Investigation of nanostructure formation mechanism and magnetic properties in Fe45Co45Ni10 system synthesized by mechanical alloying

Abstract

Mechanism of nanostructure formation and magnetic properties in Fe 45 Co 45 Ni 10 alloy synthesized by high energy milling has been explored in this study. Our results suggested a simultaneous increase in the dislocation density and formation of low-angle grain boundaries when one of the cold welding or fracturing process was predominant (up to 2 h of milling). This was followed by a steady state between cold welding and fracturing (2 to 35 h), which coincided with high angle grain boundaries formation. After milling for 10 h, dissolution of Co and Ni in Fe, correspondingly, resulted in a bcc solid solution. The powders exhibited a minimum grain size of ~ 10 nm and lattice parameter of ~ 0.28512 nm after 35 and 20 h, respectively. Alloy formation enhanced magnetization saturation to about 186 emu/g and grain size refinement decreased coercivity to approximately 32 Oe. Our results suggested a simultaneous increase in the dislocation density and formation of low-angle grain boundaries when one of the cold welding or fracturing process was predominant (up to 2 h of milling). This was followed by a steady state between cold welding and fracturing (2 to 35 h), which coincided with high angle grain boundaries formation. ► We divide nano-structure formation during mechanical alloying into two stages. ► We determine alloying sequence as Co → Ni → Fe. ► Rigorous increase in volume fraction of grain boundaries leads to lattice expansion. ► Alloy completion increases magnetization saturation.