A metastable Fe₄₈Co₁₀Cr₁₀Mn₃₂ high-entropy alloy with good damping capacity within an ultra-large temperature regime

•We report a metastable Fe48Co10Cr10Mn32 HEA with superior damping capacity (tanδ > 0.01) in a wide temperature range from −100 to 400 ℃ and high strength (σb > 700 MPa) via metastability engineering.•We optimized the damping performance (tanδ ∼ 0.06) through manipulating the FCC-HCP martensitic transformation in the metastable Fe48Co10Cr10Mn32 HEA.•We revealed that the confined martensitic transformation (FCC to HCP) is responsible for the decay of damping capacity of the HEA during cyclic testing.•High entropy effects in the HEA lead to the extended temperature regime of phase transformation and thereby the enlarged working temperature range of superior damping capacity.