Structural and low-temperature magnetic properties of as-quenched and annealed Ni–Si–B alloys produced by rapid solidification

Structural characterization (differential scanning calorimetry, DSC, and X-ray diffraction, XRD) and temperature dependence of the magnetization are reported in Ni₈₀Si₁₀B₁₀ and Ni₇₅Si₁₅B₁₀ alloy ribbons produced by rapid solidification. XDR and DSC measurements lead to confirm the amorphous character of Ni₇₅Si₁₅B₁₀ alloy while the Ni₈₀Si₁₀B₁₀ alloy presents a mixture of amorphous and crystalline (Nickel face-centered cubic) phase. Low-temperature magnetization dependencies were analyzed in terms of spin-wave excitation and fluctuations of the exchange interaction. While both mechanisms are relevant for the high Ni-content alloy, fluctuations of exchange could be ascribed as mechanism for low Ni-content alloy. The effect of annealing (523 and 623 K during 1 h) on the magnetic behavior is also presented. Thus, annealing of Ni75 sample at 623 K also results in appearance of highly magnetic Ni phase.