Depth-Selective Study of Surface Crystallization in NANOPERM-Type Alloys

Evolution of structure and magnetic order is studied in the $\text{}^{57}Fe_{81}Mo_{8}Cu_{1}B_{10}$ alloy by conversion electron and conversion X-ray $\text{}^{57}Fe$ Mössbauer spectrometry. Surface features exhibit differences at both sides of ribbon-shaped samples with respect to the screening depth. In the as-quenched state, traces of magnetite (in addition to bcc-Fe) are revealed only at the wheel side of the ribbon to the depth of about 200 nm. It is present also after annealing up to 510 °C, then it disappears. In deeper regions (down to 1 μm), magnetite is less abundant. At the air side, only bcc-Fe is detected, though the progress of crystallization is more pronounced here than at the wheel side. Vibration properties of the bulk of amorphous and nanocrystalline samples are obtained from experiments of nuclear inelastic scattering of synchrotron radiation using partial densities of phonon states.