Mechanical properties and strengthening mechanisms of eutectoid Al₁₀(CoFeNi_1.5)₉₀ multi-component alloy

This work addresses the challenge of achieving eutectoid lamellar microstructures (LMs) in multi-component alloys (MCAs) by investigating the evolution of microstructures and mechanical properties in Al₁₀ (CoFeNi_1.5)₉₀ MCA. The results demonstrate that the FCC phase transforms into LMs when aged between 400 and 600 °C. The mechanical properties depend strongly on the lamellar FCC phase width in the LMs, which, in turn, depends on the aging temperature. Aging at 600 °C yields wide LMs (242 ± 150 nm) with lower strength (YS = 758 ± 18 MPa, UTS = 1219 ± 15 MPa) but higher ductility (UE = 17 ± 3 %), while aging at 450 °C yields thin LMs (45 ± 18 nm) with ultra-high strength (YS = 2091 ± 22 MPa, UTS = 2149 ± 16 MPa) but limited ductility (UE = 1.3 ± 0.2 %). The calculated yield strength of 1180 MPa, obtained from the linear summation method of grain boundaries (σ_GB, 33 %), solid solution (σ_ss, ⁓27 %), dislocations (σ_D, ⁓25 %), and precipitations (σ_P, ⁓15 %) contributions, shows excellent agreement with the experimental value of 1167 MPa.