Glass formation, crystallization behavior, nanoprecipitate phase, and magnetic properties of Mn-Fe-Si-B-EM (EM = Zr, Nb, V) alloys

In this paper, the as-quenched Mn ₅₅Fe ₁₅Si ₂₀B ₇EM ₃ (EM = Zr, Nb, V) amorphous ribbons were produced by the melt spinning technique. The crystallization behavior, nanoprecipitate phase evolution, and magnetic properties of the Mn-Fe-Si-B-EM (EM = Zr, Nb, V) amorphous alloys were investigated by X-ray diffraction (XRD), differential scanning calorimeter (DSC), and the quantum design dynacool-9 physical property measurement system (PPMS). The Mn ₅₅Fe ₁₅Si ₂₀B ₇EM ₃ (EM = Zr, Nb, V) amorphous alloys show two-stage crystallization behavior. In the first stage, the primary crystallization results in the formation of α-Mn + Mn ₆Si/Mn ₃Si precipitates, while in the second stage, the secondary crystallization leads to the formation of the Mn ₂B phase. The Mn ₅₅Fe ₁₅Si ₂₀B ₇Zr ₃ (FZ) amorphous sample shows a most significant two-stage phase transformation, which the onset temperature of the primary and that of the secondary crystallization are 625.7 °C and 681.2 °C, respectively. The FZ amorphous sample undergoes a magnetic phase transformation from the spin glass (SG) state to a paramagnetic (PM) state at approximately 28 K. As the temperature increases, the magnetic phase transition can be expressed as: SG → PM. The annealed FZ nanocrystalline sample with α-Mn + Mn ₆Si nano phases enters the ferromagnetic (FM) state at 27∼70 K after undergoing spin glass transformation, and the magnetic phase transition is: SG → FM → PM. The annealed Mn ₅₅Fe ₁₅Si ₂₀B ₇V ₃ nanocrystalline sample containing nano α-Mn and Mn ₃Si phases shows two Curie transitions at 57 K and 130 K, respectively. The magnetic phase transition behavior can be expressed as: SG → FMΙ → FMΙΙ → PM.