Phase-field simulation study on the mechanical behavior and fracture mechanism of SiC-p/Al composites considering microstructural effects under uniaxial tension

Abstract

A microstructure-based fracture phase-field model was employed to reveal deformation and failure mechanisms in SiC particle-reinforced aluminum (SiC-p/Al) composites under tension. By integrating real microstructure reconstruction with elastoplastic fracture phase-field theory, the model captures stress distribution, crack initiation, and propagation dynamics across varying SiC volume fractions (10 %, 15 %, 20 %). Key findings demonstrate that lower SiC content induces localized stress concentrations near particle polar regions, while higher fractions form interconnected high-stress networks (>800 MPa) due to reduced interparticle spacing and stress bridging effects. Equivalent plastic strain transitions from localized shear bands to diffuse distributions as particle interactions intensify, though cluster-induced strain hotspots (>0.03) persist at 20 % SiC. The simulations reveal three distinct failure modes: (1) low-volume composites exhibit tortuous crack paths with delayed coalescence, driven by matrix plasticity; (2) intermediate fractions show accelerated crack linkage along interparticle channels; (3) high-volume clusters trigger brittle-dominated failure mechanisms involving interfacial debonding and particle cleavage. A peak strength-ductility synergy occurs at 10 % SiC, while 20 % SiC shows severe embrittlement with rapid crack network percolation. Simulations capture adaptive "circum-particle/matrix-penetrating" crack alternation and cluster-induced secondary cracking leading to macroscopic fracture bands. This multiscale approach bridges microstructural realism with fracture predictability, emphasizing interfacial strength and dispersion uniformity as critical damage tolerance factors for designing high-performance composites.