Spin-echo NMR study of the atomic site environments in the Fe ₆₇Co₁₈B₁₄Si₁ metallic glass

In order to investigate the near neighbor atomic environment and, consequently, the relationship of such environments to the observed magnetoelastic properties, a spin-echo NMR study of the hyperfine field distributions in Metglas 2605 CO (Fe₆₇Co₁₈B ₁₄Si₁) for various magnetic annealing treatments has been undertaken. Here, initial spectra for the ¹¹B metalloid and ⁵⁹Co transition metal nuclei, obtained at 4.2°K and zero magnetic field, are presented along with supplementary magnetization and x-ray diffraction measurements. Upon annealing, a bcc α-Fe phase precipitates first, leaving a residual amorphous phase of lower Fe content. The appearance of such crystalline regions is accompanied by a strong reduction in the magnetomechanical coupling coefficient.