Microstructural evolution and magnetic properties of Co-rich Hf-Co alloys

Hf - Co binary alloys with different Hafnium concentration ranging from 12.5 to 20.5 at% have been prepared and characterized for structural attributes and magnetic properties. The alloy with 12.5 at% Hf exhibits a large volume fraction of soft magnetic α-Co(Hf), which impairs the hard magnetic properties. With increase of Hf concentration, the volume fraction of soft magnetic phase decreases with increase in fraction of HfCo7, leading to improvement of hard magnetic properties. The HfCo7 phase is found to be responsible for permanent magnetic behavior of the Co-rich Hf-Co binary alloys. The microstructural evolution has been unraveled through the understanding of solidification sequence and correlated with observed magnetic properties.