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

Deformation responses of two as-cast off-stoichiometric Co–Fe alloys have been investigated under compression and tension. Both alloys exhibit large plasticity (≳100%) without softening or fracture under compression. Under tension, the Co–25Fe alloy shows a large ductility of ∼20% similar to that reported for other hot-extruded alloys displaying a clear necking morphology, whereas Co–35Fe fails in a brittle manner by mixed intergranular and transgranular fracture. The ductility in tension is sensitive to the capacity for strain hardening under compression.