Thermodynamic and magnetic properties of multicomponent (Fe,Ni)70Zr10B20 amorphous alloy powders made by mechanical alloying

The correlation between the thermodynamic and magnetic properties of mechanically alloyed (MAed) (Fe1−xNix)70Zr10B20 (x=0.1–0.4) amorphous alloy powders was investigated. The activation energy (Ea) for primary crystallization of the b.c.c. α-Fe phase decreased significantly from 356.7 to 139.7 kJ/mol with increasing Ni/Fe ratio from 0.11 to 0.43 and then increased to 304 kJ/mol for the alloy with a Ni/Fe ratio of 0.67. The Curie temperatures of the (Fe1−xNix)70Zr10B20 (x=0.1–0.4) alloy powders milled at 18 h were found to be in the range 425–625 K. The room temperature coercivity of the as-milled amorphous powders was in the range 37–44 G. However, they were dramatically reduced to values in the range 11–24 G after annealing at temperatures from 250 to 575 K. The minimum coercivities obtained after in situ annealing of amorphous powder were 8 G for (Fe0.6Ni0.4)70Zr10B20 and 10 G for (Fe0.8Ni0.2)70Zr10B20, respectively.