Tailored rapid annealing to obtain heterostructured ultra-high-strength lightweight Ti-rich medium-entropy alloys

Thermomechanical treatment (TMT) is a widely used process for effectively enhancing the mechanical properties of conventional metallic materials. This study applied TMT along with rapid annealing to a lightweight (≈5 g/cm3) Ti-rich Ti65(AlCrNb)35 medium-entropy alloy (Ti-65 MEA) to equip it with a heterogeneous structure (heterostructure). After the annealing treatment, the Ti-65 MEA exhibited a heterogenous microstructure comprising nonrecrystallized shear bands and ultrafine recrystallized grains. Remarkably, the heterostructured Ti-65 MEA had extraordinary mechanical properties (tensile strength, 1500 MPa; elongation, 25%) and ultrahigh specific strength (247 MPa cm3/g).