The effect of Copper alloying additions on the crystallization of an amorphous Fe–Si–B alloy

The effect of Cu alloying additions on the crystallization of Fe–Si–B alloy was studied. The selected alloys compositions are Fe_77.5Si_13.5B₉ and Fe_76.5Si_13.5B₉Cu₁. By comparing their crystallization temperatures, activation energy of crystallization, phase formation and microstructural evolution after heat treatment, the effect of Cu alloying additions was determined. It was found that Cu alloying additions reduced the crystallization temperature as well as the activation energy of the crystallization. Although the phases formed in both alloys were Fe₃Si and Fe₃B phases the microstructures were dramatically different: a dendritic microstructure was observed in the case of the Fe–Si–B alloy, while spheriodal crystals around 100 nm in size were observed in the case of the Fe–Si–B–Cu alloy. Cu alloying addition increased the saturation magnetization during primary crystallization whereas it decreased the saturation magnetization after secondary crystallization began. Interestingly, for both alloys the same trends of the magnetization and coercivity measurements were observed except that the extent of the changes were higher in the case of the Fe–Si–B–Cu alloy than that of the Fe–Si–B alloy.