Ultrastrong and ductile BCC high-entropy alloys with low-density via dislocation regulation and nanoprecipitates

The high strength is a typical advantage of body-centered-cubic high-entropy alloys (BCCHEAs). However, brittleness and weak strain-hardening ability are still their Achilles’ heel. Here, extraordinary strength together with good tensile ductility are achieved in (Zr0.5Ti0.35Nb0.15)100-xAlx alloys (at.%, x = 10 and 20) at room temperature. Relatively low densities of less than 6 g/cm3 are exhibited in these alloys. Designing nanoprecipitates and diversifying dislocation motions are the keys to achieving such salient breakthrough. It is worth noting that the tensile strength of 1.8 GPa in (Zr0.5Ti0.35Nb0.15)80Al20 alloy is a record-high value known in reported BCCHEAs, as well as a tensile strain over 8%. Furthermore, the maximum strain of ∼25% in (Zr0.5Ti0.35Nb0.15)90Al10 alloy can challenge existing limit value, and is accompanied with a tensile strength of 1.2 GPa. The current work does not only provide novel ultra-strong and tough structural materials with low density, but also sheds new light on designing BCCHEAs with attractive performances and strain-hardening ability.