Evolution of the texture, microstructure, and magnetic properties of a Permimphy alloy after accumulative roll bonding and aging

Soft magnetic materials (SMMs) are extensively used in various fields such as power generation, energy transfer and electromagnetic interference damping. The preparation of SMMs in different forms requires expertise in diverse fabrication techniques. Furthermore, achieving optimal performance requires an understanding of the relationship between magnetic behavior and microstructure and mechanical properties of SMMs. This study focuses on analyzing the effects of accumulative roll-bonding (ARB) processing on the texture, microstructure, and magnetic properties of a commercial Permimphy alloy (Fe-80Ni-5Mo wt%). Electron BackScattered Diffraction (EBSD) analysis confirmed the expected refinement of the grain structure resulting from ARB processing, leading to a reduction in the transverse dimension of the elongated grain down to 800 nm after five cycles. The microhardness of the alloy increased by 80% compared to the as-received sample, primarily due to the refinement of the microstructure and the formation of a high density of dislocations. The findings suggest that the magnetic domain walls are more affected by low-angle boundaries rather than grain/high-angle boundaries. In addition, it was proved that subsequent annealing at 550 degrees C for one hour improved the alloy's magnetic softness while maintaining the mechanical hardness achieved through ARB deformation. This improvement was attributed mainly to the removal of stresses and defects in the material without initiating the process of recrystallization.