Non-isothermal crystallization kinetics of Fe₇₅Cr₅P₉B₄C₇ metallic glass with a combination of desired merits

The non-isothermal crystallization kinetics of our previously reported Fe₇₅Cr₅P₉B₄C₇ metallic glass (MG) was systematically evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). The primary crystalline phases of the present alloy annealed under non-isothermal heating conditions were mainly identified as nanocrystalline α-(Fe,Cr), (Fe,Cr)₃P, (Fe,Cr)₃C and (Fe,Cr)₂₃(C,B)₆ embedded in amorphous matrix by XRD and TEM. The apparent activation energy (E) for characteristic temperatures determined by Kissinger method is similar to that determined by Ozawa method. The E_g for the glass transition temperature is larger than both of the E_x for the onset crystallization temperature and the E_p for the peak temperature, indicating that the energy barrier for the glass transition is higher than that for the crystallization. Furthermore, the local activation energy evaluated by Kissinger-Akahira-Sunose (KAS) method and Ozawa-Flynn-Wall (OFW) method shows similar trend of gradual increase with the progressing of the crystallization process, implying that the improved difficulty of crystallization. Additionally, the local Avrami exponents gradually decreased from the values larger than 2.5 to the values smaller than 2.5, which implies a typical diffusion-controlled growth with variable crystallization mechanisms during the whole process.