Annealing induced enhanced magnetic properties of Co35Cr5Fe10Ni30Al20 high entropy alloy: Insights from photoemission spectroscopy and x-ray magnetic circular dichroism

Abstract

High entropy alloys (HEAs) are expected to overcome the shortcomings of conventional alloys owing to their vast compositional space and unique multifunctional properties. Designing and developing novel HEAs with high saturation magnetization (Ms) is challenging, which prevents these alloys from replacing conventional soft magnetic materials. We synthesized Co35Cr5Fe10Ni30Al20 HEAs through mechanical alloying, possessed a major fcc phase with minor bcc phase, and the value of Ms is found to be 51 emu/g. The as-synthesized HEA, annealed at 700 °C for 2 h, possessed bcc as a primary phase and fcc as a minor phase. A significant increase in the value of Ms was observed from 51 to 110 emu/g for the annealed Co35Cr5Fe10Ni30Al20 HEA. This enhancement in Ms is explored through the advanced synchrotron-based characterizations. The synthesized and annealed sample was characterized for element-specific magnetization through x-ray magnetic circular dichroism (XMCD), and it was found that after annealing, the magnetic moment corresponding to Fe, Co, and Ni was enhanced significantly. Moreover, the electronic structure after annealing is also investigated through angle-integrated photoemission spectroscopy and found that the density of the state near the Fermi level changes significantly. This study provides detailed insights into the change in the value of Ms after annealing through photoemission spectroscopy and XMCD measurements. Moreover, the results of the study will be helpful for the development of novel HEAs for industrial applications.