Dual magnetic phases in Nd-based bulk metallic glass

Numerous nanocrystals dispersed homogenously in an amorphous matrix were observed in the die-cast cylindrical Nd55Fe28Al9Ni8bulk metallic glass. Most of the nanocrystals are less than 5 nm in size. At room temperature, only one magnetically hard phase was observed. But below room temperature, another magnetically hard phase was also detected. The appearance of the phases was associated with the different exchange coupling effect of the nanocrystalline grains and the amorphous matrix, and the coercivity of the alloy was related to the size of the nanocrystals. It was shown that nanocrytals with a size larger than 1.3 nm might contribute to a larger coercivity of the alloy.