Investigation Of Combustion Mechanism And Soft Magnetic Property Of Fe-based Amorphous Alloys With An Anomalous Exothermic Phenomenon

In this paper,we systematically investigated the combustion mechanism and soft magnetic properties of Fe-Nb-B-Y and Fe-Nb-B-Dy amorphous alloys with an anomalous exothermic phenomenon.Firstly,Fe-based amorphous ribbons'combustion mechanism with an anomalous exothermic phenomenon was systematically studied by using in-situ synchrotron X-ray diffraction,differential scanning calorimetry,thermogravimetric analysis,and X-ray photoelectron spectroscopy.Compared with Fe-Nb-B-Y amorphous alloys with normal thermophysical behaviors,(Fe_0.72B_0.24Nb_0.04)_95.5Y_4.5 amorphous ribbons with an anomalous exothermic phenomenon possess low ignition temperature and self-propagating combustion behavior due to the catalysis of the rapid crystallization exothermic process.The anomalous exothermic phenomenon and its associated liquid-liquid phase transition may induce rapid crystallization and the following multi-step oxidation at the high temperature during heating.Meanwhile,the high-temperature oxidation's activation energy could be significantly reduced,and the energy barrier of the oxidation reaction could be lowered due to the liquid-liquid phase transition.In this way,the oxidation reaction at high temperatures could be promoted.The results suggest that the liquid-liquid phase transition has an"induced activation"effect on Fe-based amorphous alloys'combustion.Also,Fe-based amorphous alloys'soft magnetic properties with an anomalous exothermic phenomenon were systematically studied using the physical property measurement system in this work.The results show that(Fe_0.72B_0.24Nb_0.04)_95.5Y_4.5amorphous alloys with an anomalous exothermic phenomenon possess the excellent glass-forming ability and soft magnetic properties.The coercivity is 22A m^-1;the saturation magnetization is 142A m² kg^-1,and the Curie temperature is 481K.To further verify the above rules,the combustion behavior and soft magnetic properties of Fe-Nb-B-Dy amorphous alloys were systematically studied by the same means.The results suggest that(Fe_0.71Dy_0.05B_0.24)₉₆Nb₄ amorphous alloys with an anomalous exothermic phenomenon can also conduct self-propagating combustion and possess better soft magnetic properties than(Fe_0.72B_0.24Nb_0.04)_95.5Y_4.5amorphous alloys.The coercivity is 1.78A m^-1,and the saturation magnetization is 143A m² kg^-1.The Curie temperature is found to be 524K.Simultaneously,a new Fe-based amorphous alloy with outstanding self-propagating combustion behavior,Fe₆₆(Y_0.25Ho_0.25Er_0.25Tm_0.25)₅Nb₆B₂₃was also invented in this paper.To sum up,our study revealed the correlations among the anomalous exothermic phenomenon,combustion behavior,and soft magnetic properties.Fe-based amorphous alloys'combustion mechanism with an anomalous exothermic phenomenon was also explored using in-situ synchrotron X-ray diffraction.Our results should be a useful reference for environmental-friendly energetic materials with low cost,low ignition temperature,and high combustion heat.Furthermore,our work may shed light on the research and development of functional materials with excellent combustion behavior and magnetic properties.