Amorphization and evolution of magnetic properties during mechanical alloying of Co_(62)Nb_6Zr_2B_(30): Dependence on starting boron microstructure

摘要

Co_(62)Nb_6Zr_2B_(30) composition was mechanically alloyed using three different types of boron powders in the starting mixture: crystalline p-B, commercial amorphous B and optimized amorphous B via ball milling. Using optimized amorphous B, amorphization process of the alloy is more efficient but milling to opti mize amorphous B introduces some iron contamination. Boron inclusions (100-150 nm in size) remain even after long milling times. However, using amorphous boron reduces the fraction of boron distributed as inclusions to ～40% of the total B. Thermal stability at the end of the milling process is affected by the initial boron microstructure. Coercivity is reduced a half using amorphous B instead of crystalline B in the starting mixture.