
metallic glasses were investigated. The annealing temperature were changed from 250 to 350 OC. The observed A E effect is connected with the magnetomechanical coupling, which increases with the rise of the annealing temperature up to the range of the Curie temperature.
1. Introduction
The elasticity moduli and magnetomechanical cou- pling coefficient dependences on the magnetic bias field for the as quenched Fe79Si12Bg metallic glasses were presented in the previous author's paper [I]. Now the influence of the annealing at the temperatures of 250, 300 and 350
'C
for 0.5 hour on these parameters is discussed.2. Experiment and results
The measurements were carried out on the as quenched and annealed Fe7gSilzBg metallic glass al- loy obtained by single roll quenching technique. The strip shape samples were cut out from the 10 mm wide ribbons with the thickness changing from 20 to
35 pm.. The length of the 4 mm wide strip was equal to 50 mm. Density p of the samples was equal t o 7.2 ~ ~ /Their saturation induction for as quenched m ~ . state was equal to 1.38 T and the saturation magne- tostriction reaches 34 x The motional impedance circles were obtained using the phase-sensitive volt- meters. The moduli of the elasticity a t the constant magnetic field EH and at the constant magnetic induc-
tion EB have been determined from the density and the resonant f r and antiresonant f, frequencies of the half wave resonators, i.e. investigated strips with the length I = X
/
2, e.g. [I, 21.The dependences of the
EH
and EB moduli on themagnetic bias field after the different heat treatment for the amplitude of the alternating field equal to
3 A/m and frequency ranging from 42 to 46 kHz are presented in figure 1. Generally, the moduli of the elas- ticity in the complex form have the real and imaginary terms. The ratio of the imaginary part of the elasticity modulus to its real part is defined as the mechanical quality factor Q and its reciprocal as the internal fric- tion coefficient Q-
,
e.g.The internal magnetomechanical friction coefficient
was determined from the quadrantal frequencies fi and f2 and resonant frequency f r
*-I
-
f 2-
fl
H---
f*
(2)The characteristics of the internal friction coefficient versus magnetic field are presented in figure 2. Ffom the differences between the
EB
and EH moduli the magnetomechanical coupling coefficient k , one of the most important parameters of the piezomagnetic ma- terials, e.g. [2], can be calculated (Fig. 3). The depen- dences of the moduli of elasticity and k coefficient on the annealing temperature are presented in figure 4.Fig. 1. - Moduli of elasticity EH and EB us. magnetic bias field H for the same as quenched and annealed strip.
Fig. 2. - Internal friction Q-' vs. magnetic bias field H.
C8 - 1350 JOURNAL DE PHYSIQUE
Fig. 3. - Magnetomechanical coupling coefficient Ic vs.
magnetic field for the same Fe79SilzB9 sample after differ- ent heat treatment.
Fig. 4.
-
Moduli Eo, EH ,,; and E, and magnetomechan- ical coupling coefficient ,,k and at the bias of 100 and 500 A/m vs. the annealing temperature T.3. Discussion and conclusions
ence on the decreasing the internal stresses connected with the metallic glass producticbn and the maxima of the k coefficient for the as queioched and annealed at the temperatures of 250 and 300 OC were equal to 0.4 f 5 %. The moduli of the elasticity change from 120 to 180 GPa and increase at the saturation after annealing for 112 h at 350 OC. At the saturation when the all magnetization vectors are p;wallel and magnetic domain structure vanishes the mocluli are the real ma- terial constants and the Hooke's law is valid. The quality factor of this alloy changed from 50 to 800. This material exhibits good properties for the appli- cations in the ultrasonic technique as the cores of the piezomagnetic transducers because magnetomechani- .cal coupling coefficient is higher than 0.4, Q may be higher than 100, then saturation induction is two times higher than that of the classical p:iezomagnetic nickel and their resistivity (pel = 1.2 ~OJIL) is 18 times higher than that of the Ni. Annealing in the magnetic field improves signicantly piezomagnetic properties of the metallic glasses, e.g. [3-51.
Acknowledgment
This work was supported by Warsaw Technical Uni- versity Institute of Material Science and Engineering in the frame of the CPBR 2.4.
[I] Kaczkowski, Z., Magnetic Properties of Amor- phous Metals, Eds. A. Hernitndo, V. Madurga, In the region of the bias fields at which the minima M. C. Sanchez-Trujillo, M. Vazquez (Elsevier ~ c i . of the elasticity moduli at the constant magnetic field Publ. BV., Amsterdam) 1987, pp. 136-138.
EH
occurred (Fig. 1) the local maxima of the inter- 121 Kaczkowski1 Z.1 Arch. Acoust- 6 (1981) 385-400. nal friction (Fig. 2) and magnetomechanical coupling 131 Brouha, M.9 van der Borst, J.9 J. Apple Phys. 5 0 (Fig. 3) were observed. Annealing near the Curie tem- (1979) 7594-7596.perature (T, w 410 O C ) increases the magnetomechan- [4] Mitchell, M. A., Cullen, J. R., Abbundi, R.,
ical coupling. Increasing of k up t o 0.52 was observed Clark, A., Savage, H., J. Appi. phis. 5 0 (1979) after the sequence of the annealing for 112 hour at 1627-1629.
