Crystallization of Co_58-xMn₂₀Ge_xB₁₀Si₁₂ (x = 5, 10) metallic glasses

Germanium was introduced at different fractions (5 and 10 at.%) into the Co₅₈Mn₂₀B₁₀Si₁₂ (numbers indicate at.%) alloy to study its effect on the crystallization behavior of the amorphous alloy. It was shown that the Ge addition delayed the onset of devitrification by ∼20 °C, forcing the primary crystallization to nearly coincide with the subsequent eutectic reaction. Metastable SiB₆ was observed to co-nucleate with Co₂Mn(SiGe) due to the Si rejection from Co₂Mn(SiGe) when annealed at 550 °C for both alloys. In addition, Co₄₈Mn₂₀Ge₁₀B₁₀Si₁₂ exhibited a pronounced structural relaxation behavior which was absent in the Ge-free Co-Mn alloys. Estimation of the activation energies showed that increasing Ge addition forced the crystallization kinetics progressively sluggish. We demonstrated that the Ge addition to the Co-Mn amorphous alloy had substantial effects both on the crystallization path and on the kinetics, which well correlated to the ensuing magnetic properties of the thermally annealed Co-Mn-Ge amorphous alloys.