Multiscale Modelling Study Of The Mechanical Behaviours Based On Its Realistic Microstructure Of SiC_p/AZ91D Composites

Particle reinforced metal matrix composites (PRMMCs) offer high specific strength andspecific stiffness, good wear-resisting properties and good impact resistance over a widerange of operating conditions. This has led to their successful application in the fields ofaeronautic and astronautic, automotive, weapon, ammunition and electrical engineering etc.Research showed that, the mechanical properties of PRMMCs that are influenced by variousfactors, such as the preparation technology, the kinds of composite composition, the bondbetween matrix and particle, the heat treatment, and the particles’ shape, average diameter,volume fraction, orientation etc. that producing big difference of the composites.This article takes the mechanical behaviours of SiCp/AZ91D composite as the researchobject, the finite element simulation as the research means, contrast how the factors—like theshape, distribution, volume fraction and orientation etc. of the particles—affect thequasi-static behaviour and microstructure change of the composite.By using the scanning electron microscope (SEM)，obtain the two-dimensional microstructure chart of the SiCp/AZ91D composite with the volume fraction of10%and theaverage particle size of10μm, and then building the finite element model (original model)which have the realistic micromechanics architecture of the SiCp/AZ91D composite. Based onthe proper material models, mesh size, boundary and loading conditions, the simulation ofquasi-static tensile experiment could be realize at the end.Research showed that, the angular particles produce a stronger confining ability in themagnesium alloy matrix, the simplified model with the quadrangular particles display thestrongest enhancement effect, and the results are closer to the results of the original model.The cluster phenomenon of particles can also produce a stronger confining ability in some local area of the composite, but the uneven distribution of stress and strain are not conduciveto the overall properties of the composite. Higher volume fractions of particles may produce ahigher mechanical behaviour in the composite, however, with the particles are carried moreand more stress, these particles showed the more stress concentration phenomenon, that maylead the brittle fracture and failure of particles easily. Moreover, when the orientation ofparticles are parallel or vertical to loading direction, the particles could not be turned smoothly,made the strong confining ability in the magnesium alloy matrix, and the good enhancementeffect, but the serious damage of the particle in the composite. Thus summed up, theorientation of particles are changed due to the application of load, that is help to reduce thestress concentration phenomenon in the particles, because of the low plasticity and lowductility properties of AZ91D, the changes of particles’ orientation in the composite is notobvious, lead the particles’ shape and orientation smaller influence on the mechanicalbehaviours of the SiCp/AZ91D composite.