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[Display omitted] • Compressive strength and internal fracture of Al-Mg 2 Si composites. • Actual microstructure-based RVE models. • Micromechanics and compressive failure of Al-Mg 2 Si composites. • Energy dissipation of Al-Mg 2 Si composites subjected to compression. Al-Mg 2 Si composites have been developed through gravity die-casting techniques. The influence of Mg 2 Si reinforcement concentration on strength, micromechanics and failure initiation of Al-Mg 2 Si composites subjected to compression has been studied. The compressive strength and brittle fracture of the Al-Mg 2 Si composite increase and strain decrease with an increase in Mg 2 Si concentration. The eutectic and primary Mg 2 Si phase sharp corners and narrow sections of Mg 2 Si are fracture initiation sites, and the Al phase nearby the eutectic and Mg 2 Si phase sharp corners and narrow Al phase regions between two Mg 2 Si islands are void initiation sites in the composites subjected to compression. [ABSTRACT FROM AUTHOR]

In-situ Al–Mg 2 Si composites (0, 5, 10, 15, 20 wt% Mg 2 Si) were synthesized in an Al–Mg–Si system through gravity casting route. Influences of the Mg 2 Si addition (in terms of Mg and Si) on the mechanical properties, microstructural morphology, fracture behaviors, micro-mechanical response and failure initiation were systematically studied through experiments and mathematical modeling. Experimental results show that the primary Mg 2 Si formed in Al-10 wt% Mg 2 Si composite and the volume percentage and size of primary Mg 2 Si particles are increasing with an increase in Mg 2 Si concentration in the composite. The Mg 2 Si reinforcement significantly improves ultimate tensile strength (UTS), hardness and yield strength (YS) of the composite, but unwantedly the elongation decreased. Fracture surface analysis reveals that the composites have both the ductile and brittle mode of fracture and the amount of brittle fracture increased with an increase in reinforcing phase (Mg 2 Si) concentration. The fracture mode for the Mg 2 Si particles includes matrix yielding, decohesion, particle fracture. The deformation plasticity (Ramberg-Osgood) model was considered to investigate the micromechanical response under tension. Actual microstructure two-dimensional (2D) representative volume element (RVE) models have been developed to investigate the deformation and failure phenomenon of the composites. The FE analysis results have a great concurrence with the experimental one. It established that the composite's strength and failure initiation regions increased and the elongation decreased with an increase in Mg 2 Si concentration. It is noted that the eutectic Mg 2 Si morphology is the cause for failure initiation and then primary Mg 2 Si drive the final failure of the Al–Mg 2 Si composites. [ABSTRACT FROM AUTHOR]

In the present study, both experimental and numerical examinations were performed to understand the hypereutectic Al–Mg 2 Si composite's microstructural morphology, mechanical properties and fracture correlation. The innovation of this research includes the micromechanics studies and failure initiation in hypereutectic Al–Mg 2 Si composite through the compiled induce stress, deformation plasticity and energy dissipation theory subjected to tension. Ultimate tensile strength (UTS), toughness and elongation have decreased, but the yield strength has increased up to 25% Mg 2 Si addition and then decreased at the composites with 30 wt% Mg 2 Si because the brittle fracture increases due to the presence of comparatively coarser and dendritic primary Mg 2 Si particles. Additionally, an increase in the microporosity with the increase in Mg 2 Si concentration also affects the same. Finite element analysis (FEA) was performed using the Ramberg-Osgood constitutive model and actual microstructure 2D representative volume elements model. The FEA and experimental results have a satisfactory agreement. The fractography unveils the presence of a mix-mode of fracture, i.e. the ductile and the brittle fracture of the composites. Mises and Tresca failure criteria reveal that the distribution of stress is non-homogeneous and stress is localized in the narrow eutectic and irregular Mg 2 Si phase region, which acts as a crack initiation site. Analysis of the stress triaxiality and equivalent plastic strain distribution shows that void initiation and growth take place during the deformation of the Al–Mg 2 Si composites. The plastic dissipated energy distribution in deformed RVEs interestingly consents to the von mises stress, plastic strain and stress triaxiality analysis findings. [Display omitted] • The influence of Mg 2 Si wt. % was investigated both experimentally and numerically. • The most desirable mechanical properties were achieved in the Al–15Mg 2 Si composite. • Eutectic Mg 2 Si leads to the failure initiation of the composite. • Primary Mg 2 Si drives the final failure of the composite. • Energy dissipation is low in composite near the pseudo-eutectic region. [ABSTRACT FROM AUTHOR]