Gradient submicrocrystalline structure in Fe–Cr–Co system hard magnetic alloys

Abstract

The evolution of the structure and microhardness of Fe–25Cr–15Co and Fe–30Cr–8Co (number indicate wt.%) hard magnetic alloys during complex two-stage upsetting-torsion under isothermal conditions at different temperatures is experimentally studied. It is revealed that the deformation leads to a strong refinement of the initial coarse-grained structure in both alloys. The generated structure is non-uniform through the body of the samples and has gradient character. In the active zone of deformation near to the mobile head, there is a microcrystalline layer with a grain size of about 5 μm in a single phase Fe–30Cr–8Co alloy and a micro duplex structure with a grain size of about 0.5 μm in a two-phase Fe–15Co–25Cr alloy. With removal from the active zone of deformation the grain size increases, and microhardness decreases.