Effect of Nb, Si and Cu on the crystallization process and magnetic properties of FeNbBP alloys

Abstract

The effect of Nb, Si and Cu on crystallization process and magnetic properties of the Fe84Nb1B5P9M1 (M = Nb, Si, Cu) alloys were investigated. The experimental results show that the substitution of P by Nb, Si, or Cu leads to a wider interval between two crystallization exothermic peaks in comparison to that of the Fe84Nb1B5P10 alloy. The addition of Cu decreases the primary crystallization temperature (Tx1) of alloys while the doping with Si increases the Tx1 slightly. It is clear that the secondary crystallization temperature (Tx2) increases with the substitution of P by Nb, Si and Cu. Among the three elements, Nb has the largest effect on the precipitation of Fe(B,P) phases, which is due to the large negative mixing enthalpy of Nb and B, P. Based on the measurement of apparent activation energy, it is found that the shift in secondary crystallization peak to higher temperature is mainly due to the decrease in P content. After optimum annealing treatment, the Fe84Nb1B5P9M1 alloys show magnetic flux density above 1.7 T and coercivity below 10 A/m, which is better than Fe84Nb1B5P10 alloy.