Concurrent strength and conductivity enhancement in a dilute Al-Ce alloy: grain refinement, Fe/Si redistribution, and...

While rare-earth Ce additions can improve both the electrical conductivity and mechanical strength of commercial-purity Al, the origins of this simultaneous enhancement remain difficult to separate. Here, multi-scale characterization (OM, SEM/EDS, XRD, and HRTEM/HAADF) was combined with first-principles calculations to examine the effects of 0.07 wt% Ce in 1085Al. Ce addition increased the mean electrical conductivity from 58.86 ± 2.05 to 63.62 ± 0.78 %IACS. The mean ultimate tensile strength increased from 44.86 ± 2.36 to 61.87 ± 3.82 MPa, while the mean elongation increased from 29.43 ± 2.11% to 35.43 ± 0.35%. The mean grain size decreased from 126.8 ± 10.9 to 78.5 ± 14.2 µm. SEM/EDS showed Fe and Si enrichment in micrometre-scale spheroidal Al-Fe-Si-Ce particles, while local HRTEM fringes and FFT features were consistent with an Al₁₁Ce₃-type lamellar constituent within these particles. The resistivity calculated from the mean conductivity decreased from approximately 29.29 to 27.10 nΩ m (Δρ ≈ -2.19 nΩ m). A semi-quantitative Matthiessen-rule analysis associated this change mainly with reduced matrix-solute scattering after Fe/Si redistribution. The local orientation suggested by HRTEM was represented by a (200)_Al//(060)_Al11Ce3 interface model with nominal in-plane mismatches of 8.27% and 6.11%. PDOS and COHP analyses showed localized Al-p/Ce-d hybridization and greater stabilization of the selected L1 Al-Ce contact than of L2, with ICOHP values of -1.027 and -0.690 eV per bond, respectively. These bond-specific descriptors characterize relative stability but do not quantify interface resistance or an electron-scattering cross-section. The results link Fe/Si redistribution and localized interface bonding to the concurrent changes in conductivity and mechanical properties while retaining the limits of the available measurements.