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Materialien/Werkstoffe Poster: Do., 13:00–15:30 D-P393
Mössbauer Effect and SANS in F.C.C. FeNiC Alloys after Ultrasonic Impact
Treatment
Volodymyr Nadutov 1 , Vasil Garamus 2 , Regine Willumeit 2 , Denis Semenov 1 ,
Yevgenij Svystunov 1
1 G.V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine, Kyiv, Ukraine
– 2 GKSS Research Centre, Geesthacht, Germany
The ultrasonic surface treatment (UST) is an effective method improving mechanical
properties of metal products and increasing the operation characteristics.
The Invar Fe30.1 %Ni1.18 %C alloy after the UST was studied. The frequency of
ultrasonic vibration of a sample was 1-3 kHz. The phase composition of the alloys was
controlled by X-ray analysis. The transmission Mössbauer spectroscopy and the smallangle
neutron scattering (SANS) were used. The distribution of the hyperfine magnetic
fields was obtained by using the Window method supplemented with procedure of
the determination of the isomer shifts distribution function. The SANS experiments
were performed at the SANS1 instrument at the FRG1 research reactor at GKSS
Research Centre, Geesthacht, Germany. The neutron wavelength was 8.1 ˚A. The range
of scattering vectors (0.005 < q < 0.25 ˚A −1 ) was obtained using four sample-to-detector
distances (0.7 – 9.7 m). The experiments were carried out at room temperature in
applied magnetic field of 2.5 T at a sample perpendicular to the neutron beam, which
was polarized.
From Mössbauer data the UST causes the redistribution of C atoms in the f.c.c. Fe-
Ni-C alloys that results in modification of magnetic order; the UST in the considered
mode does not change the phase composition of the Fe-Ni-C alloys that considerably
differs from the effect of the impact low frequency loading causing the martensitic
transformation.
The SANS experiment did not reveal the effect UST. The SANS curve has shown
two slopes (Fig. 2). The analysis of large q part (q > 0.01 ˚A −1 ) by IFT method gives
Rg = 155 ˚A (the radius of equivalent sphere is 200 ˚A). Dmax = 500 ˚A. The analysis of
lowest q part (q < 0.01 ˚A −1 ) by slope I(q) q ( −α) gives α=4.6 that points existence of
some larger particles with fractal surface of diffuse type.