The way to improve strength and ductility of heavily carbon-alloyed high-entropy Fe20Mn20Cr20Ni20Co15C5 alloy

In this work we propose a new approach to improve strength and ductility of the heavily carbon-alloyed high entropy Fe20Mn20Cr20Ni20Co15C5 alloy, which is characterized by extremely low plasticity in cast state (δ = 5%, σUTS = 633 MPa). Novel thermal treatment regime, combining 5-h homogenization at T = 1200 °C with intermediate thermal cycling down to the room temperature, provides the 4-times increase in ductility and high values of strength characteristics (δ = 19%, σUTS = 905 MPa) due to the partial dissolution and smoothing of the carbides. Such complex processing regime provides better strength/ductility combination than those for the individual effects of a solid-solution treatment (dissolution of precipitates and solid-solution hardening of the austenite) or a thermal cycling treatment (refinement of carbide inclusions). •Cast Fe20Mn20Cr20Ni20Co15C5 alloy contains coarse carbides in austenitic matrix.•Plasticity of the cast heavily C-alloyed Cantor alloy is extremely low.•New treatment combines solution treatment and multistep heating/cooling cycling.•Novel thermal treatment provides 4-times increase in elongation of the alloy.