Unveiling the Pressure-Induced Strengthening Mechanism in Mg₁₇Al₁₂: A First-Principles Study on Electronic Structure and Mechanical Properties

Abstract Magnesium alloys hold significant application value in transportation lightweighting, yet the intrinsic strengthening mechanism of their core strengthening phase Mg₁₇Al₁₂ within the high-pressure solidification (HPS) process window remains unclear. Through density functional theory (DFT) multiscale simulations under 4 GPa, this study reveals the electronic-mechanical coupling mechanism of Mg₁₇Al₁₂, demonstrating that hydrostatic pressure induces lattice contraction to 10.29 Å (Δ = -2.3%) and reduces cohesive energy to -162.49 kJ/mol, with phonon spectrum confirming high-pressure stability. Material axial stiffness (C₁₁) and shear modulus (C₄₄) increase by 17% and 16%, respectively, achieving a theoretical strength of 9.41 GPa (46% increase) and a 13.7% enhancement in plastic elongation, thereby realizing a synergistic breakthrough in strength and toughness. Electronic structure analysis identifies s-p orbital hybridization of Al bonds triggering a three-dimensional covalent network, while the coexistence of charge localization at Al sites and free electron gas in Mg-Mg bonds establishes a metal-covalent dual-phase ground state, evidenced by reduced Fermi-level density of states (DOS) and band broadening that reflect dynamic electron localization-delocalization equilibrium. Further electronic reconstruction through covalent network strengthening, brittle index optimization (G/B ratio decrease of 8%), and band discretization defines a cross-scale interaction paradigm of "quantum orbital modulation → mesoscopic bond reorganization → macroscopic property response". These findings provide theoretical guidance for HPS parameter design and high-performance magnesium alloy development, advancing lightweight material design toward electronic engineering principles.