G. Korznikova

Microstructure and properties of hard magnetic FeCr30Co8 alloy subjected to plastic deformation by complex loading

Abstract The microstructural, mechanical and magnetic properties of FeCr30Co8 alloy in the a state were examined after upsetting, followed by torsion. The temperatures (750, 800, 850 and 900°C) and deformation rates corresponded to the superplasticity conditions of the Fe–Cr–Co alloys. Due to the torsional deformation, which was applied only to the bottom of the samples, a gradient microstructure was formed in the sections that were parallel to the upsetting direction. In the temperature range from 750 to 850°C, the deformation led to intermetallic r-phase precipitation. The maximum refinement of the microstructure and the maximum r-phase precipitation were observed in the material that was deformed at 800°C. Measurement of the magnetic properties showed a decreasing coercive force in the deformed alloy, in contrast to the mechanical properties of the samples after the magnetic treatment.

Microstructure of Hard Magnetic FeCr22Co15 Alloy Subjected to Tension Combined with Torsion at High Temperatures

The paper presents the results of microstructure evolution studies of hard magnetic FeCr22Co15 alloy, destructed by tension and torsion at 800 and 850°C. The temperatures and deformation rates corresponded to the condition of superplasticity of Fe-Cr-Co alloys. Observations of longitudinal section of deformed samples in scanning electron microscope showed a formation of weak gradient microstructure with highest grain refinement in the surface layer of material. Precipitation of intermetallic σ-phase was also observed, with its maximum amount in zones of the highest deformation.