Enhancement of the soft magnetic properties and improvement of the deformation ability of a ferromagnetic (Fe0.76Si0.09B0.1P0.05)99Nb1 bulk metallic glass

• New FeSiBPNbCu BMGs were developed by copper mold casting.
• 0.75at% Cu doping can well improve the local deformation ability.
• 0.75at% Cu doping can well enhance the soft magnetic properties.

Ferromagnetic (Fe0.76Si0.09B0.1P0.05)99−xNb1Cux (x=0, 0.25, 0.5, 0.75, and 1) bulk metallic glasses (BMGs) were synthesized by copper mold casting. The effects of Cu alloying on the glass-forming ability (GFA), microstructure, soft magnetic properties, and local subsurface deformation properties of this alloy series were investigated. The results showed that the addition of an appropriate amount of Cu led to the formation of α-Fe nanocrystals in the as-cast amorphous rods without obvious deterioration of the GFA. The enhancement of the soft magnetic properties of the representative (Fe0.76Si0.09B0.1P0.05)98.25Nb1Cu0.75 alloy was ascribed to α-Fe nanocrystals with a diameter of approximately 3 nm, precipitating and dispersing randomly in the amorphous matrix. In addition, compared with the Cu-free base alloy, the subsurface deformation ability of the as-cast Cu-doped alloys was greatly improved by plastic shear deformation.