Cooling Rate‐Mediated Microstructural Engineering in Al–Si–Mg Alloy Conductors: Toward Balanced Optimization of Strength, Ductility, and Electrical Conductivity

The size distribution, number density, and spatial uniformity of strengthening precipitates were precisely tailored for low‐alloyed Al–Si–Mg based alloy wires by systematically modulating the cooling rate after solution treatment. Increasing cooling rate drives progressive precipitate refinement in hard‐tempered Al–Si–Mg wires: furnace‐cooled (FC) samples exhibit predominantly elongated, strip‐like precipitates; air‐cooled (AC) samples contain equiaxed submicron particles with narrow size dispersion; and water‐cooled (WC) samples show near‐suppression of equilibrium precipitation, retaining only sparse, nanoscale solute clusters. The fine, uniformly distributed precipitates in the AC samples exhibit elevated flow stress during cold deformation—attributable to enhanced dislocation pinning. Coarse precipitates in FC samples effectively suppress abnormal grain growth during annealing via robust Zener pinning, improving microstructural homogeneity and enhancing ductility by mitigating localized stress concentration. Nanoscale precipitates in WC samples deliver potent dislocation strengthening while imposing minimal electron scattering. Quantitative modeling confirms that strategically shifting the dominant strengthening mechanism from grain boundary‐mediated to dislocation‐ and precipitate‐dominated pathways yields a 32.5 MPa in ultimate tensile strength (UTS) with only a 0.18% IACS reduction in EC. Ultimately, the AC condition demonstrates a favorable balance among strength, ductility, and EC in Al–Si–Mg alloy conductors, attributed to optimized grain structure, solute distribution, and precipitation behavior.