Deformation behavior and plastic instability of off-stoichiometric Co–Fe alloys

Deformation-induced grain refinement in body-centered cubic Co–Fe alloys upon room temperature compression

“…1(a and b) shows cross-sectional optical micrographs of the arc-melted Co-Fe alloys. Both alloys exhibit a coarse-grained microstructure with a grain size in the range of 200-500 m. However, Co-35Fe has a slightly finer average grain size than Co-25Fe, similar to what was found in the as-cast specimens by suction casting [17]. The arc-melted samples have about 50-100 m coarser grains than suction-cast rods (Ø15 mm), owing to the lower cooling rate in arc melting (in the order of 1-10 K/s) compared with suction casting (about 100 K/s).…”

“…However, our previous results [17] showed that the as-prepared Co-25Fe alloy by suction casting exhibits a large tensile ductility of ∼20%, equal to that of the disordered alloys after secondary processing treatment [19]. The ductility comes from the formation of predominant wave slip behavior rather than planar slip in conventionally processed Co-Fe alloys [17]. This kind of complex stress and complicated straining pattern will improve ductility by deformation-induced grain refinement forming multiscale grained microstructure, as proved in the occurrence of deformation-assisted grain refinement in arc-melted Co-25Fe alloy during mechanical testing [21].…”

“…by V) and a better understanding of the mechanical behavior of Co-Fe alloys [17][18][19][20]. However, our previous results [17] showed that the as-prepared Co-25Fe alloy by suction casting exhibits a large tensile ductility of ∼20%, equal to that of the disordered alloys after secondary processing treatment [19]. The ductility comes from the formation of predominant wave slip behavior rather than planar slip in conventionally processed Co-Fe alloys [17].…”

“…The Co-25Fe and Co-35Fe alloys (weight percent, the same hereafter) were prepared by arc melting a mixture of the pure elements (99.9 wt%) under a Ti-gettered argon atmosphere [17,21]. The cooling rate was estimated to be in the order of 1-10 K/s.…”

“…Intensive research and development efforts over decades have resulted in a significant improvement of the ductility by microalloying (e.g. by V) and a better understanding of the mechanical behavior of Co-Fe alloys [17][18][19][20]. However, our previous results [17] showed that the as-prepared Co-25Fe alloy by suction casting exhibits a large tensile ductility of ∼20%, equal to that of the disordered alloys after secondary processing treatment [19].…”