ANNEALING EFFECT ON MAGNETO-ELASTIC WAVE PROPAGATION IN IRON-RICH AMORPHOUS RIBBON

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ANNEALING EFFECT ON MAGNETO-ELASTIC

WAVE PROPAGATION IN IRON-RICH

AMORPHOUS RIBBON

K. Yamada, K. Matsumoto, A. Hasegawa, N. Hiratsuka

To cite this version:

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JOURNAL DE PHYSIQUE

Colloque C8, Suppl6ment au no 12, Tome 49, dkembre 1988

ANNEALING EFFECT ON MAGNETO-ELASTIC WAVE PROPAGATION IN

IRON-RICH AMORPHOUS RIBBON

K. Yamada, K. Matsumoto, A. Hasegawa and N. Hiratsuka

Fac. of Engineering, Saitama University, Urawa, Saitama 338, Japan

Abstract. - The appropriate annealing of the iron-rich amorphous ribbon caused an enhancement of the magneto-elastic wave (MEW) amplitude. But the fluctuation of MEW with the distance along the ribbon became larger by any annealing. The differential magnetization curve sensitively showed a structural relaxation by the annealing.

1. Introduction k 7 10

Magneto-elastic wave (MEW) propagation along w VI

iron-rich amorphous ribbon has been intensively stud- 5 2 2

2

a

ied to utilize it for the electronic devices. For this

₃

₀₉ 21

F

purpose, the uniform propagation along the ribbon

z

is preferable. If the material is homogeneous, MEW r 08

propagates with a constant amplitude under uniform

_-

₁₂

stress and in a magnetic field. However, we found ₀₇

MEW amplitude fluctuation more than 20 % along the 0 2 4 6 8 1 0 1 2

DISTANCE ( cml

ribbon com~osed of F ~ ~ ~ C T ~ B I R S ~ S . . - --

- .

(Allied Chemical

Corp. 20 p i thick). We also found a close correlation Fig. 1.

-

The MEW amplitude, the thickness and the

between the fiuctuations of thickness and the MEW reciprocals of the a.c. magnetization at f = 1 kHz as the

function of the positions along the ribbon direction (MEW amplitude a t each position along the ribbon direction. _frequency₌ _{k ~ ~ ) .}

But the correlation between the fluctuations of MEW amplitude and the reciprocal of the a.c. magnetization (l/m,,) [I] is larger than those between the MEW am-

plitude and thickness. Therefore, it was concluded in AS CAST

the reference 12, 31 as folIows. The geometrical inho-

mogeneity of the roll(s) caused the periodic thickness 4 30.c

deviation with an interval of the roll size. The rapid

quenching speed and, subsequently, the local magneto-

%

a

mechanical constant at each position was varied by the

2

540'~

local deviation of the thickness. Therefore, the MEW 2s fluctuation

each position. was caused by the thickness deviation at

!$Eiil

o DISTANCE 5 10 ( e m ) 15

In this study, we investigated the effects of the an- Fig. 2.

-

The effect of annealing on the MEW amplitudes.

nealing on the MEW propagation to diminish the am- TA in this figure denotes the annealing temperature as ex-

plitude fluctuation. pIained in the text.

2. Experimental results a n d discussions The measurement of the ribbon thickness at each position along the ribbon direction was performed with the accuracy of 0.2 pm for 20 pm thick. More than 20 % deviation from the average thickness was found in an as-cast sample. The MEW amplitude and the a.c. magnetization at f = 1 kHz were also measured for the same sample as shown in figure 1. To study the effects of the annealing on the MEW propagation, the amorphous ribbon was heated up with 40 C/min t o the annealing temperature TA in N:! gas atmosphere. Then i t was annealed a t the constant temperature TA for 30 min, and cooled down with 20 OC/min to R.T. Fig- ure 2 shows the typical annealing effects on the MEW

amplitude variations as a function of the distance along a ribbon for different TA's. In this figure, the MEW amplitudes are normalized by the maximum value at a point and the scale is normalized for each curve. The extent in the amplitude fluctuation curve of the as- cast sample is about 20 %

.

The relative amplitude fluctuations become larger for the curve TA = 430 OC and for the curve of TA = 530 OC than that of the as-cast. It was found that the MEW amplitude fluctuations become larger by any annealing treatment. In

figure 3, the X-ray diffraction intensities from (110), (200) and (211) planes of Fe are shown as the func- tions of different annealing temperatures T A . Figure 4

shows the relative MEW amplitude at a fixed point and the X-ray diffraction intensity from (110) plane

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JOURNAL DE PHYSIQUE

Fig. 3. - The relative MEW amplitude and X-ray diffrac- tion intensity of (110) plane of Fe a s a function of the an- nealing temperature.

01

' / ,

I

400 450 500 550

ANNEALING TEMP. ("C)

Fig, 4. - The X-ray diffraction intensities of (110), (200)

and (211) planes of Fe respectively as a function of the annealing temperature.

wavelength (A = 2 cm at f = 250 KHz). Note here that much shorter range fluctuatio~n of the magneto- mechanical constant than the MEW wavelength does not cause the MEW amplitude fluctuation.

The d.c. magnetization at each annealing stage was also measured in a weak magnetic field range less than

15 Oe. It was found from the M-H curve and the X-ray diffraction pattern that some structural relaxations occured by the annealing of T A

<

430 "C. As-cast sample showed sharp rise M-H curve in the magnetic field less than 3 Oe and gradually increase in the magnetization in the larger field. However the annealed sam- ple a t T A = 430 OC increased in the magnetization withiq H = 0.5 Oe. The X-ray diffraction intensity

of (110) plane of Fe in the sample (TA = 430 OC)

showed three times larger than that in the as-cast. The anriealed sample of T A = 450 OC showed the two peaks in the differential magnetization dM/dH. The first one occured a t less than 0.1 Oe and the second one around at H = 5 Oe. The sample of higher than

TA

>

500 O C showed a large segregation phase of a-Fe

(b.c.c.). At this stage, the M-H curve shows a hard material of H, = 3.9 Oe as twice as that of the soft iron of Hc = 1.8 Oe. The structural

ela ax at ion

thus explained might be caused by the lo~wering of the magnetic anisotropy energy at each position. As the result, the microscopic changes of the amorphous states with increasing TA are monitored by MEW propagation.

as a function of T A . It is obvious from the experimen- [ I ] Shirae, K. e t al.3 AM-76 (1976;) 33.

tal results that the effective magnetic and mechanical [2] Yamada, K. and Mastumoto, K., Proc. Int. constants for the MEW uniform propagation were not Symp. Phys. Magnetic Material, Sedai (1987)

improved by any annealing. Probably, the annealing p. 570.

of the ribbon resulted in the longer range relaxation [3] Yamada, K., Matsumoto, K. and Sugimoto, M.,