Mössbauer-effect study of iron-boron-beryllium metallic glasses

${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ Mössbauer spectra have been obtained at both liquid-nitrogen and room temperatures for a series of metallic glasses ${\mathrm{Fe}}_{82}{\mathrm{B}}_{18-x}{\mathrm{Be}}_x$ with $0<~x<~6$. With the use of Window's program the spectra were fitted and deconvoluted to obtain the probability distribution function of the effective magnetic hyperfine field $P\left(H\right)\mathrm{}$, and the results show a well-defined symmetric shape for these metallic glasses. The width of $P\left(H\right)\mathrm{}$, $\Delta H$, remains approximately constant at a value of 80 kOe for all samples. However, the most probable value of the effective magnetic hyperfine field $H_1$ at liquid-nitrogen temperature initially increases with the Be content to 4 at.%, but starts to decrease as $x$ exceeds 4. The isomer shift has a value of -0.032 mm/sec for samples with $x<~4$ but changes to -0.050 mm/sec for samples with $x>\mathrm{}4\mathrm{}$. The crystallization products obtained upon annealing the ${\mathrm{Fe}}_{82}$ ${\mathrm{B}}_{18}$ metallic glass at $T_a=420\mathrm{}$°C were identified as tetragonal ${\mathrm{Fe}}_3$B and $\alpha$-Fe. The annealing of the samples with $x>\mathrm{}0\mathrm{}$ between $T_{x1\mathrm{}}$ and $T_{x2\mathrm{}}$ yields a metastable amorphous phase and crystalline solid solutions of an Fe-Be phase. Annealing of the samples with $x>\mathrm{}0\mathrm{}$ above $T_{x2\mathrm{}}$ yields crystalline Fe-Be solid solutions and the ${\mathrm{Fe}}_2$B intermetallic compound. The intensity ratios in the Mössbauer spectra clearly indicate that annealing of samples between $T_{x1\mathrm{}}$ and $T_{x2\mathrm{}}$ led to the alignment of the ${\overline{H}}_{\mathrm{eff}}$ direction close to the ribbon plane, but annealing above $T_{x2\mathrm{}}$ left ${\overline{H}}_{\mathrm{eff}}$ randomly oriented.